Tag Archives: China

Europe’s search for raw materials and hopes for nanotechnology-enabled solutions

A Feb. 27, 2015 news item on Nanowerk highlights the concerns over the availability of raw materials and European efforts to address those concerns,

Critical raw materials’ are crucial to many European industries but they are vulnerable to scarcity and supply disruption. As such, it is vital that Europe develops strategies for meeting the demand for raw materials. One such strategy is finding methods or substances that can replace the raw materials that we currently use. With this in mind, four EU projects working on substitution in catalysis, electronics and photonics presented their work at the Third Innovation Network Workshop on substitution of Critical Raw Materials hosted by the CRM_INNONET project in Brussels earlier this month [February 2015].

A Feb. 26, 2015 CORDIS press release, which originated the news item, goes on to describe four European Union projects working on nanotechnology-enabled solutions,

NOVACAM

NOVACAM, a coordinated Japan-EU project, aims to develop catalysts using non-critical elements designed to unlock the potential of biomass into a viable energy and chemical feedstock source.

The project is using a ‘catalyst by design’ approach for the development of next generation catalysts (nanoscale inorganic catalysts), as NOVACAM project coordinator Prof. Emiel Hensen from Eindhoven University of Technology in the Netherlands explained. Launched in September 2013, the project is developing catalysts which incorporate non-critical metals to catalyse the conversion of lignocellulose into industrial chemical feedstocks and bio-fuels. The first part of the project has been to develop the principle chemistry while the second part is to demonstrate proof of process. Prof. Hensen predicts that perhaps only two of three concepts will survive to this phase.

The project has already made significant progress in glucose and ethanol conversion, according to Prof. Hensen, and has produced some important scientific publications. The consortium is working with and industrial advisory board comprising Shell in the EU and Nippon Shokubai in Japan.

FREECATS

The FREECATS project, presented by project coordinator Prof. Magnus Rønning from the Norwegian University of Science and Technology, has been working over the past three years to develop new metal-free catalysts. These would be either in the form of bulk nanomaterials or in hierarchically organised structures – both of which would be capable of replacing traditional noble metal-based catalysts in catalytic transformations of strategic importance.

Prof. Magnus Rønning explained that the application of the new materials could eliminate the need for the use for platinum group metals (PGM) and rare earth metals – in both cases Europe is very reliant on other countries for these materials. Over the course of its research, FREECATS targeted three areas in particular – fuel cells, the production of light olefins and water and wastewater purification.

By working to replace the platinum in fuel cells, the project is supporting the EU’s aim of replacing the internal combustion engine by 2050. However, as Prof. Rønning noted, while platinum has been optimized for use over several decades, the materials FREECATS are using are new and thus come with their new challenges which the project is addressing.

HARFIR

Prof. Atsufumi Hirohata of the University of York in the United Kingdom, project coordinator of HARFIR, described how the project aims to discover an antiferromagnetic alloy that does not contain the rare metal Iridium. Iridium is becoming more and more widely used in numerous spin electronic storage devices, including read heads in hard disk drives. The world supply depends on Platinum ore that comes mainly from South Africa. The situation is much worse than for other rare earth elements as the price has been shooting up over recent years, according to Prof. Hirohata.

The HARFIR team, divided between Europe and Japan, aims to replace Iridium alloys with Heusler alloys. The EU team, led by Prof. Hirohata, has been working on the preparation of polycrystalline and epitaxial thin films of Heusler Alloys, with the material design led by theoretical calculations. The Japanese team, led by Prof. Koki Takanashi at Tohoku University, is meanwhile working on the preparation of epitaxial thin films, measurements of fundamental properties and structural/magnetic characterisation by neutron and synchrotron x-ray beams.

One of the biggest challenges has been that Heusler alloys have a relatively complicated atomic structure. In terms of HARFIR’s work, if any atomic disordering at the edge of nanopillar devices, the magnetic properties that are needed are lost. The team is exploring solutions to this challenge.

IRENA

Prof. of Esko Kauppinen Aalto University in Finland closed off the first session of the morning with his presentation of the IRENA project. Launched in September 2013, the project will run until mid 2017 working towards the aim of developing high performance materials, specifically metallic and semiconducting single-walled carbon nanotube (SWCNT) thin films to completely eliminate the use of the critical metals in electron devices. The ultimate aim is to replace Indium in transparent conducting films, and Indium and Gallium as a semiconductor in thin film field effect transistors (TFTs).

The IRENA team is developing an alternative that is flexible, transparent and stretchable so that it can meet the demands of the electronics of the future – including the possibility to print electronics.

IRENA involves three partners from Europe and three from Japan. The team has expertise in nanotube synthesis, thin film manufacturing and flexible device manufacturing, modelling of nanotube growth and thin film charge transport processes, and the project has benefitted from exchanges of team members between institutions. One of the key achievements so far is that the project has succeeded in using a nanotube thin film for the first time as the both the electrode and hole blocking layer in an organic solar cell.

You’ll note that Japan is a partner in all of these projects. In all probability, these initiatives have something to do with rare earths which are used in much of today’s electronics technology and Japan is sorely lacking in those materials. China, by comparison, has dominated the rare earths export industry and here’s an excerpt from my Nov. 1, 2013 posting where I outline the situation (which I suspect hasn’t changed much since),

As for the short supply mentioned in the first line of the news item, the world’s largest exporter of rare earth elements at 90% of the market, China, recently announced a cap according to a Sept. 6, 2013 article by David Stanway for Reuters. The Chinese government appears to be curtailing exports as part of an ongoing, multi-year strategy. Here’s how Cientifica‘s (an emerging technologies consultancy, etc.) white paper (Simply No Substitute?) about critical materials published in 2012 (?), described the situation,

Despite their name, REE are not that rare in the Earth’s crust. What has happened in the past decade is that REE exports from China undercut prices elsewhere, leading to the closure of mines such as the Mountain Pass REE mine in California. Once China had acquired a dominant market position, prices began to rise. But this situation will likely ease. The US will probably begin REE production from the Mountain Pass mine later in 2012, and mines in other countries are expected to start operation soon as well.

Nevertheless, owing to their broad range of uses REE will continue to exert pressures on their supply – especially for countries without notable REE deposits. This highlights two aspects of importance for strategic materials: actual rarity and strategic supply issues such as these seen for REE. Although strategic and diplomatic supply issues may have easier solutions, their consideration for manufacturing industries will almost be the same – a shortage of crucial supply lines.

Furthermore, as the example of REE shows, the identification of long-term supply problems can often be difficult, and not every government has the same strategic foresight that the Chinese demonstrated. And as new technologies emerge, new elements may see an unexpected, sudden demand in supply. (pp. 16-17)

Meanwhile, in response to China’s decision to cap its 2013 REE exports, the Russian government announced a $1B investment to 2018 in rare earth production,, according to a Sept. 10, 2013 article by Polina Devitt for Reuters.

I’m not sure you’ll be able to access Tim Harper’s white paper as he is now an independent, serial entrepreneur. I most recently mentioned him in relation to his articles (on Azonano) about the nanotechnology scene in a Feb. 12, 2015 posting where you’ll also find contact details for him.

A 2nd European roadmap for graphene

About 2.5 years ago there was an article titled, “A roadmap for graphene” (behind a paywall) which Nature magazine published online in Oct. 2012. I see at least two of the 2012 authors, Konstantin (Kostya) Novoselov and Vladimir Fal’ko,, are party to this second, more comprehensive roadmap featured in a Feb. 24, 2015 news item on Nanowerk,

In October 2013, academia and industry came together to form the Graphene Flagship. Now with 142 partners in 23 countries, and a growing number of associate members, the Graphene Flagship was established following a call from the European Commission to address big science and technology challenges of the day through long-term, multidisciplinary R&D efforts.

A Feb.  24, 2015 University of Cambridge news release, which originated the news item, describes the roadmap in more detail,

In an open-access paper published in the Royal Society of Chemistry journal Nanoscale, more than 60 academics and industrialists lay out a science and technology roadmap for graphene, related two-dimensional crystals, other 2D materials, and hybrid systems based on a combination of different 2D crystals and other nanomaterials. The roadmap covers the next ten years and beyond, and its objective is to guide the research community and industry toward the development of products based on graphene and related materials.

The roadmap highlights three broad areas of activity. The first task is to identify new layered materials, assess their potential, and develop reliable, reproducible and safe means of producing them on an industrial scale. Identification of new device concepts enabled by 2D materials is also called for, along with the development of component technologies. The ultimate goal is to integrate components and structures based on 2D materials into systems capable of providing new functionalities and application areas.

Eleven science and technology themes are identified in the roadmap. These are: fundamental science, health and environment, production, electronic devices, spintronics, photonics and optoelectronics, sensors, flexible electronics, energy conversion and storage, composite materials, and biomedical devices. The roadmap addresses each of these areas in turn, with timelines.

Research areas outlined in the roadmap correspond broadly with current flagship work packages, with the addition of a work package devoted to the growing area of biomedical applications, to be included in the next phase of the flagship. A recent independent assessment has confirmed that the Graphene Flagship is firmly on course, with hundreds of research papers, numerous patents and marketable products to its name.

Roadmap timelines predict that, before the end of the ten-year period of the flagship, products will be close to market in the areas of flexible electronics, composites, and energy, as well as advanced prototypes of silicon-integrated photonic devices, sensors, high-speed electronics, and biomedical devices.

“This publication concludes a four-year effort to collect and coordinate state-of-the-art science and technology of graphene and related materials,” says Andrea Ferrari, director of the Cambridge Graphene Centre, and chairman of the Executive Board of the Graphene Flagship. “We hope that this open-access roadmap will serve as the starting point for academia and industry in their efforts to take layered materials and composites from laboratory to market.” Ferrari led the roadmap effort with Italian Institute of Technology physicist Francesco Bonaccorso, who is a Royal Society Newton Fellow of the University of Cambridge, and a Fellow of Hughes Hall.

“We are very proud of the joint effort of the many authors who have produced this roadmap,” says Jari Kinaret, director of the Graphene Flagship. “The roadmap forms a solid foundation for the graphene community in Europe to plan its activities for the coming years. It is not a static document, but will evolve to reflect progress in the field, and new applications identified and pursued by industry.”

I have skimmed through the report briefly (wish I had more time) and have a couple of comments. First, there’s an excellent glossary of terms for anyone who might stumble over chemical abbreviations and/or more technical terminology. Second, they present a very interesting analysis of the intellectual property (patents) landscape (Note: Links have been removed. Incidental numbers are footnote references),

In the graphene area, there has been a particularly rapid increase in patent activity from around 2007.45 Much of this is driven by patent applications made by major corporations and universities in South Korea and USA.53 Additionally, a high level of graphene patent activity in China is also observed.54 These features have led some commentators to conclude that graphene innovations arising in Europe are being mainly exploited elsewhere.55 Nonetheless, an analysis of the Intellectual Property (IP) provides evidence that Europe already has a significant foothold in the graphene patent landscape and significant opportunities to secure future value. As the underlying graphene technology space develops, and the GRM [graphene and related materials] patent landscape matures, re-distribution of the patent landscape seems inevitable and Europe is well positioned to benefit from patent-based commercialisation of GRM research.

Overall, the graphene patent landscape is growing rapidly and already resembles that of sub-segments of the semiconductor and biotechnology industries,56 which experience high levels of patent activity. The patent strategies of the businesses active in such sub-sectors frequently include ‘portfolio maximization’56 and ‘portfolio optimization’56 strategies, and the sub-sectors experience the development of what commentators term ‘patent thickets’56, or multiple overlapping granted patent rights.56 A range of policies, regulatory and business strategies have been developed to limit such patent practices.57 In such circumstances, accurate patent landscaping may provide critical information to policy-makers, investors and individual industry participants, underpinning the development of sound policies, business strategies and research commercialisation plans.

It sounds like a patent thicket is developing (Note: Links have been removed. Incidental numbers are footnote references),,

Fig. 13 provides evidence of a relative increase in graphene patent filings in South Korea from 2007 to 2009 compared to 2004–2006. This could indicate increased commercial interest in graphene technology from around 2007. The period 2010 to 2012 shows a marked relative increase in graphene patent filings in China. It should be noted that a general increase in Chinese patent filings across many ST domains in this period is observed.76 Notwithstanding this general increase in Chinese patent activity, there does appear to be increased commercial interest in graphene in China. It is notable that the European Patent Office contribution as a percentage of all graphene patent filings globally falls from a 8% in the period 2007 to 2009 to 4% in the period 2010 to 2012.

The importance of the US, China and South Korea is emphasised by the top assignees, shown in Fig. 14. The corporation with most graphene patent applications is the Korean multinational Samsung, with over three times as many filings as its nearest rival. It has also patented an unrivalled range of graphene-technology applications, including synthesis procedures,77 transparent display devices,78 composite materials,79 transistors,80 batteries and solar cells.81 Samsung’s patent applications indicate a sustained and heavy investment in graphene R&D, as well as collaboration (co-assignment of patents) with a wide range of academic institutions.82,83

 

image file: c4nr01600a-f14.tif
Fig. 14 Top 10 graphene patent assignees by number and cumulative over all time as of end-July 2014. Number of patents are indicated in the red histograms referred to the left Y axis, while the cumulative percentage is the blue line, referred to the right Y axis.

It is also interesting to note that patent filings by universities and research institutions make up a significant proportion ([similar]50%) of total patent filings: the other half comprises contributions from small and medium-sized enterprises (SMEs) and multinationals.

Europe’s position is shown in Fig. 10, 12 and 14. While Europe makes a good showing in the geographical distribution of publications, it lags behind in patent applications, with only 7% of patent filings as compared to 30% in the US, 25% in China, and 13% in South Korea (Fig. 13) and only 9% of filings by academic institutions assigned in Europe (Fig. 15).

 

image file: c4nr01600a-f15.tif
Fig. 15 Geographical breakdown of academic patent holders as of July 2014.

While Europe is trailing other regions in terms of number of patent filings, it nevertheless has a significant foothold in the patent landscape. Currently, the top European patent holder is Finland’s Nokia, primarily around incorporation of graphene into electrical devices, including resonators and electrodes.72,84,85

This may sound like Europe is trailing behind but that’s not the case according to the roadmap (Note: Links have been removed. Incidental numbers are footnote references),

European Universities also show promise in the graphene patent landscape. We also find evidence of corporate-academic collaborations in Europe, including e.g. co-assignments filed with European research institutions and Germany’s AMO GmbH,86 and chemical giant BASF.87,88 Finally, Europe sees significant patent filings from a number of international corporate and university players including Samsung,77 Vorbeck Materials,89 Princeton University,90–92 and Rice University,93–95 perhaps reflecting the quality of the European ST base around graphene, and its importance as a market for graphene technologies.

There are a number of features in the graphene patent landscape which may lead to a risk of patent thickets96 or ‘multiple overlapping granted patents’ existing around aspects of graphene technology systems. [emphasis mine] There is a relatively high volume of patent activity around graphene, which is an early stage technology space, with applications in patent intensive industry sectors. Often patents claim carbon nano structures other than graphene in graphene patent landscapes, illustrating difficulties around defining ‘graphene’ and mapping the graphene patent landscape. Additionally, the graphene patent nomenclature is not entirely settled. Different patent examiners might grant patents over the same components which the different experts and industry players call by different names.

For anyone new to this blog, I am not a big fan of current patent regimes as they seem to be stifling rather encouraging innovation. Sadly, patents and copyright were originally developed to encourage creativity and innovation by allowing the creators to profit from their ideas. Over time a system designed to encourage innovation has devolved into one that does the opposite. (My Oct. 31, 2011 post titled Patents as weapons and obstacles, details my take on this matter.) I’m not arguing against patents and copyright but suggesting that the system be fixed or replaced with something that delivers on the original intention.

Getting back to the matter at hand, here’s a link to and a citation for the 200 pp. 2015 European Graphene roadmap,

Science and technology roadmap for graphene, related two-dimensional crystals, and hybrid systems by Andrea C. Ferrari, Francesco Bonaccorso, Vladimir Fal’ko, Konstantin S. Novoselov, Stephan Roche, Peter Bøggild, Stefano Borini, Frank H. L. Koppens, Vincenzo Palermo, Nicola Pugno, José A. Garrido, Roman Sordan, Alberto Bianco, Laura Ballerini, Maurizio Prato, Elefterios Lidorikis, Jani Kivioja, Claudio Marinelli, Tapani Ryhänen, Alberto Morpurgo, Jonathan N. Coleman, Valeria Nicolosi, Luigi Colombo, Albert Fert, Mar Garcia-Hernandez, Adrian Bachtold, Grégory F. Schneider, Francisco Guinea, Cees Dekker, Matteo Barbone, Zhipei Sun, Costas Galiotis,  Alexander N. Grigorenko, Gerasimos Konstantatos, Andras Kis, Mikhail Katsnelson, Lieven Vandersypen, Annick Loiseau, Vittorio Morandi, Daniel Neumaier, Emanuele Treossi, Vittorio Pellegrini, Marco Polini, Alessandro Tredicucci, Gareth M. Williams, Byung Hee Hong, Jong-Hyun Ahn, Jong Min Kim, Herbert Zirath, Bart J. van Wees, Herre van der Zant, Luigi Occhipinti, Andrea Di Matteo, Ian A. Kinloch, Thomas Seyller, Etienne Quesnel, Xinliang Feng,  Ken Teo, Nalin Rupesinghe, Pertti Hakonen, Simon R. T. Neil, Quentin Tannock, Tomas Löfwander and Jari Kinaret. Nanoscale, 2015, Advance Article DOI: 10.1039/C4NR01600A First published online 22 Sep 2014

Here’s a diagram illustrating the roadmap process,

Fig. 122 The STRs [science and technology roadmaps] follow a hierarchical structure where the strategic level in a) is connected to the more detailed roadmap shown in b). These general roadmaps are the condensed form of the topical roadmaps presented in the previous sections, and give technological targets for key applications to become commercially competitive and the forecasts for when the targets are predicted to be met.  Courtesy: Researchers and  the Royal Society's journal, Nanoscale

Fig. 122 The STRs [science and technology roadmaps] follow a hierarchical structure where the strategic level in a) is connected to the more detailed roadmap shown in b). These general roadmaps are the condensed form of the topical roadmaps presented in the previous sections, and give technological targets for key applications to become commercially competitive and the forecasts for when the targets are predicted to be met.
Courtesy: Researchers and the Royal Society’s journal, Nanoscale

The image here is not the best quality; the one embedded in the relevant Nanowerk news item is better.

As for the earlier roadmap, here’s my Oct. 11, 2012 post on the topic.

Rice University collaborates with Shandong University on a Joint Center for Carbon Nanomaterials

They’re not billing this as a joint US-China project but with Rice University being in Texas, US and Shandong University being in Shandong (province) in China, I think it’s reasonable to describe it that way. Here’s more about the project from a Feb. 4, 2015 news item on Azonano,

Scientists from Rice University and Shandong University, China, celebrated the opening of the Joint Center for Carbon Nanomaterials, a collaborative facility to study nanotechnology, on Feb. 1 [2015].

Rice faculty members Pulickel Ajayan and Jun Lou, the chair and associate chair, respectively, of the university’s Department of Materials Science and NanoEngineering, took part in the ceremony along with Rice alumnus Lijie Ci, director of the new center and a professor of materials science and engineering at Shandong. The center’s dedication was part of the first International Workshop on Engineering and Applications of Nanocarbon, held Jan. 31-Feb. 2 [2015].

Determining where this new center is located proved to be a challenge. From a Feb. 2, 2015 Rice University news release, which originated the news item,

“We at Rice University are excited and honored to collaborate with Shandong University on this important endeavor,” Rice President David Leebron said in a message recorded for the ceremony. [emphasis mine] “The center represents and combines two very important initiatives for Rice: research excellence and applications in nanosciences and long-term partnerships with the best institutions worldwide.”

“A lot of people are working on carbon nanoscience on both campuses, and we expect they will be interested in taking part,” Ajayan said. “Nanotubes and graphene are essentially the building blocks for the center, but Lijie wants to build ecologically relevant, applied research that can be commercialized. That’s the long-term goal. All of the experience we have had in the area will be beneficial.”

Ajayan expects students from both universities will travel. “People from Rice will be engaged in some of the activities of this joint center, including advising students there. And we hope Shandong students will have the opportunity to come to Rice for a short time,” he said. “The center also contributes to Rice’s goal to build closer connections with China.” [emphases mine]

Ajayan and Ci came to Rice together in 2007 from Rensselaer Polytechnic Institute; Ajayan was a faculty member and Ci was a postdoctoral researcher. At Rice, they introduced the darkest material ever measured at the time of its invention in 2008, an accomplishment that landed them in the Guinness Book of World Records.

They also collaborated on the first two-dimensional material to incorporate graphene and hexagonal boron nitride in a seamless lattice. Such 2-D materials have since become the focus of worldwide research for their potential as electronic components. And Ci, Lou and Ajayan worked together to study the nanoscale friction properties of carbon nanotubes.

I’m inferring from the portions I’ve highlighted that this center is located at Shandong University.

Graphene with a pentagonal pattern

Graphene has been viewed, until now, as having an hexgonal (six-sided) pattern. However, researchers have discovered a new graphene pattern according to a Feb. 3, 2015 news item on Nanowerk,

Researchers at Virginia Commonwealth University and universities in China and Japan have discovered a new structural variant of carbon called “penta-graphene” – a very thin sheet of pure carbon that has a unique structure inspired by a pentagonal pattern of tiles found paving the streets of Cairo.

The newly discovered material, called penta-graphene, is a single layer of carbon pentagons that resembles the Cairo tiling, and that appears to be dynamically, thermally and mechanically stable.

A Feb. 3, 2015 Virginia Commonwealth University (VCU) news release by Brian McNeill (also on EurekAlert), which originated the news item, provides more information about the research,

“The three last important forms of carbon that have been discovered were fullerene, the nanotube and graphene. Each one of them has unique structure. Penta-graphene will belong in that category,” said the paper’s senior author, Puru Jena, Ph.D., distinguished professor in the Department of Physics in VCU’s College of Humanities and Sciences.

Qian Wang, Ph.D., a professor at Peking University and an adjunct professor at VCU, was dining in a restaurant in Beijing with her husband when she noticed artwork on the wall depicting pentagon tiles from the streets of Cairo.

“I told my husband, “Come, see! This is a pattern composed only of pentagons,'” she said. “I took a picture and sent it to one of my students, and said, ‘I think we can make this. It might be stable. But you must check it carefully.’ He did, and it turned out that this structure is so beautiful yet also very simple.”

Most forms of carbon are made of hexagonal building blocks, sometimes interspersed with pentagons. Penta-graphene would be a unique two-dimensional carbon allotrope composed exclusively of pentagons.

Along with Jena and Wang, the paper’s authors include Shunhong Zhang, Ph.D candidate, from Peking University; Jian Zhou, Ph.D., a postdoctoral researcher at VCU; Xiaoshuang Chen, Ph.D., from the Chinese Academy of Science in Shanghai; and Yoshiyuki Kawazoe, Ph.D., from Tohoku University in Sendai, Japan.

The researchers simulated the synthesis of penta-graphene using computer modelling. The results suggest that the material might outperform graphene in certain applications, as it would be mechanically stable, possess very high strength, and be capable of withstanding temperatures of up to 1,000 degrees Kelvin.

“You know the saying, diamonds are forever? That’s because it takes a lot of energy to convert diamond back into graphite,” Jena said. “This will be similar.”

Penta-graphene has several interesting and unusual properties, Jena said. For example, penta-graphene is a semiconductor, whereas graphene is a conductor of electricity.

“When you take graphene and roll it up, you make what is called a carbon nanotube which can be metallic or semiconducting,” Jena said. “Penta-graphene, when you roll it up, will also make a nanotube, but it is always semiconducting.”

The way the material stretches is also highly unusual, the researchers said.

“If you stretch graphene, it will expand along the direction it is stretched, but contract along the perpendicular direction.” Wang said. “However, if you stretch penta-graphene, it will expand in both directions.”

The material’s mechanical strength, derived from a rare property known as Negative Poisson’s Ratio, may hold especially interesting applications for technology, the researchers said.

Penta-graphene’s properties suggest that it may have applications in electronics, biomedicine, nanotechnology and more.

The next step, Jena said, is for scientists to synthesize penta-graphene.

“Once you make it, it [will be] very stable. So the question becomes, how do you make it? In this paper, we have some ideas. Right now, the project is theoretical. It’s based on computer modelling, but we believe in this prediction quite strongly. And once you make it, it will open up an entirely new branch of carbon science. Two-dimensional carbon made completely of pentagons has never been known.”

Here’s a graphic representation of the new graphene material,

Caption: The newly discovered material, called penta-graphene, is a single layer of carbon pentagons that resembles the Cairo tiling, and that appears to be dynamically, thermally and mechanically stable. Credit: Virginia Commonwealth University

Caption: The newly discovered material, called penta-graphene, is a single layer of carbon pentagons that resembles the Cairo tiling, and that appears to be dynamically, thermally and mechanically stable.
Credit: Virginia Commonwealth University

Here’s a link to and a citation for the paper,

Penta-graphene: A new carbon allotrope by Shunhong Zhanga, Jian Zhou, Qian Wanga, Xiaoshuang Chen, Yoshiyuki Kawazoe, and Puru Jena. PNAS February 2, 2015 doi: 10.1073/pnas.1416591112 Published online before print February 2, 2015

This paper is behind a paywall.

Canadian nanoscientist, Federico Rosei, picks up a new honour (this one is from China)

I covered two of Federico Rosei’s awards last year in a Jan. 27, 2014 post about his Canadian Society for Chemistry award and in a Feb. 4, 2014 post about his E.W.R. Steacie Memorial Fellowship from Canada’s Natural Sciences and Engineering Research Council. This year, China has honoured the Dr. Rosei with a scholar’s award that requires regular visits to China. From a Jan. 28, 2015 news item on Azonano,

Professor Federico Rosei of the INRS Énergie Matériaux Télécommunications Research Centre has won the Chang Jiang Scholars Award, a highly prestigious distinction for world-class researchers given by the Chinese government. Professor Rosei was honoured for his work in the field of organic and inorganic nanomaterials. This is the first time the award has been given to an INRS faculty member. [INRS is Québec’s Institut national de la recherche scientifique; the Université de Québec’s research branch]

A Jan. 23, 2015 INRS news release by Gisèle Bolduc, which originated the news item, fills in some more details about the award and Dr. Rosei,

As a Chang Jiang scholar, Professor Rosei will make regular visits to the University of Electronic Science and Technology of China (UESTC) over the next three years, where he will help set up an R&D platform in nanomaterials and electronic and optoelectronic devices. In addition to these joint research projects, Professor Rosei will train young Chinese researchers, make scientific presentations, and forge international academic ties.

Federico Rosei’s tenure as a Chang Jiang scholar will complement and enhance his work as UNESCO Chair on Materials and Technologies for Energy Conversion, Saving and Storage (MATECSS). This INRS research chair is part of a North-South/South-South initiative to promote the international sharing of technical and scientific knowledge in the areas of renewable energies and sustainable development.

“Dr. Federico Rosei is an outstanding professor and researcher, and a true world leader in his field,” noted Yves Bégin, vice president (or principal) of research and academic affairs. “INRS is extremely proud to have Professor Rosei among its professors. Beyond his major scientific advances in his field, his presence in our institution helps build invaluable bridges between the local team of professors and large-scale international research projects.”

About the Chang Jiang Scholars Awards

Founded in 1998 by the Chinese Ministry of Education, the Chang Jiang Scholars program annually brings some 50 eminent international scholars, mainly in science and technology, to Chinese universities. The program’s aim is to raise standards of research in Chinese universities through collaboration with leading scientists from the world over.

About Federico Rosei

Professor Federico Rosei’s work in material physics has led to scientific innovations and practical applications in electronics, energy, and the life sciences. He is a Fellow of the Royal Society of Canada, distinguished lecturer at IEEE Nanotechnology Council (NTC), UNESCO Chair on Materials and Technologies for Energy Conversion, Saving and Storage (MATECSS), and recipient of the NSERC 2014 E.W.R. Steacie Memorial Fellowship from NSERC. Professor Rosei has won numerous awards including the 2014 José Vasconcelos World Award of Education from the World Cultural Council, the 2011 Friedrich Wilhelm Bessel award from the Alexander von Humboldt Foundation, the 2013 Herzberg Medal from the Canadian Association of Physicists, and the 2011 Rutherford Memorial Medal in Chemistry from the Royal Society of Canada. Dr. Rosei is a member of the European Academy of Sciences, a senior member of the Institute of Electrical and Electronics Engineers (IEEE) and the Society for Photo-Image Engineers (SPIE), and a Fellow of the American Physical Society; the U.S. Association for the Advancement of Science; the Engineering Institute of Canada; the Institute of Physics; the Royal Society of Chemistry; the Institute of Materials, Minerals and Mining; the Institute of Engineering and Technology; the Institute of Nanotechnology; and the Australian Institute of Physics.

Odd, there’s no mention of the Canadian Society for Chemistry award but since this man seems to be the recipient of many awards, I imagine some hard choices had to be made when writing him up.

For anyone who’d prefer to read about Rosei in French or would like to test their French reading skills, here’s Gisèle Bolduc’s 21 janvier 2015 actualité.

The perfect keyboard: it self-cleans and self-powers and it can identify its owner(s)

There’s a pretty nifty piece of technology being described in a Jan. 21, 2015 news item on Nanowerk, which focuses on the security aspects first (Note: A link has been removed),

In a novel twist in cybersecurity, scientists have developed a self-cleaning, self-powered smart keyboard that can identify computer users by the way they type. The device, reported in the journal ACS Nano (“Personalized Keystroke Dynamics for Self-Powered Human–Machine Interfacing”), could help prevent unauthorized users from gaining direct access to computers.

A Jan. 21, 2015 American Chemical Society (ACS) news release (also on EurekAlert), which originated the news item, continues with the keyboard’s security features before briefly mentioning the keyboard’s self-powering and self-cleaning capabilities,

Zhong Lin Wang and colleagues note that password protection is one of the most common ways we control who can log onto our computers — and see the private information we entrust to them. But as many recent high-profile stories about hacking and fraud have demonstrated, passwords are themselves vulnerable to theft. So Wang’s team set out to find a more secure but still cost-effective and user-friendly approach to safeguarding what’s on our computers.

The researchers developed a smart keyboard that can sense typing patterns — including the pressure applied to keys and speed — that can accurately distinguish one individual user from another. So even if someone knows your password, he or she cannot access your computer because that person types in a different way than you would. It also can harness the energy generated from typing to either power itself or another small device. And the special surface coating repels dirt and grime. The scientists conclude that the keyboard could provide an additional layer of protection to boost the security of our computer systems.

Here’s a link to and a citation for the paper,

Personalized Keystroke Dynamics for Self-Powered Human–Machine Interfacing by Jun Chen, Guang Zhu, Jin Yang, Qingshen Jing, Peng Bai, Weiqing Yang, Xuewei Qi, Yuanjie Su, and Zhong Lin Wang. ACS Nano, Article ASAP DOI: 10.1021/nn506832w Publication Date (Web): December 30, 2014

Copyright © 2014 American Chemical Society

This paper is behind a paywall. I did manage a peek at the paper and found that the keyboard is able to somehow harvest the mechanical energy of typing and turn it into electricity so it can self-power. Self-cleaning is made possible by a nanostructure surface modification. An idle thought and a final comment. First, I wonder what happens if you want to or have to share your keyboard? Second, a Jan. 21, 2015 article about the intelligent keyboard by Luke Dormehl for Fast Company notes that the researchers are from the US and China and names two of the institutions involved in this collaboration, Georgia Institute of Technology and the Beijing Institute of Nanoenergy and Nanosystems,.

ETA Jan. 23, 2015: There’s a Georgia Institute of Technology Jan. 21, 2015 news release on EurekAlert about the intelligent keyboard which offers more technical details such as these,

Conventional keyboards record when a keystroke makes a mechanical contact, indicating the press of a specific key. The intelligent keyboard records each letter touched, but also captures information about the amount of force applied to the key and the length of time between one keystroke and the next. Such typing style is unique to individuals, and so could provide a new biometric for securing computers from unauthorized use.

In addition to providing a small electrical current for registering the key presses, the new keyboard could also generate enough electricity to charge a small portable electronic device or power a transmitter to make the keyboard wireless.

An effect known as contact electrification generates current when the user’s fingertips touch a plastic material on which a layer of electrode material has been coated. Voltage is generated through the triboelectric and electrostatic induction effects. Using the triboelectric effect, a small charge can be produced whenever materials are brought into contact and then moved apart.

“Our skin is dielectric and we have electrostatic charges in our fingers,” Wang noted. “Anything we touch can become charged.”

Instead of individual mechanical keys as in traditional keyboards, Wang’s intelligent keyboard is made up of vertically-stacked transparent film materials. Researchers begin with a layer of polyethylene terephthalate between two layers of indium tin oxide (ITO) that form top and bottom electrodes.

Next, a layer of fluorinated ethylene propylene (FEP) is applied onto the ITO surface to serve as an electrification layer that generates triboelectric charges when touched by fingertips. FEP nanowire arrays are formed on the exposed FEP surface through reactive ion etching.

The keyboard’s operation is based on coupling between contact electrification and electrostatic induction, rather than the traditional mechanical switching. When a finger contacts the FEP, charge is transferred at the contact interface, injecting electrons from the skin into the material and creating a positive charge.

When the finger moves away, the negative charges on the FEP side induces positive charges on the top electrode, and equal amounts of negative charges on the bottom electrode. Consecutive keystrokes produce a periodic electrical field that drives reciprocating flows of electrons between the electrodes. Though eventually dissipating, the charges remain on the FEP surface for an extended period of time.

Wang believes the new smart keyboard will be competitive with existing keyboards, in both cost and durability. The new device is based on inexpensive materials that are widely used in the electronics industry.

Microplasm-generated gold nanoparticles and the heart

Scientists are hoping they’ve found a better way to detect early signs of a heart attack according to a Jan. 15, 2015 news item on Nanotechnology Now,

NYU [New York University] Polytechnic School of Engineering professors have been collaborating with researchers from Peking University on a new test strip that is demonstrating great potential for the early detection of certain heart attacks.

Kurt H. Becker, a professor in the Department of Applied Physics and the Department of Mechanical and Aerospace Engineering, and WeiDong Zhu, a research associate professor in the Department of Mechanical and Aerospace Engineering, are helping develop a new colloidal gold test strip for cardiac troponin I (cTn-I) detection. The new strip uses microplasma-generated gold nanoparticles (AuNPs) and shows much higher detection sensitivity than conventional test strips. The new cTn-I test is based on the specific immune-chemical reactions between antigen and antibody on immunochromatographic test strips using AuNPs.

A Jan. 14, 2015 NYU Polytechnic School of Engineering news release (also on EurekAlert but dated Jan. 15, 2015), which originated the news item, explains what makes these new test strips more sensitive (hint: microplasma-generated gold nanoparticles),

Compared to AuNPs produced by traditional chemical methods, the surfaces of the gold nanoparticles generated by the microplasma-induced liquid chemical process attract more antibodies, which results in significantly higher detection sensitivity.

cTn-I is a specific marker for myocardial infarction. The cTn-I level in patients experiencing cardiac infarction is several thousand times higher than in healthy people. The early detection of cTn-I is therefore a key factor of heart attack diagnosis and therapy.

The use of microplasmas to generate AuNP is yet another application of the microplasma technology developed by Becker and Zhu.  Microplasmas have been used successfully in dental applications (improved bonding, tooth whitening, root canal disinfection), biological decontamination (inactivation of microorganisms and biofilms), and disinfection and preservation of fresh fruits and vegetables.

The microplasma-assisted synthesis of AuNPs has great potential for other biomedical and therapeutic applications such as tumor detection, cancer imaging, drug delivery, and treatment of degenerative diseases such as Alzheimer’s.

The routine use of gold nanoparticles in therapy and disease detection in patients is still years away: longer for therapeutic applications and shorter for biosensors. The biggest hurdle to overcome is the fact that the synthesis of monodisperse, size-controlled gold nanoparticles, even using microplasmas, is still a costly, time-consuming, and labor-intensive process, which limits their use currently to small-scale clinical studies, Becker explained.

Here’s a link to and citation for the paper,

Microplasma-Assisted Synthesis of Colloidal Gold Nanoparticles and Their Use in the Detection of Cardiac Troponin I (cTn-I) by Ruixue Wang, Shasha Zuo, Dong Wu, Jue Zhang, Weidong Zhu, Kurt H. Becker, and Jing Fang. Plasma Processes and Polymers DOI: 10.1002/ppap.201400127 Article first published online: 11 DEC 2014

© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

This article is behind a paywall.

For anyone curious about the more common chemical methods of producing gold nanoparticles, there’s this video produced in Australia by TechNyou Education. There’s a specific technique described which I believe is one of the most commonly used and I think this can be generalized to other gold nanoparticle chemical production processes,

One more thing, this video runs over my 5 min. policy limit for videos. To do this, I battled my inclination to include something that I think is useful for understanding more about nanoparticles and my desire to make sure that my blog doesn’t get too bloated.

Of airborne nanomaterials, bacterial microbiomes, viral microbiomes, and paper sensors

There’s a Jan. 14, 2015 news item on Nanowerk from the Virginia Polytechnic Institute (Virginia Tech) which is largely a personal profile featuring some basic information (useful for those new to the topic) about airborne nanoparticles (Note: A link has been removed),

The Harvard educated undergraduate [Linsey Marr,  professor of civil and environmental engineering, Virginia Tech] who obtained her Ph.D. from University of California at Berkeley and trained as a postdoctoral researcher with a Nobel laureate of chemistry at MIT is now among a handful of researchers in the world who are addressing concerns about engineered nanomaterials in the atmosphere.

Marr is part of the National Science Foundation’s Center for the Environmental Implications of Nanotechnology and her research group has characterized airborne nanoparticles at every point of their life cycle. This cycle includes production at a commercial manufacturing facility, use by consumers in the home, and disposal via incineration.

A Jan. 14, 2015 Virginia Tech news release, which originated the news item, quotes Marr on the current thinking about airborne nanoparticles,

“Results have shown that engineered nanomaterials released into the air are often aggregated with other particulate matter, such as combustion soot or ingredients in consumer spray products, and that the size of such aggregates may range from smaller than 10 nanometers to larger than 10 microns,” Marr revealed. She was referring to studies completed by research group members Marina Quadros Vance of Florianopolis, Brazil, a research scientist with the Virginia Tech Institute of Critical Technology and Applied Science, and Eric Vejerano, of Ligao, Philippines, a post-doctoral associate in civil and environmental engineering.

Size matters if these aggregates are inhaled.

Another concern is the reaction of a nanomaterial such as a fullerene with ozone at environmentally relevant concentration levels. Marr’s graduate student, Andrea Tiwari, of Mankato, Minnesota, said the resulting changes in fullerene could lead to enhanced toxicity.

The story then segues into airborne pathogens and viruses eventually honing in on virus microbiomes and bacterial microbiomes (from the news release),

Marr is a former Ironman triathlete who obviously has strong interests in what she is breathing into her own body. So it would be natural for her to expand her study of engineered nanoparticles traveling in the atmosphere to focus on airborne pathogens.

She did so by starting to consider the influenza virus as an airborne pollutant. She applied the same concepts and tools used for studying environmental contaminants and ambient aerosols to the examination of the virus.

She looked at viruses as “essentially self-assembled nanoparticles that are capable of self-replication.”

Her research team became the first to measure influenza virus concentrations in ambient air in a children’s day care center and on airplanes. When they conducted their studies, the Virginia Tech researchers collected samples from a waiting room of a health care center, two toddlers’ rooms and one babies’ area of a childcare center, as well as three cross-country flights between Roanoke, Virginia., and San Francisco. They collected 16 samples between Dec. 10, 2009 and Apr. 22, 2010.

“Half of the samples were confirmed to contain aerosolized influenza A viruses,” Marr said. The childcare samples were the most infected at 75 percent. Next, airplane samples reached 67 percent contamination, and health center numbers came in at 33 percent.

This study serves as a foundation for new work started about a year ago in her lab.

Marr collaborated with Aaron J. Prussin II, of Blacksburg, Virginia, and they successfully secured for him a postdoctoral fellowship from the Alfred P. Sloan Foundation to characterize the bacterial and viral microbiome — the ecological community of microorganisms — of the air in a daycare center.

They are now attempting to determine seasonal changes of both the viral microbiome and the bacterial microbiome in a daycare setting, and examine how changes in the microbiome are related to naturally occurring changes in the indoor environment.

“Little is known about the viral component of the microbiome and it is important because viruses are approximately 10 times more abundant than bacteria, and they help shape the bacterial community. Research suggests that viruses do have both beneficial and harmful interactions with bacteria,” Prussin said.

With Prussin and Marr working together they hope to verify their hypothesis that daycare centers harbor unique, dynamic microbiomes with plentiful bacteria and viruses. They are also looking at what seasonal changes might bring to a daycare setting.

They pointed to the effect of seasonal changes because in previous work, Marr, her former graduate student Wan Yang, of Shantou, China, and Elankumaran Subbiah, a virologist in the biomedical sciences and pathobiology department of the Virginia-Maryland College of Veterinary Medicine, measured the influenza A virus survival rate at various levels of humidity.

Their 2012 study presented for the first time the relationship between the influenza A virus viability in human mucus and humidity over a large range of relative humidities, from 17 percent to 100 percent. They found the viability of the virus was highest when the relative humidity was either close to 100 percent or below 50 percent. The results in human mucus may help explain influenza’s seasonality in different regions.

According to the news release Marr and her colleagues have developed a fast and cheap technology for detection of airborne pathogens (Note: A link has been removed),

With the urgent need to understand the dynamics of airborne pathogens, especially as one considers the threats of bioterrorism, pandemic influenza, and other emerging infectious diseases, Marr said “a breakthrough technology is required to enable rapid, low-cost detection of pathogens in air.”

Along with Subbiah and Peter Vikesland,  professor of civil and environmental engineering, they want to develop readily deployable, inexpensive, paper-based sensors for airborne pathogen detection.

In 2013 they received funding of almost $250,000 from Virginia Tech’s Institute for Critical Technology and Applied Science, a supporter of the clustering of research groups, to support their idea of creating paper-based sensors based on their various successes to date.

Marr explained the sensors “would use a sandwich approach. The bottom layer is paper containing specialized DNA that will immobilize the virus. The middle layer is the virus, which sticks to the specialized DNA on the bottom layer. The top layer is additional specialized DNA that sticks to the virus. This DNA is attached to gold nanoparticles that are easily detectable using a technique known as Raman microscopy.”

They key to their approach is that it combines high-tech with low-tech in the hopes of keeping the assay costs low. Their sampling method will use a bicycle pump, and low cost paper substrates. They hope that they will be able to incorporate smart-phone based signal transduction for the detection. Using this approach, they believe “even remote corners of the world” would be able to use the technique.

Vikesland previously received funding from the Gates Foundation to detect the polio virus via paper-based diagnostics. Polio is still found in countries on the continents of Asia and Africa.

I have previously mentioned Linsey Marr in an Oct. 18, 2013 post about the revival of the Nanotechnology Consumer Products Inventory (originally developed by the Project for Emerging Nanotechnologies) by academics at Virginia Tech and first mentioned CEINT in an Aug. 15, 2011 post about a special project featuring a mesocosm at Duke University (North Carolina).

Graphene not so impermeable after all

I saw the news last week but it took reading Dexter Johnson’s Dec. 2, 2014 post for me to achieve a greater understanding of why graphene’s proton permeability is such a big deal and of the tensions underlying graphene research in the UK.

Let’s start with the news, from a Nov. 26, 2014 news item on Nanowerk (Note: A link has been removed),

Published in the journal Nature (“Proton transport through one-atom-thick crystals”), the discovery could revolutionise fuel cells and other hydrogen-based technologies as they require a barrier that only allow protons – hydrogen atoms stripped off their electrons – to pass through.

In addition, graphene membranes could be used to sieve hydrogen gas out of the atmosphere, where it is present in minute quantities, creating the possibility of electric generators powered by air.

A Nov. 26, 2014 University of Manchester news release, which originated the news item, describes the research in greater detail,

One-atom thick material graphene, first isolated and explored in 2004 by a team at The University of Manchester, is renowned for its barrier properties, which has a number of uses in applications such as corrosion-proof coatings and impermeable packaging.

For example, it would take the lifetime of the universe for hydrogen, the smallest of all atoms, to pierce a graphene monolayer.

Now a group led by Sir Andre Geim tested whether protons are also repelled by graphene. They fully expected that protons would be blocked, as existing theory predicted as little proton permeation as for hydrogen.

Despite the pessimistic prognosis, the researchers found that protons pass through the ultra-thin crystals surprisingly easily, especially at elevated temperatures and if the films were covered with catalytic nanoparticles such as platinum.

The discovery makes monolayers of graphene, and its sister material boron nitride, attractive for possible uses as proton-conducting membranes, which are at the heart of modern fuel cell technology. Fuel cells use oxygen and hydrogen as a fuel and convert the input chemical energy directly into electricity. Without membranes that allow an exclusive flow of protons but prevent other species to pass through, this technology would not exist.

Despite being well-established, fuel-cell technology requires further improvements to make it more widely used. One of the major problems is a fuel crossover through the existing proton membranes, which reduces their efficiency and durability.

The University of Manchester research suggests that the use of graphene or monolayer boron nitride can allow the existing membranes to become thinner and more efficient, with less fuel crossover and poisoning. This can boost competitiveness of fuel cells.

The Manchester group also demonstrated that their one-atom-thick membranes can be used to extract hydrogen from a humid atmosphere. They hypothesise that such harvesting can be combined together with fuel cells to create a mobile electric generator that is fuelled simply by hydrogen present in air.

Marcelo Lozada-Hidalgo, a PhD student and corresponding author of this paper, said: “When you know how it should work, it is a very simple setup. You put a hydrogen-containing gas on one side, apply small electric current and collect pure hydrogen on the other side. This hydrogen can then be burned in a fuel cell.

“We worked with small membranes, and the achieved flow of hydrogen is of course tiny so far. But this is the initial stage of discovery, and the paper is to make experts aware of the existing prospects. To build up and test hydrogen harvesters will require much further effort.”

Dr Sheng Hu, a postdoctoral researcher and the first author in this work, added: “It looks extremely simple and equally promising. Because graphene can be produced these days in square metre sheets, we hope that it will find its way to commercial fuel cells sooner rather than later”.

The work is an international collaboration involving groups from China and the Netherlands who supported theoretical aspects of this research. Marcelo Lozada-Hidalgo is funded by a PhD studentship programme between the National Council of Science and Technology of Mexico and The University of Manchester.

Here’s more about the research and its implications from Dexter Johnson’s Dec. 2, 2014 post on the Nanoclast blog on the IEEE (Institute of Electronics and Electrical Engineers) website (Note: Links have been removed),

This latest development alters the understanding of one of the key properties of graphene: that it is impermeable to all gases and liquids. Even an atom as small as hydrogen would need billions of years for it to pass through the dense electronic cloud of graphene.  In fact, it is this impermeability that has made it attractive for use in gas separation membranes.

But as Geim and his colleagues discovered, in research that was published in the journal Nature, monolayers of graphene and boron nitride are highly permeable to thermal protons under ambient conditions. So hydrogen atoms stripped of their electrons could pass right through the one-atom-thick materials.

The surprising discovery that protons could breach these materials means that that they could be used in proton-conducting membranes (also known as proton exchange membranes), which are central to the functioning of fuel cells. Fuel cells operate through chemical reactions involving hydrogen fuel and oxygen, with the result being electrical energy. The membranes used in the fuel cells are impermeable to oxygen and hydrogen but allow for the passage of protons.

Dexter goes into more detail about hydrogen fuel cells and why this discovery is so exciting. He also provides some insight into the UK’s graphene community (Note: A link has been removed),

While some have been frustrated that Geim has focused his attention on fundamental research rather than becoming more active in the commercialization of graphene, he may have just cracked open graphene’s greatest application possibility to date.

I recommend reading Dexter’s post if you want to learn more about fuel cell technology and the impact this discovery may have.

Richard Van Noorden’s Nov. 27, 2014 article for Nature provides another perspective on this work,

Fuel-cell experts say that the work is proof of principle, but are cautious about its immediate application. Factors such as to how grow a sufficiently clean, large graphene sheet, and its cost and lifetime, would have to be taken into account. “It may or may not be a better membrane for a fuel cell,” says Andrew Herring, a chemical engineer at the Colorado School of Mines in Golden.

Van Noorden also writes about another graphene discovery from last week, which won’t be featured here. Where graphene is concerned I have to draw a line or else this entire blog would be focused on that material alone.

Getting back back to permeability, graphene, and protons, here’s a link to and a citation for the research paper,

Proton transport through one-atom-thick crystals by S. Hu, M. Lozada-Hidalgo, F. C. Wang, A. Mishchenko, F. Schedin, R. R. Nair, E. W. Hill, D. W. Boukhvalov, M. I. Katsnelson, R. A. W. Dryfe, I. V. Grigorieva, H. A. Wu, & A. K. Geim. Nature (2014 doi:10.1038/nature14015 Published online 26 November 2014

This article is behind a paywall.

Legos, geckos (van der Waals force), and single-atom sheets at the University of Kansas (US)

A Nov. 25, 2014 news item on Nanowerk describes the achievement,

Physicists at the University of Kansas have fabricated an innovative substance from two different atomic sheets that interlock much like Lego toy bricks. The researchers said the new material — made of a layer of graphene and a layer of tungsten disulfide — could be used in solar cells and flexible electronics. …

Hsin-Ying Chiu, assistant professor of physics and astronomy, and graduate student Matt Bellus fabricated the new material using “layer-by-layer assembly” as a versatile bottom-up nanofabrication technique. Then, Jiaqi He, a visiting student from China, and Nardeep Kumar, a graduate student who now has moved to Intel Corp., investigated how electrons move between the two layers through ultrafast laser spectroscopy in KU’s Ultrafast Laser Lab, supervised by Hui Zhao, associate professor of physics and astronomy.

“To build artificial materials with synergistic functionality has been a long journey of discovery,” Chiu said. “A new class of materials, made of the layered materials, has attracted extensive attention ever since the rapid development of graphene technology. One of the most promising aspects of this research is the potential to devise next-generation materials via atomic layer-level control over its electronic structure.”

A Nov. 25, 2014 University of Kansas news release (also on EurekAlert), which originated the news item, describes the problems and the new technique in more detail,

According to the researchers, the approach is to design synergistic materials by combining two single-atom thick sheets, for example, acting as a photovoltaic cell as well as a light-emitting diode, converting energy between electricity and radiation. However, combining layers of atomically thin material is a thorny task that has flummoxed researchers for years.

“A big challenge of this approach is that, most materials don’t connect together because of their different atomic arrangements at the interface — the arrangement of the atoms cannot follow the two different sets of rules at the same time,” Chiu said. “This is like playing with Legos of different sizes made by different manufacturers. As a consequence, new materials can only be made from materials with very similar atomic arrangements, which often have similar properties, too. Even then, arrangement of atoms at the interface is irregular, which often results in poor qualities.”

Layered materials such as those developed by the KU researchers provide a solution for this problem. Unlike conventional materials formed by atoms that are strongly bound in all directions, the new material features two layers where each atomic sheet is composed of atoms bound strongly with their neighbors — but the two atomic sheets are themselves only weakly linked to each other by the so-called van der Waals force, the same attractive phenomenon between molecules that allows geckos to stick to walls and ceilings.

“There exist about 100 different types of layered crystals — graphite is a well-known example,” Bellus said. “Because of the weak interlayer connection, one can choose any two types of atomic sheets and put one on top of the other without any problem. It’s like playing Legos with a flat bottom. There is no restriction. This approach can potentially product a large number of new materials with combined novel properties and transform the material science.”

Chiu and Bellus created the new carbon and tungsten disulfide material with the aim of developing novel materials for efficient solar cells. The single sheet of carbon atoms, known as graphene, excels at moving electrons around, while a single-layer of tungsten disulfide atoms is good at absorbing sunlight and converting it to electricity. By combining the two, this innovative material can potentially perform both tasks well.

The team used scotch tape to lift a single layer of tungsten disulfide atoms from a crystal and apply it to a silicon substrate. Next, they used the same procedure to remove a single layer of carbon atoms from a graphite crystal. With a microscope, they precisely laid the graphene on top of the tungsten disulfide layer. To remove any glue between the two atomic layers that are unintentionally introduced during the process, the material was heated at about 500 degrees Fahrenheit for a half-hour. This allowed the force between the two layers to squeeze out the glue, resulting in a sample of two atomically thin layers with a clean interface.

Doctoral students He and Kumar tested the new material in KU’s Ultrafast Laser Lab. The researchers used a laser pulse to excite the tungsten disulfide layer.

“We found that nearly 100 percent of the electrons that absorbed the energy from the laser pulse move from tungsten disulfide to graphene within one picosecond, or one-millionth of one-millionth second,” Zhao said. “This proves that the new material indeed combines the good properties of each component layer.”

The research groups led by Chiu and Zhao are trying to apply this Lego approach to other materials. For example, by combining two materials that absorb light of different colors, they can make materials that react to diverse parts of the solar spectrum.

Here’s a link to and a citation for the paper,

Electron transfer and coupling in graphene–​tungsten disulfide van der Waals heterostructures by Jiaqi He, Nardeep Kumar, Matthew Z. Bellus,     Hsin-Ying Chiu, Dawei He, Yongsheng Wang, & Hui Zhao. Nature Communications 5, Article number: 5622 doi:10.1038/ncomms6622 Published 25 November 2014

This paper is behind a paywall but there is a few preview available through ReadCube Access.