Tag Archives: catalysts

It’s a very ‘carbony’ time: graphene jacket, graphene-skinned airplane, and schwarzite

In August 2018, I been stumbled across several stories about graphene-based products and a new form of carbon.

Graphene jacket

The company producing this jacket has as its goal “… creating bionic clothing that is both bulletproof and intelligent.” Well, ‘bionic‘ means biologically-inspired engineering and ‘intelligent‘ usually means there’s some kind of computing capability in the product. This jacket, which is the first step towards the company’s goal, is not bionic, bulletproof, or intelligent. Nonetheless, it represents a very interesting science experiment in which you, the consumer, are part of step two in the company’s R&D (research and development).

Onto Vollebak’s graphene jacket,

Courtesy: Vollebak

From an August 14, 2018 article by Jesus Diaz for Fast Company,

Graphene is the thinnest possible form of graphite, which you can find in your everyday pencil. It’s purely bi-dimensional, a single layer of carbon atoms that has unbelievable properties that have long threatened to revolutionize everything from aerospace engineering to medicine. …

Despite its immense promise, graphene still hasn’t found much use in consumer products, thanks to the fact that it’s hard to manipulate and manufacture in industrial quantities. The process of developing Vollebak’s jacket, according to the company’s cofounders, brothers Steve and Nick Tidball, took years of intensive research, during which the company worked with the same material scientists who built Michael Phelps’ 2008 Olympic Speedo swimsuit (which was famously banned for shattering records at the event).

The jacket is made out of a two-sided material, which the company invented during the extensive R&D process. The graphene side looks gunmetal gray, while the flipside appears matte black. To create it, the scientists turned raw graphite into something called graphene “nanoplatelets,” which are stacks of graphene that were then blended with polyurethane to create a membrane. That, in turn, is bonded to nylon to form the other side of the material, which Vollebak says alters the properties of the nylon itself. “Adding graphene to the nylon fundamentally changes its mechanical and chemical properties–a nylon fabric that couldn’t naturally conduct heat or energy, for instance, now can,” the company claims.

The company says that it’s reversible so you can enjoy graphene’s properties in different ways as the material interacts with either your skin or the world around you. “As physicists at the Max Planck Institute revealed, graphene challenges the fundamental laws of heat conduction, which means your jacket will not only conduct the heat from your body around itself to equalize your skin temperature and increase it, but the jacket can also theoretically store an unlimited amount of heat, which means it can work like a radiator,” Tidball explains.

He means it literally. You can leave the jacket out in the sun, or on another source of warmth, as it absorbs heat. Then, the company explains on its website, “If you then turn it inside out and wear the graphene next to your skin, it acts like a radiator, retaining its heat and spreading it around your body. The effect can be visibly demonstrated by placing your hand on the fabric, taking it away and then shooting the jacket with a thermal imaging camera. The heat of the handprint stays long after the hand has left.”

There’s a lot more to the article although it does feature some hype and I’m not sure I believe Diaz’s claim (August 14, 2018 article) that ‘graphene-based’ hair dye is perfectly safe ( Note: A link has been removed),

Graphene is the thinnest possible form of graphite, which you can find in your everyday pencil. It’s purely bi-dimensional, a single layer of carbon atoms that has unbelievable properties that will one day revolutionize everything from aerospace engineering to medicine. Its diverse uses are seemingly endless: It can stop a bullet if you add enough layers. It can change the color of your hair with no adverse effects. [emphasis mine] It can turn the walls of your home into a giant fire detector. “It’s so strong and so stretchy that the fibers of a spider web coated in graphene could catch a falling plane,” as Vollebak puts it in its marketing materials.

Not unless things have changed greatly since March 2018. My August 2, 2018 posting featured the graphene-based hair dye announcement from March 2018 and a cautionary note from Dr. Andrew Maynard (scroll down ab out 50% of the way for a longer excerpt of Maynard’s comments),

Northwestern University’s press release proudly announced, “Graphene finds new application as nontoxic, anti-static hair dye.” The announcement spawned headlines like “Enough with the toxic hair dyes. We could use graphene instead,” and “’Miracle material’ graphene used to create the ultimate hair dye.”

From these headlines, you might be forgiven for getting the idea that the safety of graphene-based hair dyes is a done deal. Yet having studied the potential health and environmental impacts of engineered nanomaterials for more years than I care to remember, I find such overly optimistic pronouncements worrying – especially when they’re not backed up by clear evidence.

These studies need to be approached with care, as the precise risks of graphene exposure will depend on how the material is used, how exposure occurs and how much of it is encountered. Yet there’s sufficient evidence to suggest that this substance should be used with caution – especially where there’s a high chance of exposure or that it could be released into the environment.

The full text of Dr. Maynard’s comments about graphene hair dyes and risk can be found here.

Bearing in mind  that graphene-based hair dye is an entirely different class of product from the jacket, I wouldn’t necessarily dismiss risks; I would like to know what kind of risk assessment and safety testing has been done. Due to their understandable enthusiasm, the brothers Tidball have focused all their marketing on the benefits and the opportunity for the consumer to test their product (from graphene jacket product webpage),

While it’s completely invisible and only a single atom thick, graphene is the lightest, strongest, most conductive material ever discovered, and has the same potential to change life on Earth as stone, bronze and iron once did. But it remains difficult to work with, extremely expensive to produce at scale, and lives mostly in pioneering research labs. So following in the footsteps of the scientists who discovered it through their own highly speculative experiments, we’re releasing graphene-coated jackets into the world as experimental prototypes. Our aim is to open up our R&D and accelerate discovery by getting graphene out of the lab and into the field so that we can harness the collective power of early adopters as a test group. No-one yet knows the true limits of what graphene can do, so the first edition of the Graphene Jacket is fully reversible with one side coated in graphene and the other side not. If you’d like to take part in the next stage of this supermaterial’s history, the experiment is now open. You can now buy it, test it and tell us about it. [emphasis mine]

How maverick experiments won the Nobel Prize

While graphene’s existence was first theorised in the 1940s, it wasn’t until 2004 that two maverick scientists, Andre Geim and Konstantin Novoselov, were able to isolate and test it. Through highly speculative and unfunded experimentation known as their ‘Friday night experiments,’ they peeled layer after layer off a shaving of graphite using Scotch tape until they produced a sample of graphene just one atom thick. After similarly leftfield thinking won Geim the 2000 Ig Nobel prize for levitating frogs using magnets, the pair won the Nobel prize in 2010 for the isolation of graphene.

Should you be interested, in beta-testing the jacket, it will cost you $695 (presumably USD); order here. One last thing, Vollebak is based in the UK.

Graphene skinned plane

An August 14, 2018 news item (also published as an August 1, 2018 Haydale press release) by Sue Keighley on Azonano heralds a new technology for airplans,

Haydale, (AIM: HAYD), the global advanced materials group, notes the announcement made yesterday from the University of Central Lancashire (UCLAN) about the recent unveiling of the world’s first graphene skinned plane at the internationally renowned Farnborough air show.

The prepreg material, developed by Haydale, has potential value for fuselage and wing surfaces in larger scale aero and space applications especially for the rapidly expanding drone market and, in the longer term, the commercial aerospace sector. By incorporating functionalised nanoparticles into epoxy resins, the electrical conductivity of fibre-reinforced composites has been significantly improved for lightning-strike protection, thereby achieving substantial weight saving and removing some manufacturing complexities.

Before getting to the photo, here’s a definition for pre-preg from its Wikipedia entry (Note: Links have been removed),

Pre-preg is “pre-impregnated” composite fibers where a thermoset polymer matrix material, such as epoxy, or a thermoplastic resin is already present. The fibers often take the form of a weave and the matrix is used to bond them together and to other components during manufacture.

Haydale has supplied graphene enhanced prepreg material for Juno, a three-metre wide graphene-enhanced composite skinned aircraft, that was revealed as part of the ‘Futures Day’ at Farnborough Air Show 2018. [downloaded from https://www.azonano.com/news.aspx?newsID=36298]

A July 31, 2018 University of Central Lancashire (UCLan) press release provides a tiny bit more (pun intended) detail,

The University of Central Lancashire (UCLan) has unveiled the world’s first graphene skinned plane at an internationally renowned air show.

Juno, a three-and-a-half-metre wide graphene skinned aircraft, was revealed on the North West Aerospace Alliance (NWAA) stand as part of the ‘Futures Day’ at Farnborough Air Show 2018.

The University’s aerospace engineering team has worked in partnership with the Sheffield Advanced Manufacturing Research Centre (AMRC), the University of Manchester’s National Graphene Institute (NGI), Haydale Graphene Industries (Haydale) and a range of other businesses to develop the unmanned aerial vehicle (UAV), which also includes graphene batteries and 3D printed parts.

Billy Beggs, UCLan’s Engineering Innovation Manager, said: “The industry reaction to Juno at Farnborough was superb with many positive comments about the work we’re doing. Having Juno at one the world’s biggest air shows demonstrates the great strides we’re making in leading a programme to accelerate the uptake of graphene and other nano-materials into industry.

“The programme supports the objectives of the UK Industrial Strategy and the University’s Engineering Innovation Centre (EIC) to increase industry relevant research and applications linked to key local specialisms. Given that Lancashire represents the fourth largest aerospace cluster in the world, there is perhaps no better place to be developing next generation technologies for the UK aerospace industry.”

Previous graphene developments at UCLan have included the world’s first flight of a graphene skinned wing and the launch of a specially designed graphene-enhanced capsule into near space using high altitude balloons.

UCLan engineering students have been involved in the hands-on project, helping build Juno on the Preston Campus.

Haydale supplied much of the material and all the graphene used in the aircraft. Ray Gibbs, Chief Executive Officer, said: “We are delighted to be part of the project team. Juno has highlighted the capability and benefit of using graphene to meet key issues faced by the market, such as reducing weight to increase range and payload, defeating lightning strike and protecting aircraft skins against ice build-up.”

David Bailey Chief Executive of the North West Aerospace Alliance added: “The North West aerospace cluster contributes over £7 billion to the UK economy, accounting for one quarter of the UK aerospace turnover. It is essential that the sector continues to develop next generation technologies so that it can help the UK retain its competitive advantage. It has been a pleasure to support the Engineering Innovation Centre team at the University in developing the world’s first full graphene skinned aircraft.”

The Juno project team represents the latest phase in a long-term strategic partnership between the University and a range of organisations. The partnership is expected to go from strength to strength following the opening of the £32m EIC facility in February 2019.

The next step is to fly Juno and conduct further tests over the next two months.

Next item, a new carbon material.

Schwarzite

I love watching this gif of a schwarzite,

The three-dimensional cage structure of a schwarzite that was formed inside the pores of a zeolite. (Graphics by Yongjin Lee and Efrem Braun)

An August 13, 2018 news item on Nanowerk announces the new carbon structure,

The discovery of buckyballs [also known as fullerenes, C60, or buckminsterfullerenes] surprised and delighted chemists in the 1980s, nanotubes jazzed physicists in the 1990s, and graphene charged up materials scientists in the 2000s, but one nanoscale carbon structure – a negatively curved surface called a schwarzite – has eluded everyone. Until now.

University of California, Berkeley [UC Berkeley], chemists have proved that three carbon structures recently created by scientists in South Korea and Japan are in fact the long-sought schwarzites, which researchers predict will have unique electrical and storage properties like those now being discovered in buckminsterfullerenes (buckyballs or fullerenes for short), nanotubes and graphene.

An August 13, 2018 UC Berkeley news release by Robert Sanders, which originated the news item, describes how the Berkeley scientists and the members of their international  collaboration from Germany, Switzerland, Russia, and Italy, have contributed to the current state of schwarzite research,

The new structures were built inside the pores of zeolites, crystalline forms of silicon dioxide – sand – more commonly used as water softeners in laundry detergents and to catalytically crack petroleum into gasoline. Called zeolite-templated carbons (ZTC), the structures were being investigated for possible interesting properties, though the creators were unaware of their identity as schwarzites, which theoretical chemists have worked on for decades.

Based on this theoretical work, chemists predict that schwarzites will have unique electronic, magnetic and optical properties that would make them useful as supercapacitors, battery electrodes and catalysts, and with large internal spaces ideal for gas storage and separation.

UC Berkeley postdoctoral fellow Efrem Braun and his colleagues identified these ZTC materials as schwarzites based of their negative curvature, and developed a way to predict which zeolites can be used to make schwarzites and which can’t.

“We now have the recipe for how to make these structures, which is important because, if we can make them, we can explore their behavior, which we are working hard to do now,” said Berend Smit, an adjunct professor of chemical and biomolecular engineering at UC Berkeley and an expert on porous materials such as zeolites and metal-organic frameworks.

Smit, the paper’s corresponding author, Braun and their colleagues in Switzerland, China, Germany, Italy and Russia will report their discovery this week in the journal Proceedings of the National Academy of Sciences. Smit is also a faculty scientist at Lawrence Berkeley National Laboratory.

Playing with carbon

Diamond and graphite are well-known three-dimensional crystalline arrangements of pure carbon, but carbon atoms can also form two-dimensional “crystals” — hexagonal arrangements patterned like chicken wire. Graphene is one such arrangement: a flat sheet of carbon atoms that is not only the strongest material on Earth, but also has a high electrical conductivity that makes it a promising component of electronic devices.

schwarzite carbon cage

The cage structure of a schwarzite that was formed inside the pores of a zeolite. The zeolite is subsequently dissolved to release the new material. (Graphics by Yongjin Lee and Efrem Braun)

Graphene sheets can be wadded up to form soccer ball-shaped fullerenes – spherical carbon cages that can store molecules and are being used today to deliver drugs and genes into the body. Rolling graphene into a cylinder yields fullerenes called nanotubes, which are being explored today as highly conductive wires in electronics and storage vessels for gases like hydrogen and carbon dioxide. All of these are submicroscopic, 10,000 times smaller than the width of a human hair.

To date, however, only positively curved fullerenes and graphene, which has zero curvature, have been synthesized, feats rewarded by Nobel Prizes in 1996 and 2010, respectively.

In the 1880s, German physicist Hermann Schwarz investigated negatively curved structures that resemble soap-bubble surfaces, and when theoretical work on carbon cage molecules ramped up in the 1990s, Schwarz’s name became attached to the hypothetical negatively curved carbon sheets.

“The experimental validation of schwarzites thus completes the triumvirate of possible curvatures to graphene; positively curved, flat, and now negatively curved,” Braun added.

Minimize me

Like soap bubbles on wire frames, schwarzites are topologically minimal surfaces. When made inside a zeolite, a vapor of carbon-containing molecules is injected, allowing the carbon to assemble into a two-dimensional graphene-like sheet lining the walls of the pores in the zeolite. The surface is stretched tautly to minimize its area, which makes all the surfaces curve negatively, like a saddle. The zeolite is then dissolved, leaving behind the schwarzite.

soap bubble schwarzite structure

A computer-rendered negatively curved soap bubble that exhibits the geometry of a carbon schwarzite. (Felix Knöppel image)

“These negatively-curved carbons have been very hard to synthesize on their own, but it turns out that you can grow the carbon film catalytically at the surface of a zeolite,” Braun said. “But the schwarzites synthesized to date have been made by choosing zeolite templates through trial and error. We provide very simple instructions you can follow to rationally make schwarzites and we show that, by choosing the right zeolite, you can tune schwarzites to optimize the properties you want.”

Researchers should be able to pack unusually large amounts of electrical charge into schwarzites, which would make them better capacitors than conventional ones used today in electronics. Their large interior volume would also allow storage of atoms and molecules, which is also being explored with fullerenes and nanotubes. And their large surface area, equivalent to the surface areas of the zeolites they’re grown in, could make them as versatile as zeolites for catalyzing reactions in the petroleum and natural gas industries.

Braun modeled ZTC structures computationally using the known structures of zeolites, and worked with topological mathematician Senja Barthel of the École Polytechnique Fédérale de Lausanne in Sion, Switzerland, to determine which of the minimal surfaces the structures resembled.

The team determined that, of the approximately 200 zeolites created to date, only 15 can be used as a template to make schwarzites, and only three of them have been used to date to produce schwarzite ZTCs. Over a million zeolite structures have been predicted, however, so there could be many more possible schwarzite carbon structures made using the zeolite-templating method.

Other co-authors of the paper are Yongjin Lee, Seyed Mohamad Moosavi and Barthel of the École Polytechnique Fédérale de Lausanne, Rocio Mercado of UC Berkeley, Igor Baburin of the Technische Universität Dresden in Germany and Davide Proserpio of the Università degli Studi di Milano in Italy and Samara State Technical University in Russia.

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

Generating carbon schwarzites via zeolite-templating by Efrem Braun, Yongjin Lee, Seyed Mohamad Moosavi, Senja Barthel, Rocio Mercado, Igor A. Baburin, Davide M. Proserpio, and Berend Smit. PNAS August 14, 2018. 201805062; published ahead of print August 14, 2018. https://doi.org/10.1073/pnas.1805062115

This paper appears to be open access.

Curiosity Collider Cafe event: Art. Science. Cadence in Vancouver, Canada on September 26, 2018

Curiosity Collider seems to have started the fall 2018 season with a lot of oomph. They just hosted (along with Nerd Nite Vancouver and Science Slam Canada) a science bar night on September 18, 2018 (as per my September 13, 2018 posting).

Barely a week after the bar night, there’s a Collider Cafe event on September 26, 2018 (from a September 21, 2018 announcement received via email),

When science collides with music and performance,
the beat never stops!

OUR #COLLIDERCAFE IS A SPACE FOR ARTISTS, SCIENTISTS, MAKERS, AND
ANYONE INTERESTED IN ART+SCIENCE. MEET, DISCOVER, CONNECT, CREATE. Are
you curious? Join us at “Collider Cafe: Art. Science. Cadence.” to
explore how art and science intersect in the exploration of curiosity.

When: 8:00pm on Wednesday, September 26, 2018. Doors open at 7:30pm.

Where: Café Deux Soleils 2096 Commercial Drive, Vancouver, BC (Google Map).

COST: $5-10 (sliding scale) cover at the door. Proceeds will be used to
cover the cost of running this event, and to fund future Curiosity
Collider events.

With speakers:

  • Devon More, Singer-songwriter & playwright: A Musician Philosophizes Science (talk + performance)
  • Kurtis Baute, YouTuber and self-proclaimed Whimsical Scientist: Science Communication needs Imagination
  • Douglas Bevans, Artist/musician and business owner: Hot Dog Water: The Musical
  • Victoria Gibson, Integrated Media Artist: Art About Science

PLUS, interact with Victoria Gibson’s multimedia installation “Share a tweet” after the event.

Follow updates on twitter via @ccollider or #ColliderCafe.

Head to the Facebook event page – let us know you are coming and share this event with others!

Looking for more Art+Science in Vancouver?
For more Vancouver art+science events, visit the Curiosity Collider events calendar.

There you have it!

Create gold nanoparticles and nanowires with water droplets.

For some reason it took a lot longer than usual to find this research paper despite having the journal (Nature Communications), the title (Spontaneous formation …), and the authors’ names. Thankfully, success was wrested from the jaws of defeat (I don’t care if that is trite; it’s how I felt) and links, etc. follow at the end as usual.

An April 19, 2018 Stanford University news release (also on EurekAlert) spins fascinating tale,

An experiment that, by design, was not supposed to turn up anything of note instead produced a “bewildering” surprise, according to the Stanford scientists who made the discovery: a new way of creating gold nanoparticles and nanowires using water droplets.

The technique, detailed April 19 [2018] in the journal Nature Communications, is the latest discovery in the new field of on-droplet chemistry and could lead to more environmentally friendly ways to produce nanoparticles of gold and other metals, said study leader Richard Zare, a chemist in the School of Humanities and Sciences and a co-founder of Stanford Bio-X.

“Being able to do reactions in water means you don’t have to worry about contamination. It’s green chemistry,” said Zare, who is the Marguerite Blake Wilbur Professor in Natural Science at Stanford.

Noble metal

Gold is known as a noble metal because it is relatively unreactive. Unlike base metals such as nickel and copper, gold is resistant to corrosion and oxidation, which is one reason it is such a popular metal for jewelry.

Around the mid-1980s, however, scientists discovered that gold’s chemical aloofness only manifests at large, or macroscopic, scales. At the nanometer scale, gold particles are very chemically reactive and make excellent catalysts. Today, gold nanostructures have found a role in a wide variety of applications, including bio-imaging, drug delivery, toxic gas detection and biosensors.

Until now, however, the only reliable way to make gold nanoparticles was to combine the gold precursor chloroauric acid with a reducing agent such as sodium borohydride.

The reaction transfers electrons from the reducing agent to the chloroauric acid, liberating gold atoms in the process. Depending on how the gold atoms then clump together, they can form nano-size beads, wires, rods, prisms and more.

A spritz of gold

Recently, Zare and his colleagues wondered whether this gold-producing reaction would proceed any differently with tiny, micron-size droplets of chloroauric acid and sodium borohydide. How large is a microdroplet? “It is like squeezing a perfume bottle and out spritzes a mist of microdroplets,” Zare said.

From previous experiments, the scientists knew that some chemical reactions proceed much faster in microdroplets than in larger solution volumes.

Indeed, the team observed that gold nanoparticle grew over 100,000 times faster in microdroplets. However, the most striking observation came while running a control experiment in which they replaced the reducing agent – which ordinarily releases the gold particles – with microdroplets of water.

“Much to our bewilderment, we found that gold nanostructures could be made without any added reducing agents,” said study first author Jae Kyoo Lee, a research associate.

Viewed under an electron microscope, the gold nanoparticles and nanowires appear fused together like berry clusters on a branch.

The surprise finding means that pure water microdroplets can serve as microreactors for the production of gold nanostructures. “This is yet more evidence that reactions in water droplets can be fundamentally different from those in bulk water,” said study coauthor Devleena Samanta, a former graduate student in Zare’s lab and co-author on the paper.

If the process can be scaled up, it could eliminate the need for potentially toxic reducing agents that have harmful health side effects or that can pollute waterways, Zare said.

It’s still unclear why water microdroplets are able to replace a reducing agent in this reaction. One possibility is that transforming the water into microdroplets greatly increases its surface area, creating the opportunity for a strong electric field to form at the air-water interface, which may promote the formation of gold nanoparticles and nanowires.

“The surface area atop a one-liter beaker of water is less than one square meter. But if you turn the water in that beaker into microdroplets, you will get about 3,000 square meters of surface area – about the size of half a football field,” Zare said.

The team is exploring ways to utilize the nanostructures for various catalytic and biomedical applications and to refine their technique to create gold films.

“We observed a network of nanowires that may allow the formation of a thin layer of nanowires,” Samanta said.

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

Spontaneous formation of gold nanostructures in aqueous microdroplets by Jae Kyoo Lee, Devleena Samanta, Hong Gil Nam, & Richard N. Zare. Nature Communicationsvolume 9, Article number: 1562 (2018) doi:10.1038/s41467-018-04023-z Published online: 19 April 2018

Not unsurprisingly given Zare’s history as recounted in the news release, this paper is open access.

New design strategy for synthesizing metal-organic frameworks (MOFs)

A Jan. 24, 2017 news item on Nanowerk announces new research from South Korea,

The accurate interpretation of particle sizes and shapes in nanoporus materials is essential to understanding and optimizing the performance of porous materials used in many important existing and potentially new applications. However, only a few experimental techniques have been developed for this purpose.

A team of researchers, led by Professor Wonyoung Choe of Natural Science and Professor Ja Hun Kwak of Energy and Chemical Engineering [ at Ulsan National Institute of Science and Technology {UNIST}] has recently developed a novel design strategy for synthesizing various forms of functional materials, especially for metal-organic materials (MOMs).

The research team expects that this synthetic approach might open up a new direction for the development of diverse forms in MOMs, with highly advanced areas such as sequential drug delivery/release and heterogeneous cascade catalysis targeted in the foreseeable future.

A Jan. 6, 2017 UNIST press release, which originated the news item, provides more detail,

In the last decades, much research has been developed to the synthesis and design of functional materials, but only a few of them could control the walls of the interior of the particles within the nanoporous materials.

In the study, Professor Choe and his team denomstrated sequential self-assembly strategy for synthesizing various forms of MOM crystals, including double-shell hollow MOMs, based on single-crystal to single-crystal transformation from MOP to MOF.

Schematic representation of various forms of micro-/nanostructures. From left are Solid, core-shell, hollow, matryoshka, yolk-shell and multi-shell hollow structures.

Porous materials are highly utilized as catalysts or gas capture materials because they supply abundant surface active sites for chemical reaction. Although materials, like Zeolites, which can be obtained from nature, have the ability to act as catalysts for chemical reactions, they suffer from the difficulty of controlling pore sizes and shapes.

As one solution, scientists have developed self-assembled porous materials using organic molecules and metals. Metal-Organic Frameworks (MOFs) and Metal-Organic Polyhedral (MOPs) are notable examples and they both have holes all over their surfaces. MOPs dissolve easily in chemical solvent, while MOFs are practically insoluble.

“MOFs take the form of three-dimensional (3D) structure, linking metals with organic molecules, while MOPs agglomerate together to form larger clusters,” says Jiyoung Lee, the first contributor of the study and a graduate student in the combined master-doctoral program from Chemistry department.

Schematic illustration of form evolution.

Schematic illustration of form evolution.

According to the research team, this synthetic strategy also yields other forms, such as solid, core-shell, double and triple matryoshka, and single-shell hollow MOMs, thereby exhibiting form evolution in MOMs.

“The best feature of this technique is that it allows two very different substances to coexist within a single crystal,” says Professor Choe. “This technique also permits greater control over size and shape of the pore, which can be then used to regulate the entrance and exit of molecules.”

This particular synthetic approach also has the potential to generate new type of porous materials containing micropores with diameters less than 2nm, macropores with diameters between 20 to 50nm, as well as pores of larger than 50 nm. Such hierarchical pore structure plays a critical role during catalysis, adsorption, and separation processes.

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

Evolution of form in metal–organic frameworks by Jiyoung Lee, Ja Hun Kwak & Wonyoung Choe. Nature Communications 8, Article number: 14070 (2017) doi:10.1038/ncomms14070 Published online: 04 January 2017

This is an open access paper.

Making diesel cleaner

A Dec. 10, 2015 news item on Nanowerk announces a new method for producing diesel fuels (Note: A link has been removed),

Researchers from KU Leuven [Belgium] and Utrecht University [Netherlands] have discovered a new approach to the production of fuels (Nature, “Nanoscale intimacy in bifunctional catalysts for selective conversion of hydrocarbons”). Their new method can be used to produce much cleaner diesel. It can quickly be scaled up for industrial use. In 5 to 10 years, we may see the first cars driven by this new clean diesel.

A Dec. 10, 2015 KU Leuven press release, which originated the news item, provides more detail about the research,

The production of fuel involves the use of catalysts. These substances trigger the chemical reactions that convert raw material into fuel. In the case of diesel, small catalyst granules are added to the raw material to sufficiently change the molecules of the raw material to produce useable fuel.

Catalysts can have one or more chemical functions. The catalyst that was used for this particular study has two functions, represented by two different materials: a metal (platinum) and a solid-state acid. During the production process for diesel, the molecules bounce to and fro between the metal and the acid. Each time a molecule comes into contact with one of the materials, it changes a little bit. At the end of the process, the molecules are ready to be used for diesel fuel.

The assumption has always been that the metal and the solid-state acid in the catalyst should be as close together as possible. That would speed up the production process by helping the molecules bounce to and fro more quickly. Professor Johan Martens (KU Leuven) and Professor Krijn de Jong (Utrecht University) have now discovered that this assumption is incorrect. [emphasis mine] If the functions within a catalyst are nanometres apart, the process yields better molecules for cleaner fuel.

“Our results are the exact opposite of what we had expected. At first, we thought that the samples had been switched or that something was wrong with our analysis”, says Professor Martens. “We repeated the experiments three times, only to arrive at the same conclusion: the current theory is wrong. There has to be a minimum distance between the functions within a catalyst. This goes against what the industry has been doing for the past 50 years.”

The new technique can optimise quite a few molecules in diesel. Cars that are driven by this clean diesel would emit far fewer particulates and CO². The researchers believe that their method can be scaled up for industrial use with relative ease, so the new diesel could be used in cars in 5 to 10 years.

The new technique can be applied to petroleum-based fuels, but also to renewable carbon from biomass.

A fifty year old assumption has been found wrong. Interesting, non? In any event, here’s a link to and a citation for the paper,

Nanoscale intimacy in bifunctional catalysts for selective conversion of hydrocarbons by Jovana Zecevic, Gina Vanbutsele, Krijn P. de Jong, & Johan A. Martens. Nature 528, 245–248 (10 December 2015)  doi:10.1038/nature16173 Published online 09 December 2015

This paper is behind a paywall.

Combining gold and palladium for catalytic and plasmonic octopods

Hopefully I did not the change meaning when I made the title for this piece more succinct. In any event, this research comes from the always prolific Rice University in Texas, US (from a Nov. 30, 2015 news item on Nanotechnology Now),

Catalysts are substances that speed up chemical reactions and are essential to many industries, including petroleum, food processing and pharmaceuticals. Common catalysts include palladium and platinum, both found in cars’ catalytic converters. Plasmons are waves of electrons that oscillate in particles, usually metallic, when excited by light. Plasmonic metals like gold and silver can be used as sensors in biological applications and for chemical detection, among others.

Plasmonic materials are not the best catalysts, and catalysts are typically very poor for plasmonics. But combining them in the right way shows promise for industrial and scientific applications, said Emilie Ringe, a Rice assistant professor of materials science and nanoengineering and of chemistry who led the study that appears in Scientific Reports.

“Plasmonic particles are magnets for light,” said Ringe, who worked on the project with colleagues in the U.S., the United Kingdom and Germany. “They couple with light and create big electric fields that can drive chemical processes. By combining these electric fields with a catalytic surface, we could further push chemical reactions. That’s why we’re studying how palladium and gold can be incorporated together.”

The researchers created eight-armed specks of gold and coated them with a gold-palladium alloy. The octopods proved to be efficient catalysts and sensors.

A Nov. 30, 2015 Rice University news release (also on EurekAlert), which originated the news item, expands on the theme,

“If you simply mix gold and palladium, you may end up with a bad plasmonic material and a pretty bad catalyst, because palladium does not attract light like gold does,” Ringe said. “But our particles have gold cores with palladium at the tips, so they retain their plasmonic properties and the surfaces are catalytic.”

Just as important, Ringe said, the team established characterization techniques that will allow scientists to tune application-specific alloys that report on their catalytic activity in real time.

The researchers analyzed octopods with a variety of instruments, including Rice’s new Titan Themis microscope, one of the most powerful electron microscopes in the nation. “We confirmed that even though we put palladium on a particle, it’s still capable of doing everything that a similar gold shape would do. That’s really a big deal,” she said.

“If you shine a light on these nanoparticles, it creates strong electric fields. Those fields enhance the catalysis, but they also report on the catalysis and the molecules present at the surface of the particles,” Ringe said.

The researchers used electron energy loss spectroscopy, cathodoluminescence and energy dispersive X-ray spectroscopy to make 3-D maps of the electric fields produced by exciting the plasmons. They found that strong fields were produced at the palladium-rich tips, where plasmons were the least likely to be excited.

Ringe expects further research will produce multifunctional nanoparticles in a variety of shapes that can be greatly refined for applications. Her own Rice lab is working on a metal catalyst to turn inert petroleum derivatives into backbone molecules for novel drugs.

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

Resonances of nanoparticles with poor plasmonic metal tips by Emilie Ringe, Christopher J. DeSantis, Sean M. Collins, Martial Duchamp, Rafal E. Dunin-Borkowski, Sara E. Skrabalak, & Paul A. Midgley.  Scientific Reports 5, Article number: 17431 (2015)  doi:10.1038/srep17431 Published online: 30 November 2015

This is an open access paper,

Platinum catalysts and their shortcomings

The problem boils down to the fact that platinum isn’t cheap and so US Dept. of Energy research laboratories are looking for alternatives to or ways of making more efficient use of platinum according to a June 16, 2015 news item on Nanowerk,

Visions of dazzling engagement rings may pop to mind when platinum is mentioned, but a significant share of the nearly half a million pounds of the rare metalExternal link [sic] mined each year ends up in vehicle emission systems and chemical manufacturing plants. The silvery white metal speeds up or enhances reactions, a role scientists call serving as a catalyst, and platinum is fast and efficient performing this function.

Because of its outstanding performance as a catalyst, platinum plays a major role in fuel cells. Inside a fuel cell, tiny platinum particles break apart hydrogen fuel to create electricity. Leftover protons are combined with oxygen ions to create pure water.

Fuel cells could let scientists turn wind into fuel. Right now, electricity generated by wind turbines is not stored. If that energy could be converted into hydrogen to power fuel cells, it would turn a sporadic source into a continuous one.

The problem is the platinum – a scarce and costly metal. Scientists funded by the U.S. Department of Energy’s Office of Science are seeing if something more readily available, such as iron or nickel, could catalyze the reaction.

But, earth-abundant metals cannot simply be used in place of platinum and other rare metals. Each metal works differently at the atomic level. It takes basic research to understand the interactions and use that knowledge to create the right catalysts.

A June 15, 2015 US Department of Energy Office of Science news release, which originated the news item, describes various efforts,

At the Center for Molecular Electrocatalysis, an Energy Frontier Research Center, scientists are gaining new understanding of catalysts based on common metals and how they move protons, the positively charged, oft-ignored counterpart to the electron.

Center Director Morris Bullock and his colleagues showed that protons’ ability to move through the catalyst greatly influences the catalyst’s speed and efficiency. Protons move via relays — clusters of atoms that convey protons to or from the active site of catalysts, where the reaction of interest occurs. The constitution, placement, and number of relays can let a reaction zip along or grind to a halt. Bullock and his colleagues are creating “design guidelines” for building relays.

Further, the team is expanding the guidelines to examine proton movement related to the solutions and surfaces where the catalyst resides. For example, matching the proton-donating abilityExternal link [sic] of a nickel-based catalyst to that of the surrounding liquid, much like matching your clothing choice with the event you’re attending, eases protons’ travels. The benefit? Speed. A coordinated catalyst pumped out 96,000 hydrogen molecules a second — compared to just 27,000 molecules a second without the adjustment.

This and other research at the Energy Frontier Research Center is funded by the DOE Office of Science’s Office of Basic Energy Sciences. The Center is led by Pacific Northwest National Laboratory.

At two other labs, research shows how changing the catalyst’s superstructure, which contains the proton relays and wraps around the active site, can also increase the speed of the reaction. Led by Argonne National Lab’s Vojislav Stamenkovic and Berkeley Lab’s Peidong Yang, researchers created hollow platinum and nickel nanoparticles, a thousand times smaller in diameter than a human hair. The 12-sided particles split oxygen molecules into charged oxygen ions, a reaction that’s needed in fuel cells. The new catalyst is far more active and uses far less platinum than conventional platinum-carbon catalysts.

Building the catalysts begins with tiny structures made of platinum and nickel held in solution. Oxygen from the air dissolves into the liquid and selectively etches away some of the nickel atoms. The result is a hollow framework with a highly active platinum skin over the surface. The open design of the catalyst allows the oxygen to easily access the platinum. The new catalyst has a 36-fold increase in activity compared to traditional platinum–carbon catalysts. Further, the new hollow structure continues to work far longer in operating fuel cells than traditional catalysts.

I think we’re entering the ‘slow’ season newswise so there are likely to be more of these ’roundup’ pieces being circulated in the online nanosciencesphere and, consequently, here. too.

Canadian and Japanese researchers create new technique for using iron nanoparticles in greener hydrogenation process

McGill University’s Audrey Moores and her team’s latest green chemistry work with researchers at RIKEN (The Institute of Physical and Chemical Research, Wako, Japan) and the Institute for Molecular Science (Okazaki, Japan) is featured in a June 27, 2013 news item on Nanowerk,

Researchers from McGill University, RIKEN (The Institute of Physical and Chemical Research, Wako, Japan) and the Institute for Molecular Science (Okazaki, Japan) have discovered a way to make the widely used chemical process of hydrogenation more environmentally friendly – and less expensive.

Hydrogenation is a chemical process used in a wide range of industrial applications, from food products, such as margarine, to petrochemicals and pharmaceuticals. The process typically involves the use of heavy metals, such as palladium or platinum, to catalyze the chemical reaction. While these metals are very efficient catalysts, they are also non-renewable, costly, and subject to sharp price fluctuations on international markets.

Because these metals are also toxic, even in small quantities, they also raise environmental and safety concerns. Pharmaceutical companies, for example, must use expensive purification methods to limit residual levels of these elements in pharmaceutical products. Iron, by contrast, is both naturally abundant and far less toxic than heavy metals.

Previous work by other researchers has shown that iron nanoparticles — tiny pieces of metallic iron — can be used to activate the hydrogenation reaction. Iron, however, has a well-known drawback: it rusts in the presence of oxygen or water. When rusted, iron nanoparticles stop acting as hydrogenation catalysts. This problem, which occurs with so much as trace quantities of water, has prevented iron nanoparticles from being used in industry.

The June 27, 2013 McGill University news release on EurekAlert, which originated the news item, provides details about the new technique,

The key to this new method is to produce the particles directly inside a polymer matrix, composed of amphiphilic polymers based on polystyrene and polyethylene glycol. The polymer acts as a wrapping film that protects the iron surface from rusting in the presence of water, while allowing the reactants to reach the water and react.

This innovation enabled the researchers to use iron nanoparticles as catalyst in a flow system, raising the possibility that iron could be used to replace platinum-series metals for hydrogenation under industrial conditions.

“Our research is now focused on achieving a better understanding of how the polymers are protecting the surface of the iron from water, while at the same time allowing the iron to interact with the substrate,” says Audrey Moores, an assistant professor of chemistry at McGill and co-corresponding author of the paper.

“The approach we have developed through this collaboration could lead to more sustainable industrial processes,” says Prof. Uozumi [Prof. Yasuhiro Uozumi of Riken]. “This technique provides a system in which the reaction can happen over and over with the same small amount of a catalytic material, and it enables it to take place in almost pure water — the green solvent par excellence.”

I last wrote about greener chemistry and iron nanoparticles in a March 28, 2012 posting concerning some work at the University of Toronto while the last time McGill, green chemistry, and Audrey Moores were mentioned here was in a Jan. 10, 2011 posting concerning ‘nanomagnetics.

For those who are interested in this latest work from McGill, here’s a link to and a citation for the published paper,

Highly efficient iron(0) nanoparticle-catalyzed hydrogenation in water in flow by Reuben Hudson, Go Hamasaka, Takao Osako, Yoichi M. A. Yamada, Chao-Jun Li, Yasuhiro Uozumi, and Audrey Moores.
Green Chem., 2013, Advance Article DOI: 10.1039/C3GC40789F

First published online 27 Jun 2013

This paper is behind a paywall.

Get the platinum out

They’ve been using platinum catalysts, in fuel cells and metal-air batteries, which over the last five years has ranged in cost from just under $800/oz to over $2200/oz. My March 13, 2012 posting about fuel cells noted that the use of expensive metals that are not very efficient catalysts was holding back their development and entry into the marketplace,

Advances in fuel-cell technology have been stymied by the inadequacy of metals studied as catalysts. The drawback to platinum, other than cost, is that it absorbs carbon monoxide in reactions involving fuel cells powered by organic materials like formic acid. A more recently tested metal, palladium, breaks down over time.

Now chemists at Brown University have created a triple-headed metallic nanoparticle that they say outperforms and outlasts all others at the anode end in formic-acid fuel-cell reactions.

Another group of researchers at Stanford University and other institutions is suggesting an alternative to a platinum catalyst, a multi-walled carbon nanotube. From the May 27, 2012 news release written by Mark Shwartz on EurekAlert,

Multi-walled carbon nanotubes riddled with defects and impurities on the outside could replace some of the expensive platinum catalysts used in fuel cells and metal-air batteries, according to scientists at Stanford University. Their findings are published in the May 27 online edition of the journal Nature Nanotechnology.

“Platinum is very expensive and thus impractical for large-scale commercialization,” said Hongjie Dai, a professor of chemistry at Stanford and co-author of the study. “Developing a low-cost alternative has been a major research goal for several decades.”

For the study, the Stanford team used multi-walled carbon nanotubes consisting of two or three concentric tubes nested together. The scientists showed that shredding the outer wall, while leaving the inner walls intact, enhances catalytic activity in nanotubes, yet does not interfere with their ability to conduct electricity.

“A typical carbon nanotube has few defects,” said Yanguang Li, a postdoctoral fellow at Stanford and lead author of the study. “But defects are actually important to promote the formation of catalytic sites and to render the nanotube very active for catalytic reactions.”

Here’s how it works, from the May 27, 2012 news release on EurekAlert,

For the study, Li and his co-workers treated multi-walled nanotubes in a chemical solution. Microscopic analysis revealed that the treatment caused the outer nanotube to partially unzip and form nanosized graphene pieces that clung to the inner nanotube, which remained mostly intact.

“We found that adding a few iron and nitrogen impurities made the outer wall very active for catalytic reactions,” Dai said. “But the inside maintained its integrity, providing a path for electrons to move around. You want the outside to be very active, but you still want to have good electrical conductivity. If you used a single-wall carbon nanotube you wouldn’t have this advantage, because the damage on the wall would degrade the electrical property.”

These are two different perspectives on the reason for why fuel cells and other batteries have not had the expected impact on the marketplace. The team at Brown University states the problem as an issue with the effectiveness of the metal catalysts where the Stanford-led team states the problem as being the cost of the metal used. Dexter Johnson in a March 9, 2012 posting on the Nanoclast blog on the IEEE (Institute of Electrical and Electronics Engineers) website suggested a third issue,

One of the fundamental problems with fuel cells has been the cost of producing hydrogen. While hydrogen is, of course, the most abundant element, it attaches itself to other elements like nitrogen or fluorine, and perhaps most ubiquitously to oxygen to create the water molecule. The process used to separate hydrogen out into hydrogen gas for powering fuel cells now relies on electricity produced from fossil fuels, negating some of the potential environmental benefits.

In his May 30, 2012 posting about this new work from Stanford, Dexter notes yet another issue impeding widespread commercialization,

… but the two main issues that have prevented fuel cells from gaining wider adoption—at least in the area of powering automobiles—are the costs of isolating hydrogen and building an infrastructure that would deliver that hydrogen to the automobiles.

Dexter mentions another application (metal-air batteries) that may benefit more from this latest work (from Dexter’s May 30, 2012 posting),

I think it’s all together possible that researchers at IBM and the US national labs who have been working on metal-air batteries for years now might be somewhat more interested in this line of research than fuel-cell manufacturers.

As one of the researchers notes (from the May 27, 2012 news release on EurekAlert),

“Lithium-air batteries are exciting because of their ultra-high theoretical energy density, which is more than 10 times higher than today’s best lithium ion technology,” Dai said. “But one of the stumbling blocks to development has been the lack of a high-performance, low-cost catalyst. Carbon nanotubes could be an excellent alternative to the platinum, palladium and other precious-metal catalysts now in use.”

The Stanford team made one other discovery as they were testing the carbon nanotubes,

The Stanford study might also have resolved a long-standing scientific controversy about the chemical structure of catalytic active sites where oxygen reactions occur. “One group of scientists believes that iron impurities are bonded to nitrogen at the active site,” Li said. “Another group believes that iron contributes virtually nothing, except to promote active sites made entirely of nitrogen.”

To address the controversy, the Stanford team enlisted scientists at Oak Ridge National Laboratory to conduct atomic-scale imaging and spectroscopy analysis of the nanotubes. The results showed clear, visual evidence of iron and nitrogen atoms in close proximity.

“For the first time, we were able to image individual atoms on this kind of catalyst,” Dai said. “All of the images showed iron and nitrogen close together, suggesting that the two elements are bonded. This kind of imaging is possible, because the graphene pieces are just one-atom thick.”

Dai noted that the iron impurities, which enhanced catalytic activity, actually came from metal seeds that were used to make the nanotubes and were not intentionally added by the scientists. The discovery of these accidental yet invaluable bits of iron offered the researchers an important lesson. “We learned that metal impurities in nanotubes must not be ignored,” Dai said.

Greener catalysts with iron nanoparticles

A research team at the University of Toronto has announced the discovery of a possible ‘green’ alternative to commonly used catalysts in the food, drug, and fragrance industries. From the March 27, 2012 news item on Nanowerk,

A chemistry team at the University of Toronto has discovered environmentally-friendly iron-based nanoparticle catalysts that work as well as the expensive, toxic, metal-based catalysts that are currently in wide use by the drug, fragrance and food industry.

“It is always important to strive to make industrial syntheses more green, and using iron catalysts is not only much less toxic, but it is also much more cost effective,” said Jessica Sonnenberg, a PhD student and lead author of a paper published this week in the Journal of the American Chemical Society (“Iron Nanoparticles Catalyzing the Asymmetric Transfer Hydrogenation of Ketones”).

The March 27, 2012 University of Toronto news release provides a quote from Sonnenberg which suggests there’s still a lot more work to be done before the toxic metal-based catalysts currently being used could be replaced,

… “Catalysts, even cheap iron ones developed for these types of reaction, still suffer one major downfall,” explained Sonnenberg.  “They require a one-to-one ratio of very expensive organic ligands – the molecule that binds to the central metal atom of a chemical compound – to yield catalytic activity. Our discovery of functional surface nanoparticles opens the door to using much smaller ratios of these expensive compounds relative to the metal centres.  This drastically reduces the overall cost of the transformations.”

This work at the University of Toronto reminded me of another team also working on green catalysts for chemical reactions and also based in Canada, this time at McGill University. The McGill team lead by Chao-Jun Li was mentioned most recently here in a Jan. 10, 2011 posting where their ‘nanomagnetics’ technology to replace the current toxic catalysts  is described.