Tag Archives: Case Western Reserve University

Nanodiamond grow-ops possible now nanodiamonds can be made in ambient conditions

Living in a area where marijuana grow-ops are a serious issue and something to be considered when you buy your condo, house, etc. (dangerous people showing up at odd times and structural issues are amongst two of the most feared problems), an Oct. 22, 2013 news item on Azonano featuring nanodiamonds grown at almost room-level temperatures caught my attention,

Instead of having to use tons of crushing force and volcanic heat to forge diamonds, researchers at Case Western Reserve University [Case] have developed a way to cheaply make nanodiamonds on a lab bench at atmospheric pressure and near room temperature.

The nanodiamonds are formed directly from a gas and require no surface to grow on.

The discovery holds promise for many uses in technology and industry, such as coating plastics with ultrafine diamond powder and making flexible electronics, implants, drug-delivery devices and more products that take advantage of diamond’s exceptional properties.

Their investigation is published today in the scientific journal Nature Communications. The findings build on a tradition of diamond research at Case Western Reserve.

The Oct. 21, 2013 Case University press release (also on EurekAlert), which originated the news item, explaining why this discovery is so exciting and describing the technique for creating nanodiamonds without “crushing force and volcanic heat” in more detail,

Beyond its applications, the discovery may offer some insight into our universe: an explanation of how nanodiamonds seen in space and found in meteorites may be formed.

“This is not a complex process: ethanol vapor at room temperature and pressure is converted to diamond,” said Mohan Sankaran, associate professor of chemical engineering at Case Western Reserve and leader of the project. “We flow the gas through a plasma, add hydrogen and out come diamond nanoparticles. We can put this together and make them in almost any lab.”

The process for making these small “forever stones” won’t melt plastic so it is well suited for certain high-tech applications. Diamond, renowned for being hard, has excellent optical properties and the highest velocity of sound and thermal conductivity of any material.

Unlike the other form of carbon, graphite, diamond is a semiconductor, similar to silicon, which is the dominant material in the electronics industry, and gallium arsenide, which is used in lasers and other optical devices.

While the process is simple, finding the right concentrations and flows—what the researchers call the “sweet spot”—took time.

The other researchers involved were postdoctoral researcher Ajay Kumar, PhD student Pin Ann Lin, and undergraduate student Albert Xue, of Case Western Reserve; and physics professor Yoke Khin Yap and graduate student Boyi Hao, of Michigan Technological University.

Sankaran and John Angus, professor emeritus of chemical engineering, came up with the idea of growing nanodiamonds with no heat or pressure about eight years ago. Angus’ research in the 1960s and 1970s led him and others to devise a way to grow diamond films at low pressure and high temperature, a process known as chemical vapor deposition that is now used to make coatings on computer disks and razor blades. Sankaran’s specialty, meanwhile, is making nanoparticles using cool microplasmas.

It usually requires high pressures and high temperatures to convert graphite to diamond or a combination of hydrogen gas and a heated substrate to grow diamond rather than graphite.

“But at the nanoscale, surface energy makes diamond more stable than graphite,” Sankaran explained. “We thought if we could nucleate carbon clusters in the gas phase that were less than 5 nanometers, they would be diamond instead of graphite even at normal pressure and temperature.”

After several ups and downs with the effort, the process came together when Kumar joined Sankaran’s lab. The engineers produced diamond much like they’d produce carbon soot.

They first create a plasma, which is a state of matter similar to a gas but a portion is becoming charged, or ionized. A spark is an example of a plasma, but it’s hot and uncontrollable.

To get to cooler and safer temperatures, they ionized argon gas as it was pumped out of a tube a hair-width in diameter, creating a microplasma. They pumped ethanol—the source of carbon—through the microplasma, where, similar to burning a fuel, carbon breaks free from other molecules in the gas, and yields particles of 2 to 3 nanometers, small enough that they turn into diamond.

In less than a microsecond, they add hydrogen. The element removes carbon that hasn’t turned to diamond while simultaneously stabilizing the diamond particle surface.

The diamond formed is not the large perfect crystals used to make jewelry, but is a powder of diamond particles. Sankaran and Kumar are now consistently making high-quality diamonds averaging 2 nanometers in diameter.

The researchers spent about a year of testing to verify they were producing diamonds and that the process could be replicated, Kumar said. The team did different tests themselves and brought in Yap’s lab to analyze the nanoparticles by Raman spectroscopy.

Currently, nanodiamonds are made by detonating an explosive in a reactor vessel to provide heat and pressure. The diamond particles must then be removed and purified from contaminating elements massed around them. The process is quick and cheap but the nanodiamonds aggregate and are of varying size and purity.

The new research offers promising implications. Nanodiamonds, for instance, are being tested to carry drugs to tumors. Because diamond is not recognized as an invader by the immune system, it does not evoke resistance, the main reason why chemotherapy fails.

Sankaran said his nanodiamonds may offer an alternative to diamonds made by detonation methods because they are purer and smaller.

The group’s process produces three kinds of diamonds: about half are cubic, the same structure as gem diamonds, a small percentage are a form suspected of having hydrogen trapped inside and about half are lonsdaleite, a hexagonal form found in interstellar dust but rarely found on Earth.

A recent paper in the journal Physical Review Letters suggests that when interstellar dust collides, such high pressure is involved that the graphitic carbon turns into londsdaleite nanodiamonds.

Sankaran and Kumar contend that an alternative with no high pressure requirement, such as their method, should be considered, too.

“Maybe we’re making diamond in the way diamond is sometimes made in outer space,” Sankaran proposed. “Ethanol and plasmas exist in outer space, and our nanodiamonds are similar in size and structure to those found in space.”

The group is now investigating whether it can fine-tune the process to control which form of diamond is made, analyzing the structures and determining if each has different properties. Lonsdaleite, for instance, is harder than cubic diamond.

The researchers have made a kind of nanodiamond spray paint. “We can do this in a single step, by spraying the nanodiamonds as they are produced out of the plasma and purified with hydrogen, to coat a surface,” Kumar said.

…

“Will they be able to scale up? That’s always a crap shoot,” Angus said. “But I think it can be done, and at very high rates and cheaply. Ultimately, it may take some years to get there, but there is no theoretical reason it can’t be done.”

Here’s an image from the researchers illustrating the technique,

Caption: (Clockwise) Microplasma dissociates ethanol vapor, carbon particles are collected and dispersed in solution, and electron microscope image reveals nanosized diamond particles.
Credit: Case Western Reserve University

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

Formation of nanodiamonds at near-ambient conditions via microplasma dissociation of ethanol vapour by Ajay Kumar, Pin Ann Lin, Albert Xue, Boyi Hao, Yoke Khin Yap, & R. Mohan Sankaran. Nature Communications 4, Article number: 2618 doi:10.1038/ncomms3618 Published 21 October 2013

This article is behind a paywall,

Fuel cells break free of metal catalysts (graphene instead of platinum) with research from joint Korea-US research team

1 Reply

Fuel cells—I used to hear a lot about them as there is a company in the region, Ballard Power Systems which specializes in that field. There was a lot of excitement in the late 1990s and into the 2000s and then nothing. Given the hype of the early days, I was expecting fuel-cell-powered-cars by now. A June 5, 2013 Case Western Reserve University news release on EurekAlert may provide an answer as to why fuel cells have not been adopted more widely,

Researchers from South Korea, Case Western Reserve University and University of North Texas have discovered an inexpensive and easily produced catalyst that performs better than platinum in oxygen-reduction reactions.

The finding, detailed in Nature’s Scientific Reports online today, is a step toward eliminating what industry regards as the largest obstacle to large-scale commercialization of fuel cell technology.

Fuel cells can be more efficient than internal combustion engines, silent, and at least one type produces zero greenhouse emissions at the tail pipe. Car and bus manufacturers as well as makers of residential and small-business-sized generators have been testing and developing different forms of fuel cells for more than a decade but the high cost and insufficiencies of platinum catalysts have been the Achilles heel.

The news release goes on to provide context for the work and details about the new graphene catalyst,

Like a battery, a fuel cell converts chemical energy into electrical energy. It works by removing an electron from a fuel, usually hydrogen or methanol mixed with water, at the cell’s anode, or positive electrode, creating a current.Hydrogen ions produced then pass through a membrane to the cathode, or negative electrode. Here, oxygen molecules from the air are split and reduced by the addition of electrons and combined with the hydrogen ions to form water and heat—the only byproducts.

A better, cheaper catalyst than scarce and costly platinum is required if hydrogen fuel cells and direct methanol fuel cells are to become realistic alternatives to fossil fuels, the authors say.

The technology to make alternative catalysts builds on a simple and cheap industrial process several of the researchers developed to make graphene sheets from graphite.

Inside a ball miller, which is a canister filled with steel balls, the researchers broke graphite down into single-layer graphene nanoparticles. While the canister turned, they injected chlorine, bromine or iodine gas to produce different catalysts.

In each case, gas molecules replaced carbon atoms along the zigzag edges of nanoplatelets created by milling. Not only were the edges then favorable to binding with oxygen molecules, but the bond strength between the two oxygen atoms weakened. The weaker the oxygen bonds became, the more efficiently the oxygen was reduced and converted to water at the cathode.

In testing, a cathode coated with iodine-edged nanoplatelets performed best. A cathode coated with bromine-edged nanoparticles generated 7 percent less current than the commercial cathode coated with platinum, the chlorine-edged nanoplatelets 40 percent less.

In a test of durability, electrodes coated with the nanoplatelets maintained 85.6 percent to 87.4 percent of their initial current after 10,000 cycles while the platinum electrodes maintained only 62.5 percent.

Carbon monoxide was added to replicate the poisoning that many scientists blame for the poor performance of platinum at the cathode. The performance of the graphene-based catalysts was unaffected.

When methanol was added to replicate methanol crossover from the anode to cathode in direct methanol fuel cells, the current density of the platinum catalyst dropped sharply. Again, the graphene-based catalysts were unaffected.

One of the researchers sums up the research (from the news release),

“We made metal-free catalysts using an affordable and scalable process,” said Liming Dai, the Kent Hale Smith Professor of macromolecular science and engineering at Case Western Reserve and one of the report’s authors. “The catalysts are more stable than platinum catalysts and tolerate carbon monoxide poisoning and methanol crossover.”

And, in their initial tests, a cathode coated with one form of catalyst—graphene nanoparticles edged with iodine—proved more efficient in the oxygen reduction reaction, generating 33 percent more current than a commercial cathode coated with platinum generated.

For those who want more,

Facile, scalable synthesis of edge-halogenated graphene nanoplatelets as efficient metal-free eletrocatalysts for oxygen reduction reaction by In-Yup Jeon, Hyun-Jung Choi, Min Choi, Jeong-Min Seo, Sun-Min Jung, Min-Jung Kim, Sheng Zhang, Lipeng Zhang, Zhenhai Xia, Liming Dai, Noejung Park, & Jong-Beom Baek. Scientific Reports 3, Article number: 1810 doi:10.1038/srep01810 Published 05 June 2013

The paper is open access.

Monitoring hip and knee replacements from inside

Leave a reply

I have a fondness for the ‘My mother is a cyborg‘ posting that I wrote for April 20, 2012 largely due to the title which amuses and makes the piece easy to find. In common with this posting, ‘My mother …’ is about replacements (hip, etc.) and nanotechnology.

Before spilling the latest news, here’s the reason for all the research interest in hip replacements, from my April 20, 2012 posting,

Since her [my mother’s] operation, I’ve become somewhat interested in hip replacements. From the April 19, 2012 news item by Anne Trafton on Nanowerk about research at MIT (Massachusetts Institute of Technology),

Every year, more than a million Americans receive an artificial hip or knee prosthesis. Such implants are designed to last many years, but in about 17 percent of patients who receive a total joint replacement, the implant eventually loosens and has to be replaced early, which can cause dangerous complications for elderly patients.

To help minimize these burdensome operations, a team of MIT chemical engineers has developed a new coating for implants that could help them better adhere to the patient’s bone, preventing premature failure.

There’s a researcher at Case Western Reserve University (Ohio) who is taking a different approach (from the MIT team) by utilizing an emergent process, magnetic particle imaging, according to the Feb. 5, 2013 news item on Nanowerk,

A Case Western Reserve University chemistry professor has begun imbedding magnetic nanoparticles in the toughest of plastics to understand why more than 40,000 Americans must replace their knee and hip replacements annually.

Anna C. Samia, an assistant professor who specializes in metallic nanostructures, has been awarded a five-year $600,000 National Science Foundation-CAREER grant to create new materials and equipment to test ultra-high molecular weight polyethylene used to make artificial joints. She and her team of researchers will also develop magnetic particle imaging techniques to monitor degradation and wear.

The US National Science Foundation gives more information about Samia’s project on her ‘Magnetic Imaging Guided Composite Materials Development’ Career Award webpage including this non-technical summary I’ve excerpted,

Polyethylene is widely used as a component in the fabrication of joint prostheses. A major downside of this material is that it can undergo excessive wear leading to premature loosening of the implant, which in turn can lead to failure and complicated replacement revision surgeries. Studies have shown that polyethylene wear in artificial joint replacements are not always identical and are not easily explained by exclusively mechanical factors. In cases of premature and excessive wear of polyethylene bearings, chemical degradation and oxidation of the polymer can significantly lower its mechanical resistance and result in an accelerated wear-off process. While ex vivo studies have been conducted on previously used polyethylene acetabular cups to understand the factors contributing to implant failure, the degradation mechanism is still not completely understood. An improved assessment of the structural integrity of the polyethylene material used in implants as subjected to mechanical and chemical stress will provide valuable information on the material’s durability, and can help predict its wear and degradation over time. To study the real-time degradation of implant materials in various chemical and biological fluid environments, the proposed project aims to develop new polyethylene composite materials that can be investigated using an emerging imaging modality called magnetic particle imaging (MPI). The proposed research will transform the wear debris monitoring of polyethylene implant materials and impact annually one million people in the U.S. alone who undergo hip and knee replacement surgeries. The educational impact of this project will build on current initiatives to educate high school, undergraduate and graduate students through the development of cross-disciplinary courses and hands-on research programs that will incorporate the interplay between materials fabrication and imaging tools. Moreover, a modular “Traveling Magnetism Show” will be developed for K-12 students at four adaptive levels and will be showcased in local schools and science museums. In addition, a new “Women in Chemistry Workshop Series at CWRU” will be established to provide a mentoring and training platform for graduate and post-graduate female chemistry students. [emphasis mine] This program will facilitate monthly discussions and workshops to tackle important aspects of career advancement specific to women scientists.

Future applications are also being considered according to the news item on Nanowerk,

Beyond artificial knees and hips, Samia said the nanoparticles, methods and technologies developed in this study would also be useful for learning how stents, electrodes, artificial organs and other implants degrade inside the body.

“A lot of other materials are used for implants,” she said. “It will be interesting to study them over time.”

As per my emphasis earlier, it’s intriguing to note that Samia’s grant is also being applied to outreach and support programs for female chemistry students.

Controlling cyborg insects

FrogHeart

Commentary about nanotech, science policy and communication, society, and the arts

Tag Archives: Case Western Reserve University

Nanodiamond grow-ops possible now nanodiamonds can be made in ambient conditions

Fuel cells break free of metal catalysts (graphene instead of platinum) with research from joint Korea-US research team

Monitoring hip and knee replacements from inside

Controlling cyborg insects