Tag Archives: platinum

Tiny 4-Inch Wafer Holds One Million NanoRobots

Researchers have harnessed the latest nanofabrication techniques to create bug-shaped robots that are wirelessly powered, able to walk, able to survive harsh environments and tiny enough to be injected through an ordinary hypodermic needle.

When I was a kid, I remember looking in a microscope, and seeing all this crazy stuff going on. Now we’re building stuff that’s active at that size. We don’t just have to watch this world. You can actually play in it,” said Marc Miskin, who developed the nanofabrication techniques with his colleagues professors Itai Cohen and Paul McEuen and researcher Alejandro Cortese at Cornell University while Miskin was a postdoc in the laboratory for atomic and solid state physics there. In January, he became an assistant professor of electrical and systems engineering at the University of Pennsylvania.

Miskin will present his microscopic robot research on this week at the American Physical Society March Meeting in Boston. He will also participate in a press conference describing the work. Information for logging on to watch and ask questions remotely is included at the end of this news release.

Over the course of the past several years, Miskin and research colleagues developed a multistep nanofabrication technique that turns a 4-inch specialized silicon wafer into a million microscopic robots in just weeks. Each 70 micron long (about the width of a very thin human hair), the robots’ bodies are formed from a superthin rectangular skeleton of glass topped with a thin layer of silicon into which the researchers etch its electronics control components and either two or four silicon solar cells — the rudimentary equivalent of a brain and organs.

Robots are built massively in parallel using nanofabrication technology: each wafer holds 1 million machines

The really high-level explanation of how we make them is we’re taking technology developed by the semiconductor industry and using it to make tiny robots,” said Miskin.

Each of a robot’s four legs is formed from a bilayer of platinum and titanium (or alternately, graphene). The platinum is applied using atomic layer deposition. “It’s like painting with atoms,” said Miskin. The platinum-titanium layer is then cut into each robot’s four 100-atom-thick legs. “The legs are super strong,” he said. “Each robot carries a body that’s 1,000 times thicker and weighs roughly 8,000 times more than each leg.”

The researchers shine a laser on one of a robot’s solar cells to power it. This causes the platinum in the leg to expand, while the titanium remains rigid in turn, causing the limb to bend. The robot’s gait is generated because each solar cell causes the alternate contraction or relaxing of the front or back legs. The researchers first saw a robot’s leg move several days before Christmas 2017. “The leg just twitched a bit,” recalled Miskin. “But it was the first proof of concept — this is going to work!

Teams at Cornell and Pennsylvania are now at work on smart versions of the robots with on-board sensors, clocks and controllers. The current laser power source would limit the robot’s control to a fingernail-width into tissue. So Miskin is thinking about new energy sources, including ultrasound and magnetic fields, that would enable these robots to make incredible journeys in the human body for missions such as drug delivery or mapping the brain.

We found out you can inject them using a syringe and they survive — they’re still intact and functional — which is pretty cool,” he said.

Source: https://eurekalert.org/

Ruthenium-based Catalyst Outperforms Platinum To Produce Hydrogen

A novel ruthenium-based catalyst developed at UC Santa Cruz has shown markedly better performance than commercial platinum catalysts in alkaline water electrolysis for hydrogen production. The catalyst is a nanostructured composite material composed of carbon nanowires with ruthenium atoms bonded to nitrogen and carbon to form active sites within the carbon matrix.

The electrochemical splitting of water to produce hydrogen is a crucial step in the development of hydrogen as a clean, environmentally friendly fuel (for car or heating system). Much of the effort to reduce the cost and increase the efficiency of this process has focused on finding alternatives to expensive platinum-based catalysts. At UC Santa Cruz, researchers led by Shaowei Chen, professor of chemistry and biochemistry, have been investigating catalysts made by incorporating ruthenium and nitrogen into carbon-based nanocomposite materials. Their new findings, published February 7 in Nature Communications, not only demonstrate the impressive performance of their ruthenium-based catalyst but also provide insights into the mechanisms involved, which may lead to further improvements.

Electron microscopy of carbon nanowires co-doped with ruthenium and nitrogen shows ruthenium nanoparticles decorating the surface of the nanowires. Elemental mapping analysis shows individual ruthenium atoms within the carbon matrix (red arrows, below).









This is a clear demonstration that ruthenium can have remarkable activity in catalyzing the production of hydrogen from water,” Chen said. “We also characterized the material on the atomic scale, which helped us understand the mechanisms, and we can use these results for the rational design and engineering of ruthenium-based catalysts.

Electron microscopy and elemental mapping analysis of the material showed ruthenium nanoparticles as well as individual ruthenium atoms within the carbon matrix. Surprisingly, the researchers found that the main sites of catalytic activity were single ruthenium atoms rather than ruthenium nanoparticles.

Source: https://news.ucsc.edu/

Jell-O To Make Powerful New Hydrogen Fuel Catalyst

A cheap and effective new catalyst developed by researchers at the University of California, Berkeley, can generate hydrogen fuel from water just as efficiently as platinum, currently the best — but also most expensivewater-splitting catalyst out there.

The catalyst, which is composed of nanometer-thin sheets of metal carbide, is manufactured using a self-assembly process that relies on a surprising ingredient: gelatin, the material that gives Jell-O its jiggle.

Two-dimensional metal carbides spark a reaction that splits water into oxygen and valuable hydrogen gas. Berkeley researchers have discovered an easy new recipe for cooking up these nanometer-thin sheets that is nearly as simple as making Jell-O from a box

Platinum is expensive, so it would be desirable to find other alternative materials to replace it,” said senior author Liwei Lin, professor of mechanical engineering at UC Berkeley. “We are actually using something similar to the Jell-O that you can eat as the foundation, and mixing it with some of the abundant earth elements to create an inexpensive new material for important catalytic reactions.

The work appears in the print edition of the journal Advanced Materials.

Source: https://news.berkeley.edu/

Cheap High-Performance Catalysts For Hydrogen Electric Car

The industry has been traditionally deploying platinum alloys as catalysts for oxygen reduction, which is for example essential in fuel cells or metal-air batteries. Expensive and rare, that metal imposes strict restrictions on manufacture. Researchers at Ruhr-Universität Bochum (RUB) and Max-Planck-Institut für Eisenforschung in Germany have discovered an alloy made up of five elements that is noble metal-free and as active as platinum.  The catalytic properties of non-noble elements and their alloys are usually rather poor. To the researchers’ surprise, one alloy made up of five almost equally balanced components offer much better properties. This is because of the so-called high entropy effect. It causes multinary alloys to maintain a simple crystal structure.

Through the interaction of different neighbouring elements, new active centres are formed that present entirely new properties and are therefore no longer bound to the limited properties of the individual elements,” explains Tobias Löffler, PhD student at the RUB Chair of Analytical ChemistryCenter for Electrochemical Sciences headed by Professor Wolfgang Schuhmann. “Our research has demonstrated that this alloy might be relevant for catalysis.”

Headed by Professor Christina Scheu, the research team at the Max-Planck-Institut für Eisenforschung analysed the generated nanoparticles using transmission electron microscopy. RUB chemists determined their catalytic activity and compared it with that of platinum nanoparticles. In the process, they identified a system made of up five elements where the high entropy effect results in catalytic activity for an oxygen reduction that is similar to that of platinum. By optimising the composition further, they successfully improved the overall activity.

These findings may have far-reaching consequences for electrocatalysis in general,” surmises Wolfgang Schuhmann. The researchers are hoping to adapt the properties for any required reactions by taking advantage of the almost infinite number of possible combinations of the elements and modifications of their composition. “Accordingly, the application will not necessarily be limited to oxygen reduction,” says Ludwig. The research team has already applied for a patent.

The results are published in the journal Advanced Energy Materials.

Source: http://news.rub.de/