Tag Archives: catalyst

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/

Highly Stable Catalyst Helps Turn Water Into Fuel

Breaking the bonds between oxygen and hydrogen in water could be a key to the creation of hydrogen in a sustainable manner, but finding an economically viable technique for this has proved difficult. Researchers report a new hydrogen-generating catalyst that clears many of the obstacles – abundance, stability in acid conditions and efficiency.

In the journal Angewandte Chemie, researchers from the University of Illinois at Urbana-Champaign report on an electrocatalytic material made from mixing metal compounds with substance called perchloric acidElectrolyzers use electricity to break water molecules into oxygen and hydrogen. The most efficient of these devices use corrosive acids and electrode materials made of the metal compounds iridium oxide or ruthenium oxide. Iridium oxide is the more stable of the two, but iridium is one of the least abundant elements on Earth, so researchers are in search of an alternative material.

Much of the previous work was performed with electrolyzers made from just two elements – one metal and oxygen,” said Hong Yang, a co-author and professor of chemical and biomolecular engineering at Illinois. “In a recent study, we found if a compound has two metal elements – yttrium and ruthenium – and oxygen, the rate of water-splitting reaction increased.”

The researchers found that when they used perchloric acid as a catalyst and let the mixture react under heat, the physical nature of the yttrium ruthenate product changed. “The material became more porous and also had a new crystalline structure, different from all the solid catalysts we made before,” said Jaemin Kim, the lead author and a postdoctoral researcher. The new porous material the team developed – a pyrochlore oxide of yttrium ruthenate – can split water molecules at a higher rate than the current industry standard. “Because of the increased activity it promotes, a porous structure is highly desirable when it comes electrocatalysts,” Yang said. “These pores can be produced synthetically with nanometer-sized templates and substances for making ceramics; however, those can’t hold up under the high-temperature conditions needed for making high-quality solid catalysts.”

Source: https://news.illinois.edu/