Tag Archives: catalyst

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/