Hexagonal perovskites hold great potential for ceramic fuel cell technology

Researchers from the University of Aberdeen have reported that a new family of chemical compounds known as ‘hexagonal perovskites’ could be extremely beneficial for ceramic fuel cell technology and reducing global carbon emissions.

Ceramic fuel cells are highly efficient devices that convert chemical energy into electrical energy and produce very low emissions if powered by hydrogen, providing a clean alternative to fossil fuels. Another advantage of ceramic fuel cells is that they can also use hydrocarbon fuels such as methane, meaning they can act as a ‘bridging’ technology which is an important asset in terms of the move away from hydrocarbons towards cleaner energy sources.

Perovskites found promising for low-temperature ammonia production

A team of researchers from Japan's Tokyo Tech have demonstrated perovskites' potential in the production of ammonia directly from hydrogen and nitrogen. This has the potential to open up a new approach to the manufacture of this industrially and agrochemically important gas. Ammonia is used widely an industrial reagent and in the formation of agricultural fertilizers, there are also examples of it being used as a "clean" energy carrier for hydrogen gas for fuel cells.

Masaaki Kitano and his team at Tokyo Tech point out that the main barrier to a facile synthesis of ammonia from hydrogen and nitrogen gas is the surmounting the high energy barrier needed to split diatomic nitrogen. Nitrogen-fixing plants, of course, can handle this process with a range of enzymes evolved over millions of years and metals catalysts coupled with high temperatures and pressures are the mainstays of the industrial process. There have been efforts to make perovskites in which some of their oxygen atoms have been replaced with hydrogen and nitrogen ions to act as ammonia forming materials, but these too only work at a high temperature of more than 800 degrees Celsius and the reaction takes weeks to proceed to completion. These two factors had until now meant perovskites were not looking too promising as a way to create a new ammonia process.

Perovskite nickelates examined as a potential boost to electrocatalysis

Researchers at Pacific Northwest National Laboratory are evaluating perovskite-structured rare-earth nickelates as alternatives to replace two reactions that are considered a challenge when it comes to electrocatalysts: the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER). Both are important for the development of better fuel cells, metal-air batteries, and electrolytic water-splitting.

Perovskite nickelates examined as a potential boost to electrocatalysis image

Materials such as platinum, iridium oxide and ruthenium oxide are well suited for these reactions, but they are scarce and expensive. The team has been working to study perovskite-structured rare-earth nickelates (RNiO3) that can serve as bifunctional catalysts capable of performing both OER and ORR.

A new fuel cell with a perovskite-based cathode shows exceptional power density and stability

A team of researchers at Northwestern University has created a new fuel cell with a perovskite-based cathode, that offers both exceptional power densities and long-term stability at optimal temperatures.

"For years, industry has told us that the holy grail is getting fuel cells to work at 500-degrees Celsius and with high power density, which means a longer life and less expensive components," said the team. "With this research, we can now envision a path to making cost-effective fuel cells and transforming the energy landscape."

KAIST researchers use perovskites to maximize the lifespan of fuel cells

Fuel cells are a hoped to be a key future energy technology for achieving renewable energy sources that are eco-friendly and low-cost. In particular, solid oxide fuel cells composed of ceramic materials are gaining increasing amounts of attention for their ability to directly convert various forms of fuel such as biomass, LNG, and LPG to electric energy. Researchers at KAIST have relied on pervoskite materials to develop a new technique to improve the chemical stability of electrode materials that can extend their lifespan by employing minimal amounts of metals.

KAIST researchers use perovskites to maximize the lifespan of fuel cells

The core factor that determines the performance of solid oxide fuel cells is the cathode at which the reduction reaction of oxygen takes place. Conventionally, perovskite structure oxides (ABO3) are used in cathodes. However, despite the high performance of perovskite oxides at initial operation, performance degrades with time, limiting their long-term use. In particular, the condition of a high-temperature oxidation state required for cathode operation leads to a surface segregation phenomenon in which second phases such as strontium oxide (SrOx) accumulate on the surface of oxides, resulting in a decrease in electrode performance. The detailed mechanism of this phenomenon and a way to effectively inhibit it has not been suggested.