Researchers developed a platinum-free catalyst for hydrogen production for fuel cells and other applications.
Source: Phys.org
Many renewable energy sources have a higher cost than fossil fuels due to the materials needed to make them usable, such as platinum group metals (PGMs), and the high cost of storage.
A team of researchers led by Gang Wu, a professor of energy, environmental and chemical engineering at the McKelvey School of Engineering at Washington University in St. Louis is working to change that. The team is creating a heterostructure catalyst for an anion-exchange membrane water electrolyzer (AEMWE) that splits water into hydrogen and oxygen using electricity from renewable sources. They created the catalyst with two phosphides that gave them an efficient method to extract hydrogen, a valuable yet low-cost source of zero-emissions fuel. The study is published in the Journal of the American Chemical Society.
Wu’s team has been looking for alternatives to catalysts that use expensive platinum group metals. In this research, their idea began with using sunlight, wind or water to create electricity that they could then use to separate hydrogen from water.
The platinum group metals are: platinum (Pt), palladium (Pd), iridium (Ir), rhodium (Rh), ruthenium (Ru), and osmium (Os).
“Going from water to hydrogen is a very desirable way we are able to store energy for different applications,” Wu said. “Hydrogen itself can be used as an energy carrier and is useful for different chemical industries and manufacturing.”
By combining two different phosphides, the team created a composite that boosted the catalytic activity in the extraction process.
When the team integrated this combo phosphide catalyst with a nickel iron anode, their cathode outperformed a state-of-the-art cathode made with different materials as well as a PGM benchmark. In addition, they found it could operate at current industry standards for more than 1,000 hours, making it one of the most durable PGM-free cathodes for anion-exchange membrane water electrolyzers, Wu said.
“Our catalyst showed the lowest resistance across the studied potential range, which suggests the fastest hydrogen adsorption kinetics among the studied catalysts,” Wu said. “This newly achieved performance and durability metrics make our catalyst one of the most promising membrane electrode assemblies for practical anion-exchange membrane water electrolyzers.”
While the team’s experiments were done on a lab scale, they plan to investigate the feasibility of using the cathode at an industrial scale.
