Enzymes could replace platinum catalysts in hydrogen fuel cells, suggest scientists from UK and Germany. 

Fraser Armstrong and co-workers at the University of Oxford, UK, and Humboldt University, Germany, have used an enzyme as an electrocatalyst in a hydrogen fuel cell. The enzyme can catalyse the oxidation of hydrogen to water in a safe, non-flammable atmosphere of only 3% hydrogen. 

Hydrogen fuel cells traditionally require high temperatures or expensive precious metal catalysts. Enzymes that can oxidise hydrogen, called hydrogenases, can work at rates similar to some platinum catalysts, but they are often inactive in the presence of oxygen.

The group investigated enzymes from 'knallgas' bacteria, which are tolerant to oxygen and other gases that might poison traditional platinum catalysts. 'Finding a hydrogenase so selective for hydrogen that it will oxidise dilute hydrogen in air inspired us to test the concept of a fuel cell operating on safe, dilute, mixtures of hydrogen and air,' said Armstrong. 

Anthony Wedd, an expert in bioinorganic chemistry at the University of Melbourne, Australia, welcomed the work. 'A hydrogen fuel cell based upon a hydrogenase enzyme and operating in 3% hydrogen-air mixtures is a significant development,' said Wedd. 'It marries a naturally-occurring system with practical experimental conditions for the first time, making a hydrogen economy that much more feasible,' he said. 

Rebecca Gillan