Sunny Forecast For Fuel Cells

Novel electrode materials bring large-scale use of solar power closer to reality

by Steve Ritter

BY MOST SCIENTISTS' estimations, the only way to meet future global energy demand in an environmentally friendly way is by tapping into the sun's energy. Two research groups now report significant breakthroughs in electrode materials that may speed up the widespread use of fuel cells, which could be essential to a solar-powered future.

MIT/NSF

Cobalt phosphate electrode material deposited on a conducting glass electrode (bottom) efficiently splits water in an electrolysis cell set up in Nocera's MIT lab (top).

MIT's Daniel G. Nocera and Matthew W. Kanan devised a novel cobalt phosphate catalyst that forms in situ on the surface of an indium tin oxide electrode (Science, DOI: 10.1126/science.1162018). The catalyst is made from inexpensive cobalt salts and potassium phosphate buffer at neutral pH. The researchers demonstrate that even when using relatively small amounts of electricity, it can easily split water on one side of an electrolysis cell at room temperature to form oxygen. Hydrogen ions released in the process are transported by phosphate to the other side of the cell, where they are reduced to H2 at a different electrode.

Splitting water is a key step in realizing a large-scale method to collect energy from the sun using photovoltaic cells and storing it in the form of oxygen and hydrogen that can be later used to power fuel cells. The new cobalt-based electrocatalyst is a vast departure from expensive platinum-based systems that require strongly basic or acidic conditions, operate at high temperature, and may never be economically viable on an industrial scale. It sets up plain water "as a fuel for the future," Nocera says, "to be obtained under environmentally benign and low-cost conditions."

"Efficiently converting solar energy to hydrogen fuel by water splitting is a grand challenge, which could provide a fuel that is produced and used without harm to the environment," says materials scientist Ray H. Baughman of the University of Texas, Dallas. "The pioneering work of the MIT team on developing improved catalysts might be a key part of this energy solution."

http://pubs.acs.org/cen/news/86/i31/8631notw.html