New Catalyst Marks Major Step in the March Toward Hydrogen Fuel

Science 1 August 2008:
Vol. 321. no. 5889, p. 620
DOI: 10.1126/science.321.5889.620

Robert F. Service
Climate change concerns, high gas prices, and a good deal of international friction would fade if scientists could learn a trick every houseplant knows: how to absorb sunlight and store its energy in chemical bonds. What's needed are catalysts capable of taking electricity and using it to split water to generate hydrogen gas, a clean fuel. Unfortunately, the catalysts discovered so far work under harsh chemical conditions, and the best ones are made from platinum, a rare and expensive metal.
No more. This week, researchers at the Massachusetts Institute of Technology (MIT) in Cambridge led by chemist Daniel Nocera report online in Science a new water-splitting catalyst that works under environmentally friendly conditions ( More important, it's made from cobalt and phosphorus, fairly cheap and abundant elements. The new catalyst needs improvements before it can solve the world's energy problems, but several outside researchers say it's a crucial development.
"This is a great result," says John Turner, an electrochemist and water-splitting expert at the National Renewable Energy Laboratory in Golden, Colorado. Thomas Moore, a chemist at Arizona State University in Tempe, goes further. "It's a big-to-giant step" in the direction of powering industrial societies with renewable fuels, he says. "I'd say it's a breakthrough." Meanwhile, on pages 671 and 676, other groups report related advances--a cheap plastic fuel cell catalyst that converts hydrogen to electricity, and a solid oxide fuel cell catalyst that operates at lower temperatures--that affect another vital component of any future solar hydrogen system.
English chemists first used electricity to split water more than 200 years ago. The reaction requires two separate catalytic steps. The first, the positively charged electrode, or anode, swipes electrons from hydrogen atoms in water molecules. The result is that protons (hydrogen atoms minus their electrons) break away from their oxygen atoms. The anode catalyst then grabs two oxygen atoms and welds them together to make O2. Meanwhile, the free protons drift through the solution to the negatively charged electrode, or cathode, where they hook up with electrons to make molecular hydrogen (H2).