Hydrogen fuel cells are rapidly gaining in popularity because of their green credentials, but sourcing the gas still remains a problem. Scientists at Stanford have made a breakthrough, building a low-cost water splitting machine that uses a catalyst to produce oxygen and hydrogen gases cleanly and reliably.
This technology is of huge interest because hydrogen is an excellent fuel – burning it produces only water as a by-product, making it very eco-friendly. However, most hydrogen is collected from fossil fuels. By inventing a commercially viable way to split water, these scientists have advanced the practicality of hydrogen fuel-based technologies enormously. Yi Cui, one of the co-authors involved, described the results as “an exciting world-record performance’.
Water is split using an electrochemical cell – two electrodes are submerged in a water source and a small amount of electricity is passed through the solution. This releases pure oxygen at one electrode and hydrogen at the other. These metal electrodes each contain small amounts of a catalyst. Previous catalysts have included mixtures of expensive rare metals such as platinum. Different catalysts and conditions were needed at each electrode, making the cell designs quite complicated.
The new catalyst is an improvement in several ways. It is made from cheap materials (nickel and iron oxides). The same catalyst works for both electrodes, and the whole system works at low voltages. Finally, traditional cells rapidly degenerate to the point of uselessness. The new cell, in contrast, works well for long periods of time – over 8 days.
The group used technology borrowed from lithium ion battery research to make a catalyst with a unique texture. “Our group has pioneered the idea of using lithium-ion batteries to search for catalysts,” Cui said. “Our hope is that this technique will lead to the discovery of new catalysts for other reactions beyond water splitting.”