In the automobile industry catalytic converters are used to change combustion chemicals into less-polluting emissions and, more recently, in fuel cells to convert water into hydrogen.
The problem with catalysts, however, is that chemical reactions occur only at certain points in the material, while the bulk of the metal — often expensive platinum — is inactive and wasted. The points where chemical reactions are most prominent tend to be at the edges of the material.
According to a statement, the Berkeley chemists have now shown how to construct a more efficient catalyst and demonstrate that it can catalyse the production of hydrogen from water as readily as the most active sections of previous catalysts.
‘This is a conceptual advance in the way we think about generating hydrogen, a clean-burning fuel, from water, a sustainable source,’ said Christopher Chang, associate professor of chemistry at Berkeley. ‘Our new catalyst is just the first generation, but the research gives us and the community a path forward to thinking about how to increase the density of functional active sites so that molecules and materials can be more effective catalysts.’
Chang and his Berkeley colleagues worked with a common catalyst, molybdenite, that is less expensive than platinum and of increasing interest as a fuel cell catalyst. Composed of molybdenum and sulphur, the material catalyses reactions such as the splitting of water into hydrogen and oxygen.
When lots of these single-molecule catalysts were dumped into acidic water and seawater that contained electrodes the catalysts generated hydrogen for several days.
At the moment, creating these catalysts in the lab is more expensive than manufacturing traditional catalysts, but efforts by Chang and others to simplify the process and create materials with billions of active sites on a ridged wafer could allow cheaper, commercially viable fuel cell catalysts.