There seems to be a possibility that nickel compounds might help in the electrolysis of water, the reaction at the centre of hydrogen fuel cells. Researchers at the Joseph Fourier University in Grenoble, and at the French Atomic Energy Commission in Gif-sur-Yvette and attached a nickel compound that mimics hydrogenase enzymes (catalysts) and attached it to the surface of carbon nanotubes. This maximises the catalyst’s surface area. The resulting material was tested using a proton-exchange membrane and produced hydrogen from a sulphuric acid solution. The result is only 1% as efficient than commercial platinum catalysts but is stable under typical fuel cell conditions, justifying further study.1
Abstract: Interconversion of water and hydrogen in unitized regenerative fuel cells is a promising energy storage framework for smoothing out the temporal fluctuations of solar and wind power. However, replacement of presently available platinum catalysts by lower-cost and more abundant materials is a requisite for this technology to become economically viable. Here, we show that the covalent attachment of a nickel bisdiphosphine–based mimic of the active site of hydrogenase enzymes onto multiwalled carbon nanotubes results in a high–surface area cathode material with high catalytic activity under the strongly acidic conditions required in proton exchange membrane technology. Hydrogen evolves from aqueous sulfuric acid solution with very low overvoltages (20 millivolts), and the catalyst exhibits exceptional stability (more than 100,000 turnovers). The same catalyst is also very efficient for hydrogen oxidation in this environment, exhibiting current densities similar to those observed for hydrogenase-based materials.
WebElements December 12th, 2009