Photoelectrochemical CO2 Reduction by a Molecular Cobalt(II) Catalyst on Planar and Nanostructured Si Surfaces

In the presence of a molecular Co-II catalyst, CO2 reduction occurred at much less negative potentials on Si photoelectrodes than on an Au electrode. The addition of 1% H2O significantly improved the performance of the CoII catalyst. Photovoltages of 580 and 320 mV were obtained on Si nanowires and a planar Si photoelectrode, respectively. This difference likely originated from the fact that the multifaceted Si nanowires are better in light harvesting and charge transfer than the planar Si surface.