A highly stable, efficient visible-light driven water photoelectrolysis system using a nanocrystalline WO3 photoanode and a methane sulfonic acid electrolyte.

Nanostructuring of semiconductor films offers the potential means for producing photoelectrodes with improved minority charge carrier collection. Crucial to the effective operation of the photoelectrode is also the choice of a suitable electrolyte. The behaviour of the nanostructured WO(3) photoanodes in methane sulfonic acid solutions, which allow one to obtain large, perfectly stable visible-light driven water splitting photocurrents, is discussed. The important effect of the electrolyte concentration upon the current distribution and the related photocurrent losses within the nanoporous photoelectrodes is pointed out.