Photoanodes Based on Nanostructured WO3 for Water Splitting

Anodically grown WO3 photoelectrodes prepared in an N‐methylformamide (NMF) electrolyte have been investigated with the aim of exploring the effects induced by anodization time and water concentration in the electrochemical bath on the properties of the resulting photoanodes. An n‐type WO3 semiconductor is one of the most promising photoanodes for hydrogen production from water splitting and the electrochemical anodization of tungsten allows very good photoelectrodes, which are characterized by a low charge‐transfer resistance and an increased spectral response in the visible region, to be obtained. These photoanodes were investigated by a combination of steady state and transient photoelectrochemical techniques and a correlation between photocurrent produced, morphology, and charge transport has been evaluated. Light capture: Anodically grown WO3 electrodes show interesting properties displaying both a partial visible absorption and good charge‐transport abilities. They exhibit typical crystalline oxide nanostructures and they reach 70 % of photon‐to‐current conversion in 1 M H2SO4 at 1.5 V versus SCE under illumination (see picture).