Integration effect of O₂‐plasma to an excimer‐laser‐assisted metal organic deposition process for functionalization of photoelectrodes

Abstract

To prevent photocorrosion of a Cu2O photocathode, composition of a TiO2 layer onto the Cu2O is one of the most effective solutions. For crystallization of the TiO2 layer alone without heat‐damage to the underlying Cu2O layer, which is easy to oxidize to CuO, we developed the integration process of O2‐plasma and an excimer‐laser irradiation, that a metal‐organic precursor film is crystalized by irradiation of the excimer‐laser in O2‐plasma. The TiO2 layer could be crystalized with lower oxygen vacancies by the laser irradiation in O2‐plasma compared to that prepared by the irradiation in air. Furthermore, the oxidation of Cu2O to CuO was drastically restricted due to the highly crystalized TiO2 in which oxygen ions were hard to diffuse to the interface of TiO2/Cu2O. The photocorrosion of the obtained film during water reduction reaction was also restricted. This O2‐plasma integrated process is effective for selective crystallization of metal‐oxide films for functionalization of photoelectrodes.