Electrochemical and photoelectrochemical oxygen evolution reactions by Group X hetero-metal oxides

Electrochemical and photoelectrochemical water splitting methods must be developed to establish a sustainable energy system. In this study, we prepared Group X hetero-metal oxides and studied their (photo)electrochemical properties. Their electrochemical oxygen evolution activities improved as follows: PtO << Ni/NiO < PdO + Ni/ NiO < PtOx Ni/NiO. During deposition of the nanoparticles on a nanorod-shaped TiO2 surface, we observed interesting chemical and photoelectrochemical reactivities varied by the hetero-metal oxides nanoparticles. The Group X hetero-metal oxides on the TiO2 photoanode systematically enhanced catalytic activities for the photoelectrochemical oxygen evolution reaction, while decreasing the surface charge recombination and modulating the TiO2 band gap. The Pt/PtOx + Ni/NiO hetero-metal oxides acted as the most efficient cocatalyst on the TiO2 surface with a photocurrent of 2.62 mA/cm(2) at 1.23 V vs. RHE and 70% IPCE value, which is similar to 4 times higher than a pristine TiO2.