Enhanced photoelectrochemical cathodic protection performance of H2O2-treated In2O3 thin-film photoelectrode under visible light

• H2O2-treated In2O3 shows enhanced photoelectrochemical cathodic protection property.
• H2O2 treatment induces the increase of concentrations of OA and Vo in In2O3.
• The H2O2-treated In2O3 shows an enhanced visible adsorption activity.
• The increased Vo induces the negative shift of the Fermi level of In2O3.
• The increased OA promotes the photoelectric conversion of In2O3 under visible light.

In this work, a H2O2-treated indium oxide (In2O3) semiconductor material was prepared. The photoelectrochemical cathodic protection performance and the photoelectrochemical behaviors of the H2O2-treated In2O3 were investigated. Under visible light illumination, the H2O2-treated In2O3 exhibits enhanced photoelectrochemical conversion efficiency (the photoinduced current density was increased by approximately 50%) and enhanced photoelectrochemical cathodic protection performance (the photoinduced cathodic protection current density was increased by approximately 81.8%). The concentrations of adsorbed oxygen and oxygen vacancy in In2O3 were increased after H2O2 treatment, resulting in the enhancement of visible light absorption activity of the H2O2-treated In2O3. With the increase of the concentration of oxygen vacancy, the Fermi level of In2O3 negatively shifts, which promotes the photoelectrochemical cathodic protection performance of the H2O2-treated In2O3. The increased surface adsorbed oxygen groups is beneficial for capturing the photoinduced electrons, resulting in the promotion of the separation efficiency of the photogenerated electron–hole pairs and the electron transfer capability, and hence leading to the increase of the photoelectrochemical cathodic protection performance of the H2O2-treated In2O3.