Construction of Cu/SiO₂/TiO₂ Nanobowl Arrays Electrode and Its Plasmonic Water Splitting Performance

The plasmon resonance effect of the metal nanoparticles is of great benefit to improve the efficiency of solar water splitting. However, the metal Cu is easy to be oxidized, and a complex transfer process of hot electrons exits in Cu/TiO₂ interfaces. In this work, the hierarchical Cu/TiO₂ nanobowl arrays were prepared and a SiO₂ interlayer with a thickness of 10-15 nm was introduced between the interface of Cu and TiO₂. The solar water splitting performances and the mechanism of plasmonic Cu metal were investigated by combing the experiment with simulation. Results show that the Cu₂O film formed by the oxidation of Cu in Cu/TiO₂ can assist the injection of hot electrons, but has an inhibitory effect on the light absorption of Cu. It has a positive effect on enhancing light absorption and blocking hot electron migration after adding the SiO₂ interlayer. The plasmon energy transfer promotes the formation of more photogenerated electron-hole pairs. Therefore, the Cu/SiO₂/TiO₂ nanobowl arrays exhibit the enhanced photoelectrochemical performance.