Synergistic Effect of Topological Semimetal TiSi and Plasmonic Cu for Enhanced Photoelectrocatalytic Water Splitting of TiO₂ Nanorod Array

Developing high-efficiency and low-cost catalysts for PEC water splitting is vital for solving the issues of energy consumption, environmental pollution, and global warming. In this study, we designed and prepared a composite photoanode TiO₂/TiSi/Cu by depositing a topological semimetal TiSi film and plasmonic Cu nanoparticles onto a TiO₂ nanorod array. Due to the synergistic effect of the topological bands of TiSi and the SPR effect of Cu, TiO₂/TiSi/Cu exhibits significantly enhanced optical absorption in the visible-light region. Under wavelength (λ) > 420 nm light irradiation, the photocurrent density of TiO₂/TiSi/Cu reaches 4.46 mA cm^-2 at 1.9 V vs RHE, about 17.84 times that of pure TiO₂. The carrier lifetime is prolonged from 25.04 ns for pure TiO₂ to 31.13 ns for TiO₂/TiSi/Cu. Furthermore, the TiO₂/TiSi/Cu photoanode demonstrates good long-term cyclic stability, with an average hydrogen production rate of 8.12 μmol cm^-2 h^-1. Our results indicate that the synergistic effect of topological semimetal TiSi and plasmonic Cu is an effective strategy to enhance the PEC performance of TiO₂. This approach could be applied to other topological catalysts, providing new opportunities for developing novel and efficient catalysts.