Topological Semimetal TiSi Microrod Array for Visible-Light Driven Photoelectrocatalytic Water Splitting

Green and environmentally friendly hydrogen energy is seen as a viable alternative to traditional energy sources. A pivotal challenge in photoelectrocatalytic (PEC) water splitting for hydrogen production lies in the development of efficient and durable catalysts. Topological semimetals (TSM) have emerged as promising candidates for PEC applications due to their distinctive electronic band structure, high carrier mobility, and robust properties. Here, based on density functional calculations, TiSi is theoretically predicted as a promising TSM PEC catalyst, with linear Dirac bands around the Fermi level and near-zero free energy (ΔGH*). Moreover, TiSi films are deposited by magnetron sputtering and further patterned into a microrod array through microelectronics processes. Accompanied by the broad light absorption between 356 and 2000 nm and low charge transfer resistance, the double-layer capacitance (Cdl) is increased 1.62 times for TiSi microrods. As a result, the photocurrent density under >420 nm light irradiation is enhanced 1.75 times to 0.813 mA/cm2 at 1.23 V vs RHE for the TiSi microrod array and exhibits a good hydrogen evolution rate of 0.543 μmol/cm2/h. Our findings underscore the significant potential of TSM in PEC water splitting and might be extended to other photoelectrical applications.