Topological Semimetal Co ₃ Sn ₂ S ₂ for Visible-Light Driven Photoelectrocatalytic Water Splitting

The development of highly efficient, low-cost photoelectrocatalytic (PEC) water splitting catalysts is crucial for addressing energy consumption and environmental pollution issues. Topological semimetals (TSMs), owing to their unique band structure, high carrier mobility, and excellent intrinsic stability, are considered as promising PEC catalysts. Among them, the TSM Co 3 Sn 2 S 2 has a linear dispersion band structure and topological surface state, which can facilitate rapid carrier transport and enhance surface reaction kinetics, respectively. In this paper, Co 3 Sn 2 S 2 thin films were experimentally prepared via a magnetron sputtering method. They not only show a broad optical absorption range of 250–2000 nm but also provide a double-layer capacitance ( C dl ) value of 81.1 μF/cm 2 . As a result, under >420 nm light irradiation, the Co 3 Sn 2 S 2 film exhibits a photocurrent density of 1.25 mA/cm 2 at 1.41 V vs RHE. Accordingly, the hydrogen evolution rate reaches up to 0.323 μmol/cm 2 /h, with good stability. These findings demonstrate that the topological semimetal Co 3 Sn 2 S 2 holds significant application potential in the field of photoelectrocatalytic water splitting while also offering new insights and opportunities for the subsequent development of novel and efficient catalysts.