Atomically Dispersed Janus Nickel Sites on Red Phosphorus for Photocatalytic Overall Water Splitting

Single‐atom nickel catalysts hold great promise for photocatalytic water splitting due to their plentiful active sites and cost‐effectiveness. Herein, we adopt a reactive‐group guided strategy to prepare atomically dispersed nickel catalysts on red phosphorus. The hydrothermal treatment of red phosphorus leads to the formation of P−H and P−OH groups, which behave as the reactive functionalities to generate the dual structure of single‐atom P−Ni and P−O−Ni catalytic sites. The produced single‐atom sites provide two different functions: P−Ni for water reduction and P−O−Ni for water oxidation. Benefitting from this specific Janus structure, Ni‐red phosphorus shows an elevated hydrogen evolution rate compared to Ni nanoparticle‐modified red phosphorus under visible‐light irradiation. The hydrogen evolution rate was additionally enhanced with increased reaction temperature, reaching 91.51 μmol h(−1) at 70 °C, corresponding to an apparent quantum efficiency of 8.9 % at 420 nm excitation wavelength.