Ni Vacancy and the Se/S Ratio Regulate the p‐Band Center of Hollow NiS x Se 2‐x /Phase Junction CdS to Achieve High Efficiency and Broad‐Spectrum Photocatalytic Performance

Rational design of defect engineering and interfacial built-in electric fields of photocatalysts is imperative for renewable energy conversion. Herein, a multi-strategy involving the introduction of Ni vacancies, the adjustment of the Se/S ratio, and the construction of dual junctions are employed to simultaneously realize NiS_xSe_2-x/phase junction CdS (HCC) an excellent photocatalytic activity and broad light absorption. With the help of V_Ni and the regulation of S/Se, the local electrons are redistributed to occupy more antibonding orbitals and adjust the p-band center, thus optimizing the H^* adsorption energy of the catalyst to accelerate the photocatalytic reaction kinetics. Meanwhile, the synergistic effects of phase junction and heterojunction formations generate dual built-in electric fields (BIEF), which further amplify the stepwise separation and migration of photogenerated carriers. Notably, V_Ni-NiSSe/HCC achieves an optimal H₂ evolution rate of 11.43 mmol·g^-1·h^-1 under visible light irradiation with the apparent quantum yield (AQY) at 15.3% at 420 nm, which is 53 times and 26.6 times higher than H-CdS and HCC, respectively. Additionally, it also exhibits a hydrogen evolution rate of 147 µmol·g^-1·h^-1 under near-infrared (NIR) light with λ ≥780 nm. This work provides new insight into designing robust photocatalysts by regulating the electronic states and energy states.