Integrating electronic structure regulation and dynamic active sites construction on NiCdS-Ni photocatalyst for efficient hydrogen evolution.

Regulating electronic structure and enriching active sites of photocatalysts are effective strategies to promote hydrogen evolution. Herein, a unique NiCdS-Ni photocatalyst, including the surface nickel (Ni) doping and atomic Ni anchoring sites, is successfully prepared by Ni ions exchange reaction (Ni+ CdS → NiCdS) and in-situ photo-induction of Ni(Ni+NiCdS→hνNiCdS-Ni), respectively. As to Ni doping, the Ni replaced cadmium (Cd) atoms introduce hybridized states around the Fermi level, modulating the electronic structure of adjacent S atoms and optimizing the photocatalytic activity of sulfur (S) atoms. Besides, photogenerated Ni atoms, anchored on unsaturated S atoms, act as charge transfer bridges to reduce Ni ions in the solution to Ni clusters (NiCdS-Ni→neNiCdS-Ni). Subsequently, the displacement reaction of Ni clusters with protons (H) spontaneously proceeds to produce hydrogen (H) in an acidic solution (NiCdS-Ni→2HH↑+Ni+NiCdS-Ni). The equilibrium of photo-deposition/dissolution of Ni clusters realizes the construction of dynamic active sites, providing sustainable reaction centers and enhancing surface redox kinetics. The NiCdS-Ni exhibits a high hydrogen evolution rate of 428 mmol·h·g with a quantum efficiency of 75.6 % at 420 nm. This work provides the optimal S electronic structure for photocatalytic H evolution and constructs dynamic Ni clusters for chemical replacement reaction. This work provides the optimal S electronic structure for photocatalytic H evolution and constructs dynamic Ni clusters for displacement reaction, opening a dual pathway for efficient water reduction.