Rapid Charge Transfer Endowed by Interfacial Ni‐O Bonding in S‐scheme Heterojunction for Efficient Photocatalytic H₂ and Imine Production

Abstract

Abstract Cooperative coupling of H 2 evolution with oxidative organic synthesis is promising in avoiding the use of sacrificial agents and producing hydrogen energy with value‐added chemicals simultaneously. Nonetheless, the photocatalytic activity is obstructed by sluggish electron‐hole separation and limited redox potentials. Herein, Ni‐doped Zn 0.2 Cd 0.8 S quantum dots are chosen after screening by DFT simulation to couple with TiO 2 microspheres, forming a step‐scheme heterojunction. The Ni‐doped configuration tunes the highly active S site for augmented H 2 evolution, and the interfacial Ni−O bonds provide fast channels at the atomic level to lower the energy barrier for charge transfer. Also, DFT calculations reveal an enhanced built‐in electric field in the heterojunction for superior charge migration and separation. Kinetic analysis by femtosecond transient absorption spectra demonstrates that expedited charge migration with electrons first transfer to Ni 2+ and then to S sites. Therefore, the designed catalyst delivers drastically elevated H 2 yield (4.55 mmol g −1 h −1 ) and N‐benzylidenebenzylamine production rate (3.35 mmol g −1 h −1 ). This work provides atomic‐scale insights into the coordinated modulation of active sites and built‐in electric fields in step‐scheme heterojunction for ameliorative photocatalytic performance.