Accelerated Interfacial Charge Transfer via Ni 3 <i>d</i> ‐S 3 <i>p</i> Orbital Hybridization in a CdS/NiPc S‐Scheme Heterojunction for Highly‐Selective H ₂ O ₂ Photosynthesis

Abstract

ABSTRACT The rapid recombination of photogenerated charge carriers severely restricts the efficiency of photocatalytic H 2 O 2 production. While S‐scheme heterojunctions can prominently promote charge separation and transfer, the atomic‐level mechanism of interfacial charge transfer remains inadequately understood. Herein, a prototype cadmium sulfide/nickel phthalocyanine (CdS/NiPc) S‐scheme heterojunction photocatalyst with interfacial Ni─S bonds was fabricated via a facile one‐step hydrothermal method. The Ni─S bond serves as an atomic‐scale charge transfer channel through Ni 3 d ‐S 3 p orbital hybridization, significantly accelerating oriented charge migration across the interface. Consequently, the optimized CdS/NiPc‐10% achieves a remarkable H 2 O 2 production rate of 34.4 mmol·L −1 ·g −1 ·h −1 , along with excellent cycling stability. Combined X‐ray absorption fine structure (XAFS), in situ irradiated X‐ray photoelectron spectroscopy (ISIXPS), and femtosecond transient absorption spectroscopy (fs‐TAS) analysis confirm the existence of Ni─S bond and dominant S‐scheme charge transport pathway. Moreover, density functional theory (DFT) calculations and electron paramagnetic resonance (EPR) spectra reveal that the Ni 3 d ‐S 3 p orbital hybridization adjusts the O 2 adsorption configuration from Yeager‐type to Pauling‐type, suppressing O─O bond cleavage and stabilizing the *OOH intermediate, thereby promoting the two‐electron oxygen reduction pathway for selective H 2 O 2 production. This work elucidates how interfacial chemical bonds regulate charge dynamics via orbital hybridization, offering new insights for designing efficient S‐scheme photocatalysts.