Dynamic surface radical confinement in a compact CdS–CdIn2S4 semi-coherent heterojunction for highly efficient synergetic photocatalytic selective oxidation of toluene and enhanced hydrogen production

Abstract

Efficiently activating inert C–H bonds while maintaining control over the selective pathways of complex chemical reactions involving high-energy species remains a highly challenging and as-yet unattained objective. Herein, we propose a novel concept called ‘dynamic local free radical confinement-mediated mechanism’ to efficiently achieve synergetic selective oxidation of toluene and hydrogen generation for the first time via a CdS–CdIn₂S₄ semi-coherent heterojunction (CCS) under two-phase conditions. Surprisingly, the optimized CCS-2 exhibited amazing catalytic efficiency and long-term stability in gram-scale experiments and automatically separated the catalyst from the product. The mechanistic study indicates that the unstable semi-coherent interface in CCS-2 establishes a channel for directed carrier migration. Furthermore, the unstable semi-coherent interface facilitates the assembly of low-coordinate cadmium sites with surface hydroxyl groups, resulting in the formation of a first-layer hydrogen bonding framework, which effectively cleaves the C–H bond and dynamically inhibits the adsorption of aldehydes, thereby inducing spatial separation between the two phases. Our study highlights a new insight into the selective regulation mediated by surface radicals and introduces a novel and universal approach for achieving environmentally friendly chemical synthesis and energy conversion.