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

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 <i>via</i> 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.