Dual-functional photoredox catalysis over Ni/CdS composite

Selective photocatalytic dehydrogenation of saturated N-heterocycles represents a sustainable photoredox route for synthesizing valuable nitrogen-containing unsaturated heteroaromatic organics. Herein, we report a Ni-decorated 3D sea urchin-like CdS composite (Ni/CdS) as a dual-functional photocatalyst for the efficient and selective semi-dehydrogenation of 1,2,3,4-tetrahydroisoquinoline (THIQ) to 3,4-dihydroisoquinoline (DHIQ) coupled with H 2 evolution under visible light irradiation. The surface-decorated Ni nanoparticles significantly enhance the separation and transfer of photogenerated electron–hole pairs over Ni/CdS, and act as reactive sites for proton reduction to H 2 , thereby leading to the improved dual-functional photoredox catalysis. Mechanistic studies identify the carbon-centered radical (•CH(NH)C 8 H 8 ) as a pivotal intermediate in the photocatalytic semi-dehydrogenation of THIQ. This study establishes an effective strategy for designing noble-metal-free photocatalytic systems that integrate selective organic transformations with H 2 evolution in a cooperative manner.