Efficient photocatalytic synthesis of H2O2 coupled with 3,4-dihydroisoquinoline by rGO-modified CdS catalysts

Abstract

The sluggish kinetics of the water oxidation reaction fundamentally limit photocatalytic H₂O₂ generation. We address this issue by coupling the two-electron oxygen reduction reaction (2e⁻ ORR) with selective 1,2,3,4-tetrahydroisoquinoline (THIQ) oxidation. Using a reduced graphene oxide-modified CdS photocatalyst (rGO-CdS), we achieve the highly efficient co-production of 3,4-dihydroisoquinoline (DHIQ) and H₂O₂ at rates of 26.32 and 27.98 mmol·g⁻¹ h⁻¹, respectively, with excellent selectivity for DHIQ. The rGO cocatalyst enhances light absorption, facilitates electron transfer, and suppresses charge recombination, collectively enabling selective THIQ oxidation and efficient oxygen reduction. This work establishes a cooperative coupling photoredox system that significantly enhances energy utilization efficiency and enables sustainable synthesis of value-added chemicals.