Rational interfacial design of mesoporous g-C₃N₄/CdMoSe quantum dots heterostructures for enhanced photocatalysis

Designing heterostructure interfaces offers a viable strategy for overcoming inefficient charge separation and transport in semiconductor photocatalysts. Herein, we report the facile construction of CdMoSe (CMS) quantum dots (QDs) decorated mesoporous graphitic carbon nitride (MCN) nanohybrids (CMS-MCN) featuring pronounced interfacial electronic coupling and charge redistribution. Upon hybridization, an increased electron density is observed on the MCN surface, indicating spontaneous electron migration from CMS QDs to MCN driven by Fermi-level equilibration and the development of an interfacial built-in electric field. This electronic interaction induces a staggered band alignment, which broadens visible-light absorption and promotes directional charge separation across the heterojunction interface. Consequently, the optimized CMS-MCN exhibits an exceptional photocatalytic H₂O₂ production rate of 3945.71 μmol h^-1 g^-1 with a solar-to-chemical efficiency of 0.13%, nearly twice that of pristine MCN. Additionally, an impressive H₂ evolution rate of 14 248 µmol h^-1 g^-1, with an apparent conversion efficiency of 10.1%, is achieved, corresponding to an approximately eleven-fold enhancement. Mechanistic investigations reveal the synergistic involvement of reactive oxygen species (˙O₂^- and ˙OH), enabled by an S-scheme charge-transfer pathway that preserves strong redox potentials. Overall, the developed CMS-MCN nanohybrid highlights interfacial band-structure engineering as an effective strategy for advancing solar-driven H₂O₂ and H₂ production.