Spatially Decoupled Redox Pathways in 2D/2D g-C3N4/ZnIn2S4 Enable Highly Selective Aerobic Photooxidation of Biomass
Selective solar-driven aerobic oxidation of biomass derivatives into valuable chemicals under ambient conditions is pivotal for sustainable chemical manufacturing but faces challenges from the conflict between O2 activation kinetics and selective C–H bond cleavage. This work demonstrates a spatial decoupling strategy in a precisely-engineered 2D/2D g-C3N4/ZnIn2S4 architecture, where ZnIn2S4 domains selectively activate O2, while adjacent g-C3N4 modulates electron transfer to O2 and tailors 5-hydroxymethylfurfural (HMF) binding configuration for selective C–H bond cleavage. This enables efficient selective conversion of HMF to 2,5-diformylfuran (DFF) via ambient aerobic photooxidation. When used alone, ZnIn2S4 produces mixed reactive oxygen species (·O2−/·OH) due to uncontrolled electron transfer during O2 activation. In-situ spectroscopy, Kelvin probe force microscopy (KPFM) and density functional theory (DFT) calculations demonstrate that the 2D/2D heterojunction, driven by its directed electric field, selectively activates O2 into ·O2− at ZnIn2S4 domains while suppressing ·OH generation by moderate electron transfer, mitigating over-oxidation. Adjacent g-C3N4 domains precisely anchor HMF via –OH group interactions, steering selective DFF formation. This spatial decoupling achieves a remarkable HMF-to-DFF photo-conversion rate of 1517.5 μmol g−1 h−1 with 99.4% selectivity under ambient air, outperforming many reported state-of-the-art catalysts and maintaining durable cycling performance. The work establishes a spatial decoupling principle to overcome O2 activation kinetics and site competition thermodynamics, paving the way for advanced catalyst design for sustainable energy and the environment.