Regulating exciton binding energy in resorcinol-formaldehyde resin via S-scheme heterojunction construction for efficient full-spectrum-driven H2O2 production

Photocatalytic hydrogen peroxide (H2O2) production using resorcinol-formaldehyde (RF) resin offers a sustainable strategy, but its efficiency is limited by high exciton binding energy, suppressing free charge carriers generation. Herein, an S-scheme heterojunction composed of RF and MgIn2S4 (RF/MIS) was constructed to minimize exciton binding energy by modulating charge transfer pathways. The well-designed S-scheme charge transfer mechanism facilitates photoexcited carrier separation, strengthening redox capability driven by the interfacial electric field. In situ irradiation X-ray photoelectron spectroscopy, temperature-dependent photoluminescence, and photoelectrochemical measurements reveal that the reduced exciton binding energy leads to enhanced oxygen reduction efficiency. The optimized RF/MIS achieves significant H2O2 production rates of 892.6 μmol·L-1·h-1 under full-spectrum (320-780 nm), specifically producing 18.2 μmol·L-1·h-1 of H2O2 under 730 nm irradiation, along with superior stability in consecutive recycling tests. The two-electron reduction mechanism is evidenced by electron paramagnetic resonance spectroscopy and rotating ring-disk electrode analysis. These findings establish fundamental connections between heterointerface-trapped exciton dynamics and photocatalytic efficiency, providing new directions for designing high-performance organic semiconductors.