Boosting hydrogen peroxide photosynthesis via a S-scheme heterojunction with interfacial electric field

Photocatalytic hydrogen peroxide (H 2 O 2 ) production provides a sustainable alternative to the anthraquinone process, but its practical application is still limited by inefficient charge separation and sluggish oxygen reduction kinetics. Herein, S-scheme BiOBr/tubular g-C 3 N 4 (TCN) heterojunctions (BC) were rationally constructed through an in-situ growth strategy to simultaneously achieve efficient solar H 2 O 2 production and antibiotic degradation. The synergistic effect of interfacial electronic interactions, band bending and the S-scheme charge-transfer mechanism promotes spatial carrier separation while maintaining the strong oxidation and reduction abilities of BiOBr and TCN, respectively. As a result, BC0.8 achieved a maximum H 2 O 2 concentration of 4754.3 μM·g −1 ·h −1 , which was 4.3 and 7.7 times higher than those of pristine TCN and BiOBr, respectively. Meanwhile, the photocatalytic system demonstrated excellent capability for simultaneous H 2 O 2 production. During the degradation of oxytetracycline and tetracycline, H 2 O 2 production rates of 4282.7 and 4182.2 μM·g −1 ·h −1 were achieved, respectively, accompanied by degradation efficiencies of 88.7% and 81.4%. These results demonstrate the feasibility of coupling solar H 2 O 2 photosynthesis with antibiotic wastewater purification. Moreover, the photocatalyst maintained excellent H 2 O 2 production performance in natural water matrices, including lake water and seawater, highlighting its practical applicability. Mechanistic investigations revealed that the enhanced photocatalytic performance originated from the synergistic effects of the S-scheme heterojunction, accelerated interfacial charge transfer and promoted selective two-electron oxygen reduction reaction. This work provides an effective strategy for integrating solar H 2 O 2 production with practical water treatment.