Enhanced photocatalysis at water/toluene interfaces via amphiphilic BiOBr/g-C3N4 S-scheme heterojunctions for simultaneous production of benzaldehyde and H2O2

Coupling O 2 reduction and selective organic oxidation for photocatalytic coproduction of H 2 O 2 and value-added organic compounds (e.g., benzaldehyde) represents a dual-functional strategy to maximize solar energy utilization and economic benefits in chemical manufacturing. Employing water/organic biphasic systems for such reactions offers a sustainable solution to address the challenges inherent in conventional single-phase systems, such as energy-intensive product separation and uncontrolled secondary reactions. Herein, we rationally designed and synthesized an amphiphilic BiOBr/g-C 3 N 4 S-scheme heterojunction photocatalyst (labeled as BOB/PCN-A) composed of hierarchically structured BiOBr and porous g-C 3 N 4 , which can stably localize at the water/toluene biphasic interface. This unique feature enables the formation of a quasi-Pickering emulsion under continuous stirring during the photocatalytic process, facilitating the simultaneous production and in situ separation of H 2 O 2 in the aqueous phase and benzaldehyde in the organic phase. The S-scheme heterojunction enhances visible-light absorption, promotes efficient electron-hole separation, and preserves the strong redox potential of photogenerated charge carriers. Under simulated sunlight, the optimized BOB/PCN-A photocatalyst achieves remarkable production rates of 2.29 mmol g −1 h −1 for benzaldehyde and 1.77 mmol g −1 h −1 for H 2 O 2 , with a 100 % selectivity toward benzaldehyde. This study showcases a green photocatalytic system that integrates synthesis and separation processes, offering promising implications for sustainable solar-driven chemical manufacturing.