Interfacial Proton Regulation in an S-Scheme Pt-CQD/K ₃ PW ₁₂ O ₄₀ Heterojunction Boosts Selective H ₂ O ₂ Synthesis during Overall Water Splitting

Solar-driven overall water splitting offers a sustainable route for producing hydrogen and hydrogen peroxide, yet achieving high H 2 O 2 selectivity remains challenging due to competing proton-coupled electron transfer pathways. Here we construct an S-scheme heterojunction composed of carbon quantum dots (CQDs) and K 3 PW 12 O 40, where the built-in electric field at the interface enhances charge separation and promotes proton transfer, creating a favorable microenvironment for selective H 2 O 2 generation. This catalyst achieves H 2 and H 2 O 2 production rates of 603 and 586 μmol/g·h simultaneously under visible light irradiation. The tailored electronic structure lowers energy barriers for key intermediates, facilitating selective H 2 O 2 production. These findings demonstrate that interfacial proton regulation combined with broad light absorption and efficient charge separation can guide the design of multifunctional photocatalysts for scalable solar-driven H 2 O 2 synthesis.