Synergizing Hydrophilicity and S-Scheme Heterojunction for Efficient Photocatalytic H ₂ O ₂ Production from Pure Water

Against the backdrop of escalating ecological and energy crises, producing hydrogen peroxide (H 2 O 2 ) from water photocatalytically has attracted significant attention as a sustainable solution. COFs are promising photocatalysts for H 2 O 2 synthesis because of their tunable porous structures and high surface areas. However, the practical application of COFs is limited by rapid charge-carrier recombination and poor hydrophilicity. Here, an S-scheme heterojunction was constructed by in situ growing In 2 S 3 on a COF substrate. The incorporation of In 2 S 3 enhanced the light absorption and hydrophilicity of COF and accelerated the charge separation and transport. The synergy of hydrophilicity and an S-scheme heterojunction in In 2 S 3 @COF-30 contributed to the improved photocatalytic H 2 O 2 production rate (1101.85 μmol g –1 h –1 ) in pure water without sacrificial agents. This work presents a strategy for designing hydrophilic S-scheme heterostructures to overcome the limitations of COF-based photocatalysts and advances sustainable, solar-driven H 2 O 2 production.