Interface-engineered In₂S₃/polydopamine S-scheme heterojunction for enhanced solar-driven H₂O₂ generation

Photocatalytic H₂O₂ production offers a sustainable alternative to energy-intensive routes; however, a random heterointerface and poor visible-light response of the photocatalyst restrict its activity. Herein, a distinct organic-inorganic S-scheme heterojunction was rationally designed by coating polydopamine onto In₂S₃ (denoted as 3PIS), exhibiting a defined interfacial area and extending visible-light absorption, leading to enhanced H₂O₂ evolution (89.6 μmol g⁻¹ min⁻¹; 5-fold higher than pristine In₂S₃) in pure water without sacrificial agents. The 3PIS architecture enables prolonged carrier lifetime, facilitates charge accumulation, and electron delivery to activate molecular oxygen via a two-electron oxygen reduction reaction. The reduced thermodynamic barriers enable the formation of critical *OOH intermediates, which undergo subsequent protonation and reduction to generate H₂O₂. In addition, the photogenerated H₂O₂ achieves 100% bacterial inactivation, further reflecting the stable and selective H₂O₂ production over 3PIS. This study furnishes a potentially extendable design of organic-inorganic heterojunctions toward sustainable solar-to-chemical energy conversion.

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