Selective photocatalytic hydrogen peroxide production in pure water through interfacial charge-flow engineering and oxygen adsorption control in an S-scheme Mn0.2Cd0.8S/ZnIn2S4 heterojunction

Photocatalytic hydrogen peroxide (H 2 O 2 ) synthesis in pure water (H 2 O) is challenging because it requires simultaneous efficient charge separation and selective two-electron oxygen reduction. Herein, we report an S-scheme Mn 0.2 Cd 0.8 S/ZnIn 2 S 4 (MZ) heterojunction that synergistically regulates interfacial charge flow and surface oxygen (O 2 ) adsorption configuration. The optimized MZ-15 achieves a H 2 O 2 production rate of 3917.3 μmol g −1  h −1 in pure water without sacrificial agents. The S-scheme pathway promotes charge separation while preserving strong redox capability. More importantly, the pronounced ionic-radius mismatch between Mn 2+ and Cd 2+ in Mn 0.2 Cd 0.8 S induces an asymmetric electronic environment that shifts O 2 adsorption from side-on to end-on (Pauling-type) configuration, thereby favoring O O bond retention and two-electron oxygen reduction reaction (2e − ORR). This work highlights that simultaneous engineering of interfacial charge dynamics and O 2 adsorption geometry is a powerful strategy for highly selective photocatalytic H 2 O 2 production An S-scheme Mn 0.2 Cd 0.8 S/ZnIn 2 S 4 heterojunction achieves coupled interfacial charge-flow engineering and Pauling-type O 2 adsorption to realize selective 2e⁻ ORR for H 2 O 2 production in sacrificial‑agent‑free pure water. Download: Download high-res image (187KB) Download: Download full-size image