Interfacial microenvironment engineering of cadmium sulfide by carbon dots towards efficient photocatalytic hydrogen...

Hydrogen peroxide (H₂O₂) is an indispensable green oxidant and chemical feedstock. Photocatalytic synthesis of H₂O₂ presents a sustainable alternative paradigm to the energy-intensive anthraquinone process due to its low energy consumption and zero pollutant generation. While cadmium sulfide (CdS) is a promising photocatalyst for H₂O₂ generation via the two-electron oxygen reduction reaction (ORR), its practical application is plagued by the inherent trade-off between activity and stability, resulting from weak oxygen adsorption and severe photocorrosion. Herein, we demonstrate that interfacial microenvironment engineering of CdS by Carbon dots (CDs) can enable efficient photocatalytic H₂O₂ production by modulating surface O₂ adsorption. Molecular dynamics (MD) simulations show that CDs enrich the concentration of reactant O₂ by 4 times compared to the bare CdS surface, creating a favorable interfacial microenvironment for ORR. Consequently, the optimal CDs/CdS photocatalyst delivers an outstanding H₂O₂ production rate of 2.21 mmol g^-1 h^-1 and remarkable recyclability, sustaining stable performance over 13 consecutive cycles (cumulative reaction time > 50 h) under visible-light irradiation at ambient conditions, outperforming previously reported CdS-based systems. More importantly, the in-situ generated H₂O₂ by CDs/CdS photocatalysts demonstrates high practical utility, rapidly degrading over 99.5% of methylene blue (MB) within only 1 min via the Fenton reaction and effectively disinfecting the Escherichia coli (E. coli). This work provides a novel design principle of interface microenvironment engineering for developing high-performance photocatalytic systems.