Highly Efficient Photocatalytic H2O2 Production over a Zn0.3Cd0.7S/MXene Photocatalyst for Degradation of Emerging Pollutants under Visible-Light Irradiation

Hydrogen peroxide (H₂O₂) is an ideal green product with a broad range of applications, and visible-light-driven photocatalytic H₂O₂ production is deemed a sustainable and eco-friendly strategy. Herein, various Zn_xCd_1-xS/MXene photocatalysts with a Schottky junction were prepared for photocatalytic H₂O₂ production. The obtained Zn_0.3Cd_0.7S/MXene (ZCM-0.3) hybrid presented the highest photocatalytic H₂O₂ production rate in pure neutral water of 1160 μmol h^-1 g^-1, which was further improved to 2178.58 μmol h^-1 g^-1 in the presence of isopropanol as the sacrificial reagent. The experimental results demonstrated that the sufficient visible-light-harvesting ability and appropriate conduction band potential of the Zn_0.3Cd_0.7S solid solution, the excellent conductivity and two-electron selectivity of MXene, and the construction of Schottky junctions at the Zn_0.3Cd_0.7S/MXene interface resulted in the fast transfer and separation of the photogenerated charge carriers and the targeted reduction of oxygen to H₂O₂. The photocatalytic mechanism for H₂O₂ production was studied and proposed. Moreover, a simple photo-Fenton system consisting of Zn_xCd_1-xS/MXene and ferrous ions (Fe²⁺) was constructed and applied for the degradation of various emerging pollutants, which also performed effectively and exhibited universality across different pollutants. Overall, this study presents a novel and useful strategy to convert solar energy into chemical energy through efficient H₂O₂ production and provides an effective alternative for the degradation of emerging pollutants.