Construction of carboxyl position-controlled Z-scheme n-ZnO/p-Cu2O heterojunctions with enhanced photocatalytic property for different pollutants

High reaction activity, strong redox capability, stable Z-scheme transfer and good photostability may benefit the enhancement of photocatalytic performance of n-p heterojunction. Herein, novel 1,2-, 1,3- and 1,4-benzene dicarboxylic acids (1,2-BDCA, 1,3-BDCA and 1,4-BDCA) were used to tune carboxyl positions during the hydrothermal formation process of ZnO nanostructures, and then Z-scheme n-p heterojunctions were constructed via anchoring Cu2O nanoparticles on ZnO surface. When 1,2-BDCA molecule is added into reaction solution, the synergistic capping effect of its two - COOH groups on ZnO surface becomes strong, and leads to the formation of many ZnO nanosheets and well-contacted interface between ZnO and Cu2O. When four pollutants are photodegraded, ZnO-Cu2O (S1-Cu2O) heterojunction prepared by 1,2-BDCA possesses higher charge separation efficiency, stronger redox potentials, and stabler Z-scheme charge transfer. Due to these advantages, S1-Cu2O heterojunction exhibits higher reaction activity and better photocatalytic performance than those of ZnO, Cu2O, TiO2-P25 and/or commercial ZnO (CZnO) under irradiation of ultraviolet and visible light. In addition, the ZnOCu2O heterojunction exhibits excellent photostability and recyclability for photodegradation of pollutants. Therefore, this study reports a novel strategy to control the Z-scheme charge transfer, and the as-prepared ZnOCu2O photocatalysts provide a perspective for the application in environmental purification and remediation.