S-scheme heterojunction based on CuWO4/WO3 microspheres with an improved photocatalytic property under visible light irradiation

Abstract

Dye wastewater green treatment has always been one of the research hotspots in the environmental protection and remediation field. The photocatalytic degradation and mineralization of organic dyes are considered to be an energy conservation and effective wastewater remediation technology. Novel CuWO₄/WO₃ S-scheme nano-heterojunction microspheres were prepared through a convenient hydrothermal route and impregnation–calcination method. The structure, composition, electrochemistry and optical properties of the nano-heterojunction microspheres were systematically evaluated via XRD, SEM, TEM, electrochemical analysis and spectrometry, and the photocatalytic activity of CuWO₄/WO₃ was investigated using methylene blue (MB) as the probe under visible light irradiation. The CuWO₄/WO₃ S-scheme nano-heterojunction exhibited a boosted photocatalytic activity compared with WO₃ owing to a decrease in carrier transfer resistance and an increase in carrier separation efficiency. The MB degradation rate of the CuWO₄/WO₃-10 S-scheme nano-heterojunction microspheres is 1.83 and 3.10 times higher than that of pure WO₃·2H₂O and WO₃ microspheres, respectively. Based on the active species capture experiments and the Mott–Schottky curve, an S-scheme mechanism of the photogenerated carrier transfer was elucidated. This study reveals a design and method for the synthesis of S-scheme nano-heterojunction catalysts for application in the wastewater purification field.