Construction of step-scheme g-C3N4/Co/ZnO heterojunction photocatalyst for aerobic photocatalytic degradation of synthetic wastewater

In this paper, ternary g-C3N4/Co/ZnO heterojunction photocatalyst has been reported for dye degradation. The simple ultrasonic and sol-gel method is used to synthesize g-C3N4/Co/ZnO nanocomposite and the physico-chemical characteristics are used to determine the phase structure, particle size, morphology, surface area, size distribution, elemental analysis, electronic structure, energy potential positions, and separation and transfer efficiency of photogenerated electron-holes. The data indicate that an intimate stable and efficient heterojunction is established. The aerobic photocatalytic efficiency of the step scheme (S-scheme) g-C3N4/Co/ZnO photocatalyst was evaluated using methylene blue (MB), crystal violet (CV), and Rhodamine B (RhB) cationic dyes as model pollutants under visible light irradiation. Degradation removal of 96.3%, 74.5%, and 75.14% was observed for MB, CV, and RhB dyes, respectively. In order to compare the degradation efficiency under different light irra-diations, RhB was irradiated under visible and sunlight and the degradation efficiency increased to 91.6% under sunlight. The surface plasmon resonance (SPR) effect of metallic Cobalt (Co) nanoparticles in this S-scheme hybrid photocatalyst facilitates vectorial interfacial electron transport and enhances the response of the photocatalyst to sunlight. As a result, the optimized S-scheme g-C3N4/Co/ZnO photocatalyst was employed to treat the complex wastewater and degraded up to 91.26% within 120 min under sunlight. The superior pho-tocatalysis behavior and its recyclability make it a promising photocatalyst for several environmental applications.