Sol-gel synthesis of ternary CuO/TiO 2 /ZnO nanocomposites for enhanced photocatalytic performance under UV and visible light irradiation

Abstract

Abstract The present study investigates the photocatalytic degradation of methylene blue by sol-gel-synthesized ternary CuO/TiO2/ZnO nanocomposites with different CuO loadings. The resulting nanocomposites were characterized to determine their properties, such as their crystalline structure, morphology, band gap, and specific surface area using X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy, ultraviolet (UV)–visible diffuse reflectance spectroscopy, Brunauer–Emmett–Teller surface area analysis, electron spin resonance, and photoluminescence (PL) measurement. The photocatalytic performance of ternary CuO/TiO2/ZnO with a molar ratio of 0.5:1:1 exhibited the best photocatalytic activity under both UV and visible light irradiation with rate constants of approximately 0.045 and 0.025 min−1, respectively. The superior photocatalytic performance of ternary CuO/TiO2/ZnO was due its suppressed charge-carrier recombination and higher specific surface area. Under the optimum conditions, 100% and 98% of methylene blue were removed within 2 h under UV and visible light, respectively. In addition, three different scavengers were added into the solution to determine the main active species in the degradation process. The results showed that holes were the main active species in the degradation process.