Structural Design and Photocatalytic Performance Study of Binary and Ternary Photocatalysts Based on ZnO , TiO 2 , and SiO 2 Oxides for Azo Dye Degradation

ABSTRACT Semiconductor photocatalysis offers a promising approach for degradation of organic dye contaminants from industrial effluent; however, rapid charge‐carrier recombination and limited optical absorption in single‐component photocatalysts often reduce degradation efficiency. To overcome these limitations, this study focuses on developing binary and ternary oxide composites with tailored structures and optimized compositions to enhance UV‐assisted photocatalysis. The metal oxides were synthesized in ZnO/TiO 2 , TiO 2 /SiO 2 , ZnO/SiO 2 , and ZnO/TiO 2 /SiO 2 combinations by using a sol–gel method. The prepared metal oxide composites were characterized for band‐gap energy, morphology, and structural properties and then used to degrade MB and MO dyes in solution. The photocatalytic degradation experiments were performed under UV irradiation using a 36 W discharge lamp with an emission wavelength range of 300–400 nm. Comparative photocatalytic experiments were conducted using an initial dye concentration of 10 mg/L, a catalyst loading of 5.0 g/L, a reaction time of 180 min, and a solution pH of 6.5. The ZnO/TiO 2 showed 98.44% and 97.69% removal efficiency against MB and MO dyes, respectively. The high degradation efficiency is possibly due to improved charge separation, a low electron–hole recombination rate, and an extended lifetime of the electrons within the photocatalyst structure.