Construction of direct Z-scheme AgIO4/TiO2 heterojunctions for exceptional photodegradation of rhodamine B dye

Abstract

The probably designed heterojunction is promising issue for destruction of organic pollutants in wastewater under sunlight energy. Herein, a novel AgIO4/TiO2 heterojunctions containing (5 wt%, 10 wt%, 15 wt%, and 20 wt%) AgIO4 were emerged for exceptional photocatalytic degradation of rhodamine B dye in short contact time adopting direct Z-scheme mechanism. Titania single phase was synthesized by sol-gel using Triton X-100; however, novel AgIO4 nanoparticles were incorporated on titania surface through sonochemical route. The as-synthesized nanocomposites were systematically characterized by x-ray powder diffraction, N2 adsorption–desorption isotherm, x-ray photoelectron spectroscopy, diffuse reflectance spectroscopy, photoluminescence (PL), energy-dispersive x-ray spectroscopy, mapping, and high-resolution transmission electron microscopy. Mass ratio of AgIO4 plays a pivotal role in light-harvesting absorption and enhancing the photocatalytic efficiency. Surprisingly, remarkable shifts in AgIO4 diffraction peaks, distortion in the nanostructure, and reduction in PL intensity of titania reveal the successful construction of AgIO4/TiO2 heterojunctions. The as-achieved AgIO4/TiO2 nanoparticles exhibit an excellent photoreactivity and stability toward degradation of RhB with optimal concentration 10 wt% AgIO4 for removal 98% of RhB dye on 0.3 g/L photocatalyst compared with 62% removal on bare TiO2 under the same reaction conditions. The exceptional reactivity of the heterojunction was ascribed to extending the light-harvesting and novel direct Z-scheme mechanism which not only improves the quantum power of charge carrier separation, but also enhances the oxidative and reductive efficiency of the photogenerated holes and electrons.