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.

GRAPHICAL ABSTRACT

Keywords:

• AgIO₄/TiO₂ nanocomposites
• visible light-driven photocatalyst
• AgIO₄ mesoporous structure
• direct Z-scheme mechanism
• RhB dye