Novel Z-Scheme/Type-II ZnO/Bi2MoO6/AgFeO2 Ternary Heterojunctions for Persulfate-Assisted Photocatalytic Elimination of Several Dyes Exposure to Visible Light

Abstract

Photocatalysis serves as an effective and environmentally friendly approach for the treatment of wastewater and water, with ZnO-based photocatalysts exhibiting significant efficacy in this area. Consequently, we present a novel method that integrates solvothermal, calcination, and hydrothermal processes to produce a ZnO/Bi₂MoO₆/AgFeO₂ ternary photocatalyst, which has shown a remarkable photocatalytic activity in eliminating methyl orange (MO), rhodamine B (RhB), and methylene blue (MB) when exposed to persulfate (SO₅²⁻) under visible light. The ZnO/Bi₂MoO₆/AgFeO₂ photocatalysts facilitate the activation of SO₅²⁻ ions, thereby enhancing the degradation of pollutants under visible light exposure. In the presence of the ZnO/Bi₂MoO₆/AgFeO₂ (20%)/SO₅²⁻ system, MB was entirely decomposed within 75 min, whereas only 39.8% of MB was eliminated using the ZnO/Bi₂MoO₆/AgFeO₂ (20%) sample without SO₅²⁻. This indicates a synergistic effect between SO₅²⁻ activation and visible-light photocatalysis in the ZnO/Bi₂MoO₆/AgFeO₂ (20%) system. The enhanced photocatalytic performance of this system is attributed to the activation of SO5²⁻ ions by electrons, leading to the generation of sulfate radicals (^⦁SO₄⁻), improved charge carrier separation, and increased visible light absorption by Bi₂MoO₆ and AgFeO₂. Ultimately, the proposed mechanism for the significantly enhanced photocatalytic activities involves multiple Z-scheme/type II heterojunctions. The findings of this study confirm that the ZnO/Bi₂MoO₆/AgFeO₂ system is a viable visible-light-driven nanocomposite for the purification of water and wastewater.