Microwave assisted facile fabrication of dual Z-scheme g-C₃N₄/ZnFe₂O₄/Bi₂S₃ photocatalyst for peroxymonosulphate mediated degradation of 2,4,6-Trichlorophenol: The mechanistic insights

Abstract

A ternary dual Z-scheme composite gCN/ZnFe₂O₄/Bi₂S₃ (ZFO/BS) was synthesized via a facile microwave assisted process and its photocatalytic potential was explored towards visible light driven removal of 2,4,6-tricholorophenol (TCP) with subsequent peroxymonosulfate (PMS) activation. Surface-bound Fe^2+3/|_surf.,Zn^+/2+|_surf.and Bi^3+/4+|_surf. were effective towards charge carrier channelization and evolution of reactive species. Highest catalytic activity was experienced for the catalyst with 10 wt% Bi₂S₃ (ZFO/BS(10)) and 98.9% TCP was removed with 0.25 gL^-1 catalyst and 1.0 gL^-1 PMS, under 60 mins visible light irradiation (intensity: 80 W). Construction of dual Z-scheme heterojunction was studied using XPS and the mechanism of e^-/h⁺ separation was elucidated. In-depth radical scavenging and EPR analysis confirmed the coexistence and relative contributions of various reactive radicals towards degradation. Plausible TCP degradation pathway was designed based on intermediate analysis. This study elucidates the superiority of dual Z-scheme ternary heterojunction towards separation of photogenerated charge carriers and mineralization of various emerging contaminants.