In-situ Ni and F co-doped sulfur vacancies rich photoresponsive AgIn5S8 mediated peroxymonosulfate activation for elimination of sulfamethoxazole in water

Abstract

The present study reporting the construction of Ni and F co-doped AgIn₅S₈ (AIS) via facile hydrothermal strategy, engineered for superior photocatalytic degradation of sulfamethoxazole (SLX). SEM analysis revealed mesoporous micro spherical morphology of AIS, while EDAX analysis validated the successful incorporation of Ni and F dopants. XRD analysis identified the cubic spinel phase of AIS with well-defined hkl planes, while the emergence of composite peaks elucidated integration of Ni and F within the crystal lattice. BET and BJH analyses demonstrated a substantial increase in surface area, enhancing adsorption and photocatalytic performance. XPS and PL studies further confirmed the presence of doping-induced sulfur defects, effectively improving charge separation efficiency and minimizing electron-hole recombination. The optimized Ni/F-AIS catalyst and peroxumonosulfate activation exhibited 92.07 % mineralization of SLX with a rate constant of 0.0042 min⁻¹, which is 1.75 times higher than pristine AIS. The mechanistic insights gained through radical scavenging assays and ESR analysis confirmed the dominant role of O₂•⁻ radicals in the degradation process. A remarkable reusability efficiency of 89.75 % after six successive cycles underscores the long-term stability and durability of the photocatalyst. UV–vis DRS studies provided deeper insights into charge transfer mechanisms, revealing the Burstein-Moss effect, which modulates the optical bandgap and enhances visible-light absorption. Furthermore, mineralization pathway was systematically elucidated through GC-MS analysis, and the toxicity of degradation intermediates was assessed via ECOSAR tool, ensuring environmental compatibility. These findings pave the way for advanced wastewater treatment technologies and the effective removal of emerging pharmaceutical contaminants.