Hetero-interface-engineered sulfur vacancy and oxygen doping in hollow Co₉S₈/Fe₇S₈ nanospheres towards monopersulfate activation for boosting intrinsic electron transfer in paracetamol degradation

Abstract

Designing defects-rich hollow heterostructure bimetal sulfides is considered as an efficient strategy for accel-erated monopersulfate (MPS) activation. Herein, mono-step sulfidation was employed to develop sulfur vacancy (SV)-rich hollow oxygen-doped Co9S8/Fe7S8 (O-CSFS). SV and oxygen doping-induced highly electroactive sites, low charge resistance, and increased conductivity of O-CSFS accounted for its superior performance. Reactive oxygen species (ROS)-driven pathway and electron transfer (ET)-driven pathway were revealed to be responsible for PCM degradation in O-CSFS/MPS system, but the role of ET-driven pathway was more significant. The ROS-driven pathway was mainly attributed to electrons-rich low valance of Co atoms which activated MPS to generate different ROS without (OH)-O-center dot contribution and with a greater role of SO4 center dot- than O-1(2). Doped O, S species, and surface-active O-CSFS/MPS complex in ET-driven pathway, meanwhile, acquired electrons from PCM, resulting in enhanced PCM oxidation. This study provided more insight into ET-enhanced efficient PCM degradation induced by SV and oxygen-doping.