Activation of peroxymonosulfate by NiCo2S4/covalent organic framework composites for the degradation of organic pollutants: Catalytic performance and mechanism

Abstract

The peroxymonosulfate (PMS)-based advanced oxidation process has attracted considerable interest in the degradation of refractory pollutants owing to the potent oxidative ability and outstanding degradation performance. However, the development of high-performance catalysts remains a key challenge for achieving efficient PMS activation. In this work, polyimide-based covalent organic framework (PI-COF) is designed to support cobalt spinel oxides (NiCo₂S₄) for activating PMS in the efficient degradation of organic pollutants. The NiCo₂S₄/COFs composites show high catalytic activity due to the redox processes of Ni³⁺/Ni²⁺, Co³⁺/Co²⁺, S²⁻/S₂²⁻/S⁰/S_n²⁻/SO₄²⁻ and the electron transfer of sulfur vacancies (SVs) induced by the introduction of NiCo₂S₄ on PI-COF. The NiCo₂S₄/COFs composites also possess good applicability for diverse antibiotics and dyes and robust stability over 7 cycles. The activation mechanism study manifests that ¹O₂, $O_2^{·‐}$ and ${\mathrm{SO}}_4^{·‐}$ are the leading reactive oxygen species (ROS). The probable degradation pathway is concluded via identifying intermediate compounds, and computational toxicity evaluation demonstrates the lower ecotoxicity of intermediates. This work presents a novel strategy for degrading aqueous organic pollutants through PMS activation.