Tuning nanostructured CuCo2O4 on 3D macro-support for enhanced degradation of carbofuran via catalytic activation monopersulfate: Key roles of morphology and active species

Abstract

While a few OH-based oxidation technologies have been used for eliminating the highly toxic pesticide Carbofuran (CFR), very few studies have ever assessed SO4−-based oxidation technologies for degrading CFR. Even though monopersulfate (MPS) is increasingly used for producing SO4− and cobalt (Co) is the most useful element for activating MPS, almost no study has ever been implemented to evaluate cobaltic catalysts for activating MPS to degrade CFR. Thus, the goal of this study is to develop Co-based catalysts for activating MPS to degrade CFR. In particular, a hierarchic composite which is fabricated based on macroscale Cu foam (CF) with the decoration of nanoscale Co-based oxide is fabricated to combine the macroscale practicability, and nanoscale functionality of Co-based oxide. The modification of CF with Co would grow CuCo2O4 directly on CF, leading to the formation of CuCo2O4@CF (CCO@CF). Moreover, different cobalt salts and dosages of urea might alter the formation of CuCo2O4, leading to various morphologies and nanostructures, such as CCO@CF with filament (CCF), CCOF@CF with thorn (CCT), and CCOF@CF with sheet (CCS). Interestingly, CCS exhibited the faster interfacial reaction rate, lower charge transfer resistance, and more abundant Co2+ sites, and oxygen vacancy, enabling CCS to show the highest catalytic activity for MPS activation to degrade CFR among these three CCO@CFs. CCS also exhibits a much lower Ea of CFR degradation than CCF, CCT, and CuOF, revealing its advantage over other catalysts. Moreover, the degradation mechanism of CFR by CCO@CF-activated MPS has been also elucidated using the tests of radical probes, and electron paramagnetic resonance for identifying contributions of OH, SO4−, and 1O2 to CFR degradation. These results validate that CCO@CFs are useful heterogeneous catalysts for MPS activation, and especially, CCS appears as the most favorable CCO@CF to eliminate the toxic CFR.