Co-Cu-Al-Ox for chloramphenicol degradation: Modification of CoOx coordination and electronic environment by Cu incorporation

Abstract

In heterogeneous Fenton catalysis, the modification of electronic structures at active sites is crucial for enhancing degradation efficiency. This strategy enhances the activation of H₂O₂ and the subsequent generation of hydroxyl radicals (·OH). However, the effectiveness of these processes is often limited by suboptimal coordination environments at the active sites. In this study, we synthesized a series of MAl₂O₄ (M=Co and/or Cu) catalysts with spinel structures, specifically tailored for the efficient degradation of chloramphenicol (CAP). We modulated the electronic structure at the active sites by strategically incorporating Cu atoms, controlling the doping concentration to boost the surface enrichment of Cu-embedded CoO₆ on CoAl₂O₄, thus optimizing catalyst performance. This alteration promotes Cu–O-Co interactions within the MO₆ environment, enhancing the reducibility of Cu atoms and boosting electron donation and transfer during reactions. This improvement leads to more effective adsorption of H₂O₂ and enhanced desorption of hydroxyl radicals, coupled with improved regeneration of active sites. The optimized Co_7.5Cu_2.5/Al₂O₃ catalyst achieved a remarkable 95.5 % conversion rate of chloramphenicol, demonstrating its potential as an effective solution for treating persistent organic pollutants.