Enhanced peroxymonosulfate activation by CoFe doped carbon polyhedral nanocages through protecting-etching regulation for ciprofloxacin degradation

Improving the activation efficiency of peroxymonosulfate (PMS) to produce more radicals is crucial to promote Fenton-like reactions. Herein, hollow carbon polyhedral nanocages-loaded CoFe catalysts via tannic acid etching (TA-CoFe-NC) were prepared based on the metal-ligand exchange mechanism. The magnetic catalyst, with little metal leaching during reaction, achieved the removal efficiency of 95.5 % in ciprofloxacin degradation within 30 min and a first-order kinetic constant of 0.054 min −1 under optimal conditions (0.1 g·L −1 catalyst, 0.2 g·L −1 PMS, unadjusted pH), a 10.76-fold enhancement compared to the unetched catalyst. By quenching experiments and EPR, 1 O 2 , SO 4 •− , and • OH were proved to be the critical reactive species in degradation process. Density functional theory calculations elucidated the adsorption of PMS and the spontaneous decomposition into • OH and SO 4 •− in catalytic process. High d-band center and low integrated crystal orbital Hamilton population promoted the charge transport and catalytic property. Degradation pathway and toxicity of intermediates were also investigated, and exhibited excellent stability and tolerance to environmental interferences. The rational protecting-etching manipulation by TA helps design novel catalysts with high performance and stability, and facilitates PMS adsorption and interfacial electron transfer to achieve the synergetic stabilization-promotion effect.