Enhanced tetracycline degradation by N C codoped Fe2O3 with rich oxygen vacancies in peroxymonosulfate assisting photoelectrochemical oxidation system: performance, mechanism and degradation pathway

In this work, a cost-effective and eco-friendly N and C co-doped Fe2O3 (NC-Fe2O3) was fabricated using rose petals as biotemplate and in-situ doping sources of nonmetal doping agents (N and C) and used in peroxymonosulfate (PMS) assisting visible-light photoelectrochemical oxidation (Photo/catalyst/EC/PMS) system for tetracycline (TC) degradation. Benefiting from morphology duplication from rose petals, N and C co-doping and the resulted rich oxygen vacancies and Fe2+, the optimum NC-Fe2O3 (II) exhibited the largely enhanced TC degradation efficiency as compared to bare Fe2O3 prepared without rose petals biotemplates. 100 % of TC can be removed in 10 min in Photo/NC-Fe2O3 (II)/EC/PMS system, being 6.3 folds of bare Fe2O3. In addition, NC-Fe2O3(II) displayed good recyclability, universal adaptability for other organics removal, a wide range of pH adaptation, and strong anti-interference ability toward ions in real water. Chemical trapping experiments, electron paramagnetic resonance results and open-circuit potential analysis confirmed that hydroxyl radical (•OH) and electron transfer dominated the TC degradation in system. Moreover, TC degradation pathways were deduced based on the confirmed degradation products and density functional theory (DFT) calculation. This study opens up new prospects for designing efficient catalysts and makes Fe2O3 a potential candidate catalyst for organics removal.