Electron structure modulation and bicarbonate surrounding enhance Fenton-like reactions performance of Co-Co PBA

Although several strategies have been developed to improve the efficiency of heterogeneous Fenton-like reactions, investigating the relationship among the electronic properties of the catalyst surface, the complex water matrix and catalytic activity remains challenges. Herein, the electron density of the active site Co(II) in Co Prussian blue analogs (Co-PBAs) is proved to be modulated by the anion source method. The elevated electron density of Co(II) and the higher metallicity of the catalyst lead to an increase in electron transport efficiency as revealed by X-ray photoelectron spectra (XPS), Fourier transform infrared spectroscopy (FT-IR), and density functional theory (DFT) calculations. Furthermore, the negative shift of the D-band center of Co(II) can effectively release intermediates to avoid catalyst poisoning. Bicarbonate has been demonstrated to activate peroxymonosulfate (PMS) by weakening the peroxide bond. Its activation mechanism involves free radical mechanism and non-radical mechanism: the first step is the generation of HCO₄^-, then it is further hydrolyzed to generate •OH and ¹O₂, and the other is HCO₄^- interact with Co(III) to form Co(IV)=O. In addition, the degradation pathways of target contaminants p-nitrophenol and toxicity verification of intermediate products have been investigated. This study provides guidance for the research of Fenton-like reactions.