Regulating the covalency of Co-O bond by Fe incorporation achieves efficient peracetic acid activation for durable water purification

Advanced oxidation processes (AOPs) relying on peracetic acid (PAA) have drawn extensive attention due to their environmental benignity. Enhancing the activation of PAA and the creation of organic radicals (RO•) are of great significance for decontamination. Regulating the covalency of the metal-oxygen bond can break the limitation of PAA activation and improve the generation of radicals. Herein, CuCo_0.6Fe_0.4O₂ with a high covalency of Co-O bond is developed by Fe incorporation in CuCoO₂. The CuCo_0.6Fe_0.4O₂/PAA system exhibits superior catalytic performance for 2,4,6-TCP degradation (97.2 %), and the corresponding k_obs (0.171 min⁻¹) is 17 times higher than that of the CuCoO₂/PAA system. The introduction of Fe triggers electron rearrangement, increasing the proportion of Co(II) on the catalyst's surface. The substitution of Fe enhanced the adsorption of PAA (ΔE_ads = −6.98 eV), decreasing the electron-transfer resistance, promoting the activation of PAA with Co(II) acting as an electron donor, thus accelerating the formation of CH₃C(O)OO• and the degradation of pollutants. In addition, the Cu(I) site can supply electrons to the Co site, promoting the efficient reduction of Co(III), breaking the contradiction between the active site and PAA redox relationship, thus ensuring the sustainable performance of CuCo_0.6Fe_0.4O₂. The removal % of 2,4,6-TCP is up to 91.3 % during long-lasting running of the continuous reaction process, validating the practical application potential of the CuCo_0.6Fe_0.4O₂/PAA system. This work provided novel insights into precisely regulating the covalency of transition metal oxides to achieve efficient removal of pollutants.