Enhanced and synergistic catalytic activation through spinel-carbon built-in electric field: A novel pathway for generating1O2

The removal of emerging micropollutants in complex water matrices usually requires excessive oxidants and/or energy input, resulting in low cost-effectiveness and potentially causing secondary pollution. Therefore, achieving selective oxidation of target micropollutants for water purification is meaningful but challenging. Herein, a built-in electric field (BIEF) from MnFe₂O₄ nanosheet arrays to carbon cloth (CC) substance is constructed, in which the electrons transfer from Mn and Fe atoms to neighboring C atoms, resulting in a positive shift of the d band of Mn and Fe sites and the increase of electron density at Fermi level. With the influence of the BIEF, the activation of peroxymonosulfate (PMS) by MnFe₂O₄ is nearly 100 % redirected towards nonradical pathways. Furthermore, DFT calculations reveal a significant enhancement in PMS adsorption, which leads to a decrease in the energy barrier required for the direct generation of ${{}^1\mathrm{O}}_2$${{}^1\mathrm{O}}_2$ from PMS*, opening a new pathway from PMS*$\to {{}^1\mathrm{O}}_2$$\to {{}^1\mathrm{O}}_2$. The fabricated Fenton-like oxidation system delivers selective oxidation towards electron-rich organic micropollutants. This study deepens the understanding of the driving force behind the activation of PMS by BIEF and provides new insights into the design of innovative spinel-carbon catalysts.