Electronic structure modulation and peroxymonosulfate activation mechanism of N-doped MnCo2O4: A study on the efficient catalytic degradation of sulfamethoxazole

Abstract

In this study, a nitrogen-doped MnCo₂O₄ composite material (nN-MCO) was successfully synthesized via a urea-assisted thermal treatment method and applied for the activation of peroxymonosulfate (PMS) to degrade sulfamethoxazole (SMX). By introducing metal-N (M−N) bonds, the concentration of oxygen vacancies on the catalyst surface and its electron transfer capability with PMS were significantly enhanced. Experimental characterizations demonstrated that nitrogen doping not only strengthened the covalency of the metal-O (M−O) bonds but also facilitated the formation of electron-rich metal sites through electronic rearrangement, further improving the adsorption and activation of PMS. The 2 N-MCO catalyst successfully degraded 98.0 % of SMX within 5 min and maintained a removal efficiency of 85.0 % after four consecutive cycles. The study revealed that ¹O₂, SO₄⁻, OH and O₂⁻ were all involved in the degradation of SMX, with ¹O₂ identified as the dominant reactive oxygen species. This work presents a simple and effective nitrogen-doping strategy for surface modification of spinel-based catalysts, enhancing the MnCo₂O₄ composite’s electronic structure, strengthening metal–oxygen bonds, and creating electron-rich sites. These modifications promote oxygen vacancies, improve electron transfer, and enable efficient reactive oxygen species (ROS) generation, offering valuable insights and theoretical support for PMS-based oxidation processes in pollutant treatment.