Engineering oxygen vacancies in acid-etched MgMn₂O₄ for efficiently catalytic benzene combustion: Synergistic activation of gaseous oxygen and surface lattice oxygen

The synergistic activation of gaseous oxygen and surface lattice oxygen is essential for designing highly efficient catalysts to eliminate VOCs. Herein, an effective acid treatment was carried out to create more oxygen vacancies by modulating the electronic structure of MgMn₂O₄ spinels and MgMnO_x mixed oxides. The acid-treated MgMn₂O₄ exhibited outstanding catalytic performance, with the reaction rate of benzene rising by 8.55 times at 200 °C. After acid treatment, MgMn₂O₄ partially retained its spinel structure, while Mn₂O₃ in situ grew on the surface due to the selective removal of Mg²⁺. The transformation of Mn-O-Mg into Mn-O weakened the strength of adjacent Mn-O bonds, thereby promoting the release of surface lattice oxygen and the regeneration of oxygen vacancies. In addition, acid-treated MgMn₂O₄ facilitated the adsorption and activation of gaseous oxygen. In situ DRIFTS analysis proved that the synergistic activation of gaseous oxygen and surface lattice oxygen accelerated the conversion of intermediates, thus contributing to the efficient degradation of benzene.