Tuning Electron Localization to Unlock Inert Tetrahedral Oxygen Species for Boosting Catalytic Oxidation of VOCs from...

Aromatic hydrocarbons (e.g., toluene) and oxygenated volatile organic compounds (VOCs) (e.g., acetone) usually exist in typical industrial environments. Although catalytic oxidation is promising for their simultaneous removal, competitive adsorption and the selective reactivity of oxygen species limit its synergistic efficiency. Herein, Lanthanum (La) was introduced to modulate the electron localization at tetrahedral (Td) and octahedral (Oh) sites in CoMn₂O₄, thereby governing the distribution and reactivity of oxygen species, accompanied by an overall shift in surface acid-base properties. The large ionic radius and low electronegativity of La³⁺ induce pronounced lattice distortion and charge redistribution, particularly in tetrahedral sites of La_0.1Co catalyst, activating otherwise inert Co_Td-O units for efficient O₂ activation and rapid replenishment of oxygen vacancies under high temperature conditions. Simultaneously, La doping weakens Mn_Oh-O bonds at octahedral sites and stabilizes Mn⁴⁺ to enhance lattice oxygen mobility and reactivity. This dual activation enhances electrophilic attack on aromatic rings and promotes C-H bond activation, governing the oxidation of toluene and acetone. The overall optimization of surface acid-base properties mitigates competitive adsorption and facilitates the degradation of reaction intermediates. Notably, for mixed VOCs removal, La_0.1Co lowers the T₉₀ for toluene by 45 °C and increases the specific reaction rate of toluene oxidation compared to pristine CoMn₂O₄. This work provides insights and modification strategies for designing efficient catalysts tailored to both single- and mixed-component VOCs.