Constructed anionic and cation vacancies in Mn3O4 for enhancing styrene complete oxidation: Unraveling the positive role of dual defects

Previous studies have primarily focused on the role of single defects, particularly oxygen vacancies, in the catalytic oxidation of volatile organic compounds (VOCs). However, the mechanisms by which coexisting defects influence catalytic activity remain unclear. In this work, dual manganese and oxygen vacancies were introduced in Mn 3 O 4 via solvothermal synthesis and low-temperature H 2 treatment, and a comprehensive analysis of catalysts with varying defect configurations was performed. The introduction of dual vacancies in V Mn -100-1 resulted in a reduced MnO 4 /MnO 6 ratio, leading to significant structural modifications. These changes enhanced the redox properties and promoted the migration of oxygen species. Consequently, V Mn -100-1 exhibited superior catalytic performance, stability, and moisture resistance (15%) for the complete oxidation of styrene. Additionally, designed experiments and density functional theory (DFT) calculations revealed that the dual vacancies improved oxygen species mobility and O 2 dissociation, while the co-existing defects and surplus O 2 mitigated the adverse effects of moisture. In situ diffuse reflectance infrared spectroscopy and DFT results indicated that the dual vacancies enhanced styrene activation and maleic anhydride decomposition. Thus, the rate-limiting steps were modified and the reaction process was optimized. This study provides new insights into dual-defect systems and offers a novel approach for designing high-efficiency catalysts for VOC degradation.