Metal–Organic Framework-Derived Hollow CoMn₂O₄ Nanocube Catalysts for Deep Toluene Oxidation

Designing unique nanostructures and components for catalysts can promote the deep catalytic degradation of volatile organic compounds into CO2. Herein, a pyrolysis strategy for MOF-based oxides (Mn3[Co(CN)6]2·nH2O) was employed to successfully synthesize oxygen vacancy-enriched Mn–Co spinel oxides with hollow nanocube structures (denoted as MOF-CMO/400). Compared with CoMn2O4 nanoparticles prepared by the traditional precipitation method, MOF-CMO/400 presented a T90 of 209 °C for toluene catalytic oxidation, which was 38 °C lower than that of CoMn2O4 nanoparticles (247 °C). Especially in a high-temperature region, MOF-CMO/400 nanocubes possessed a narrower temperature range to achieve 100% toluene conversion than CoMn2O4 nanoparticles. The excellent catalytic activity of MOF-CMO/400 is mainly attributed to the three-dimensional hollow structure, more oxygen vacancy defects, longer Mn–O bonds, and abundant active oxygen species. Furthermore, MOF-CMO/400 nanocubes displayed good humidity resistance (above 5–10 vol % H2O). Therefore, the nanocatalyst with a distinctive structure and defects has great potential in industrial application for deep toluene oxidation.