Quenching-treated β-MnO₂ Nanorods: Enhanced Catalytic Performance in Selective Oxidation of Cinnamyl Alcohol

In this research, β-MnO₂ nanorods enriched with surface oxygen vacancies were successfully fabricated through a facile quenching strategy using pristine β-MnO₂ nanorods as the precursor. The quenched samples were applied as the catalysts for the selective oxidation of cinnamyl alcohol to cinnamaldehyde. By varying the calcination temperature, the influence of surface structure of quenched β-MnO₂ nanorods on their catalytic performance was investigated.The results showed that the catalytic activities of quenched β-MnO₂ nanorods were significantly better than that of precursor and naturally cooled β-MnO₂ nanorods after calcination. Notably, the β-MnO₂ nanorods calcined at 350 ℃ followed by rapid cooling achieved the highest catalytic performance, with a cinnamyl alcohol conversion of 53.1% and a cinnamaldehyde selectivity of 95.2%, outperforming several commercial non-noble metal oxides. Various physicochemical characterizations demonstrated that the quenching technique could enhance the surface lattice oxygen activity and oxidation ability of β-MnO₂ nanorods, thereby effectively boosting their catalytic oxidation performance. This work demonstrates that quenching technique has a positive effect on increasing the surface oxygen vacancy concentration and catalytic performance of MnO₂, which offers an effective strategy for designing the high-efficiency non-noble metal oxide catalysts.