Excellent stability for catalytic oxidation formaldehyde over defective δ-MnO2 nanoparticles at room temperature

Abstract

Engineering oxygen vacancies on δ-MnO2 is an efficient strategy to generate active oxygen species for boosting its catalytic activity towards HCHO oxidation. In this work, a reductant-based redox method was employed to enrich the oxygen vacancies on δ-MnO2 catalysts. Different reductants, such as methanol, ethanol and isopropanol, were employed during preparation process and studied for their effects on catalytic activity and stability of δ-MnO2 catalysts towards formaldehyde degradation. The MnO2-Iso sample prepared by isopropanol as reductant shows excellent stability and catalytic activity. In the six cycling tests, the formaldehyde removal efficiency keeps above 90% during 15 h per test. The isopropanol weakens the van der vaals force between the interlayers of MnO2-Iso catalyst and promotes the generation of active oxygen species. The balance between consumption and generation of hydroxyl groups is responsible for the excellent stability of MnO2-Iso catalyst. This work provides theoretical support for widespread commercial application of δ-MnO2 with nanoparticle structure in the decomposition of indoor formaldehyde at room temperature.