Engineering\nManganese Defects in Mn₃O₄ for Catalytic Oxidation\nof Carcinogenic Formaldehyde

Abstract

Formaldehyde\n(HCHO) is a priority pollutant in the indoor environment,\nwhich is irritative and carcinogenic to humans. The non-noble metal\noxides have a wide application prospect in the decomposition of HCHO.\nDefects in metal oxides have been widely accepted as active sites\nin heterogeneous catalysis. Compared with the extensive study of oxygen\ndefects, the effect of cation defects has not been clearly addressed.\nHerein, Mn defect-rich Mn₃O₄ was synthesized\nby pyrolysis of Ce-doped MnCO₃. It is found for the first\ntime that the content of Mn defects in Mn₃O₄ can be adjusted by introducing Ce. The introduction of Ce resulted\nin the higher contents of Mn defects, which significantly enhances\nthe HCHO decomposition. Moreover, Mn defect can effectively narrow\nthe half-metallic gap of Mn₃O₄, regulate the\nelectronic structure and coordination environment of surrounding oxygen,\nand further improve the activity and mobility of neighboring oxygen\natoms. Importantly, Mn defects are not only beneficial to the generation\nof neighboring oxygen vacancy but also conducive to enhancing the\nactivation ability of oxygen vacancy for O₂. The advantages\nresulting from Mn defects significantly enhance the HCHO decomposition.\nThis research proposes a strategy to adjust cation defects and deepens\nthe comprehension of the function of cation defects.