Manganese-doped cobalt tetroxide for formaldehyde oxidation

Cobalt-based oxides are appealing but less-well investigated catalytic materials for formaldehyde (HCHO) oxidation. We herein report a careful study of carbon-supported Co3−xMnxO4 catalyst, with special focuses on the incorporation of Mn ions into Co3O4 lattice and its effect on the catalytic activity for HCHO oxidation. The Co3−xMnxO4/C catalysts were fabricated using a co-precipitation method followed by annealing treatment. A combination of phase structure/chemical structure analyses and control experiments confirmed the substitutional doping of Mn ions in Co3O4 lattice, which resulted in increment of oxygen vacancy concentration. Benefiting from Mn-doping and the dispersion effect of carbon, the Co2.7Mn0.3O4/C catalyst prepared under optimal conditions exhibited an impressively high activity for HCHO oxidation, fairly good stability and excellent moisture tolerance. For instance, it enabled a 100% HCHO conversion at 90 °C with a ten-fold higher mass-specific activity compared to Co3O4/C. A possible mechanism describing the HCHO oxidation over Co3−xMnxO4/C catalyst was proposed based on the in situ diffused reflectance infrared spectroscopy results.