Nickel doping MnO2 with abundant surface pits as highly efficient catalysts for propane deep oxidation.

Graphical abstract Highlights • MnNi x oxides with irregular pits were synthesized via hydrothermal method. • The addition of Ni into MnO 2 promoted the catalytic activity for propane oxidation. • The MnNi 0.09 sample could convert 90% propane at 220 °C. • The MnNi 0.09 sample with pits exhibited the lowest apparent activation energy (33.6 kJ mol−1). Abstract Series of nickel doping MnO 2 with irregular surface pits were synthesized and employed for propane deep oxidation. The partial substitution of Ni for Mn resulted in the formation of structural defects, which could be observed by high-resolution transmission electron microscopy. The MnNi 0.09 sample exhibited the best catalytic activity for propane oxidation with the conversion of 90% at 220 °C. The presence of pits on the MnNi 0.09 sample could facilitate the dissociation of propane and mobility of oxygen along the conduction channels of surface pits, thus promoting the catalytic efficiency. Moreover, the in situ studies found that different intermediates were formed on the MnO 2 and MnNi 0.09 catalysts during the propane oxidation process. The propane was oxidized to propanoyl species on the surface of MnO 2 catalyst, while it was oxidized to hydrogen carbonates and carbonates on the surface of MnNi 0.09 sample, which were thermally less stable and converted into CO 2 at lower temperature. The finding provides a new perspective on understanding the effect of cation doping. [ABSTRACT FROM AUTHOR]