Oriented growth of δ-MnO2 nanosheets over core-shell Mn2O3@δ-MnO2 catalysts: An interface-engineered effects for enhanced low-temperature methanol oxidation

•The pure manganese oxides Mn2O3@δ-MnO2 core-shell structures can be fine-manipulated via a novel synthesis method.•The synergistic effect of δ-MnO2 nanosheets and Mn2O3 microspheres is the key to enhance the deep methanol oxidation.•The Mn2O3@δ-MnO2 interface structure exhibited more Mn4+, well redox ability and active surface lattice oxygen.•Activity study revealed that the Mn2O3@δ-MnO2-8h catalyst has excellent activity for low-temperature methanol oxidation. In order to elucidate the special role of interfacial effect over nanomaterials in the catalytic oxidation of volatile organic compounds (VOCs), a series of core-shell Mn2O3@δ-MnO2 catalysts with different degree of oriented growth were prepared by a hydrothermal method, which were applied for methanol oxidation. Besides, the structure-activity relationship over the core-shell Mn2O3@δ-MnO2 catalysts was further explained in details by multiple characterization techniques. It was found that the strong metal-support interaction promoted the formation of the interface between Mn2O3 and δ-MnO2, which significantly changed the physicochemical properties and catalytic behaviours of core-shell Mn2O3@δ-MnO2 catalysts. Among all the catalysts, the catalytic performances of these core-shell catalysts were obviously better than those of pure δ-MnO2 nanosheets and Mn2O3 microspheres, and the Mn2O3@δ-MnO2-8h catalyst exhibited the best outstanding activity for methanol oxidation (T90 = 119 °C). In addition, the characterization analyses showed that the interfacial effect derived from the interaction between Mn2O3 and δ-MnO2 can increase the amount of Mn4+, and surface lattice oxygen, as well as optimize the low-temperature reduction ability, which was the crucial reason for the high activity of above core-shell Mn2O3@δ-MnO2 catalysts. [Display omitted]