Insight into the Crystal Structures and Surface Property of Manganese Oxide on CO Catalytic Oxidation Performance.

α-MnO nanorods and flower-like γ-MnO microspheres were synthesized by facile and mild methods to illustrate the effect of crystal structures and surface features on catalytic performance with the help of carbon monoxide (CO) oxidation. It is revealed that the flower-like γ-MnO microspheres possess better catalytic oxidation performance (CO complete conversion temperature at 120 °C and long-time stability for 50 h) than α-MnO nanorods, which can be attributed to the obvious differences in the chemical bonds and linking modes of [MnO] octahedra due to the different crystal structures. γ-MnO possesses lower Mn-O bond strength that enables γ-MnO to present a large amount of surface lattice oxygen and superior oxygen mobility. The disordered random intergrowth tunnel structure can adsorb effectively CO molecules, resulting in excellent catalytic performance for CO catalytic oxidation. In addition, the MnO catalyst probably occurred via a Mars-van Krevelen mechanism for CO oxidation. This work provides an insight into the effect of crystal structures and surface property of manganese oxide on catalytic oxidation performance, which presents help for the future design of promising catalysts with excellent catalytic performance.