Controlled synthesis of tunnel-structured MnO2 through hydrothermal transformation of δ-MnO2 and their catalytic combustion of dimethyl ether

Abstract Synthesis of tunnel-structured MnO 2 with one-dimensional morphologies (α-MnO 2 nanowires and β-MnO 2 nanorods) is reported, which is based on the hydrothermal transformation of layer-structured MnO 2 with two-dimensional morphology (δ-MnO 2 nanosheets) via altering the reaction conditions readily. The types of the anions (SO 4 2- and Cl - ) in the acid solution play critical roles in determining the crystalline structures of the final products. Both of the MnO 2 samples were characterized by means of XRD, Raman, FESEM, TEM, BET, XPS and H 2 -TPR techniques. Owning to its more abundant surface adsorbed oxygen species, stronger reducibility, larger specific surface area and lower Mn-O bond strength, the α-MnO 2 nanowires showed enhanced catalytic performance in the dimethyl ether catalytic combustion ( T 10 = 200 °C and T 90 = 274 °C at WHSV = 30,000 ml g −1 h −1 ), which was much higher than the β-MnO 2 nanorods.