Investigation In The Catalytic Performance Of Nano-manganese Oxide And Its Effect On The Tribological Property Of Polytetrafluoroethylene

Manganese dioxide(Mn O2), as a common metal oxide with advantages of excellent electrochemical catalytic properties, low price and wide resources, has been widely used in catalyzing the oxygen reduction reactions in batteries and supercapacitances. Oxygen reduction reactions have played an important role in the electrochemistry field such as fuel cells and biological sensors; thus, manganese dioxide has attracted tremendous attention in electrochemical field.Firstly, α-Mn O2, β-Mn O2 and their composites(incorporated by activated carbon,acetylene black and graphite oxide) were prepared successfully by a hydrothermal synthesis method. The techniques of X ray diffraction(XRD), Scanning electron microscope(SEM) and Transmission electron microscope(TEM) were applied to characterize the morphology of the as-prepared materials. Then cyclic voltammetry(CV),linear sweep voltammetry(LSV), electrochemical impedance spectroscopy(EIS) and tafel polarization were employed to investigate the catalytic properties of oxygen reduction reaction(ORR), and the mechanism of ORR was discussed briefly. The results show that the catalytic performance of ORR for the two Mn O2 samples follows the order: α-Mn O2 >β-Mn O2. To some extent, the addition of acetylene black could enhance the ORR properties of Mn O2. Compared with other composites, the Mn O2/acetylene black composite shows the best enhancement in the ORR performance.Secondly, the application of Mn O2 catalyzing H2O2 to degrade methylene blue was discussed. The α-Mn O2/graphite oxide-H2O2 system shows the most significant effect on the degradation of the dye, and the degradation rate can reach 92.4% which is a 60%increase over the α-Mn O2-H2O2 system. In addition, the degradation process of methylene blue belongs to the Fenton-like reaction, and the dye decolorization rate depends on the addition of catalyst and H2O2. In order to achieve the ideal degradation efficiency on the dyes, a suitable addition of catalyst and H2O2 should be selected.Finally, the tribological properties of α-Mn O2/PTFE and β-Mn O2/PTFE on different dry sliding conditions were studied, combining with the techniques of XRD, SEM, EDSand TG. The results show that the addition of α-Mn O2 and β-Mn O2 can remarkably improved the tribological property of PTFE. Moreover, the wear rates of β-Mn O2/PTFE are far less than that of α-Mn O2/PTFE, which guarantees the better wear-resisting performance of β-Mn O2/PTFE. Of all the samples of Mn O2/PTFE, the β-Mn O2/PTFE containing β-Mn O2 of 10 wt% possess the best tribological property.