| Direct methanol fuel cells is a type of environment-friendly battery featuring simple architecture and pollution-free energy conversion process,which has wide applications in the field of clean energy.In a typical raditional commercial electrode,carbon black is used as the substrate loading nobel metal catalyst such as Pt.However,carbon black can be easily etched by the corrosive working environment.On the other hand,noble metal Pt catalyst greatly increases the cost of the battery,which hinders the commercialization of fuel cells.In this paper,TiO2 and Ti(N,O)nanowires with three-dimensional architecture have been prepared by combining hydrothermal method,magnetron sputtering method and chemical vapor phase method.Pt nanoparticles and ultrafine Pt nanowires and PtCu alloy were prepared by the method of formic acid reduction.The electrocatalytic performance of the composite catalyst was systematically investigated.Main results of the research can be summarized as follows:(1)The anatase TiO2 nanocrystals were prepared by hydrothermal synthesis method.The growth of TiO2 nanowires and nanobelts could be controlled by adjusting the temperature and alkalinity.The obtained high aspect ratio of the TiO2 nanowire arrays,the diameter of the TiO2 nanowires have a distribution between 50-100 nm and a length of 1-10 μm.(2)A thin TiN thin film was sputtered on the surface of the TiO2 nanowire arrays by magnetron sputtering followed by nitriding treatment of TiO2 nanowires in ammonia under high temperature.The effects of nitriding temperature on the phase and morphology of TiO2 was investigated,and the phase transition from TiO2 into TiN was realized.Finally,the TiN/TiO2 samples prepared at 800° C nitriding temperature were selected as a carrier for loading metal catalysts.(3)The Pt/TiO2 composites were successfully prepared by a formic acid reduction method on the TiO2 nanowires,and Pt nanoparticles and ultrafine Pt nanowires were obtained on the nanowires.Compared with the Pt/Ti-mesh composites,Pt/TiO2 composites exhibit better electrocatalytic performance and stability for methanol oxidation,which may due to synergistic effect between TiO2 nanowires and nanostructured Pt.(4)The Pt/TiN/TiO2 composites were successfully prepared by a formic acid reduction method on the nitrided TiO2 nanowires,in which Pt nanoparticles andultrafine Pt nanowires were loaded on the nanowires.Compared with the Pt/C commercial catalysts,Pt/TiN/TiO2 composites show better electrocatalytic activity and stability owing to excellent electrical conductivity,corrosion resistance and stability of the nanostructured TiO2 after nitriding treatment.(5)PtCu/TiN/TiO2 composites were successfully prepared by a formic acid reduction method on the nitrided TiO2 nanowires.Electrocatalytic properties of the PtCu/TiN/TiO2 composites were determined with different Pt/Cu ratio,and the results indicated that the sample suggested better electrocatalytic performance with the increase of Cu content within a certain range.When the ratio of Pt and Cu is 3:1,the alloy catalyst exhibited highest catalytic performance for methanol oxidation. |
