Study On Carbon–doped Titanium Dioxide Supported Pt–based Catalyst For Direct Methanol Fuel Cell

Direct methanol fuel cell is an ideal energy storage device for new energy vehicles.Commercial Pt/C as a fuel cell catalyst has shortcomings of low catalytic activity and poor stability,which severely hinders its application in the commercial field.Comparing with carbon materials,metal oxides have metal-metal oxide interactions,and at the same time have higher mechanical strength,and are more stable as platinum-based catalyst supports.However,the electrochemical resistance of metal oxides is relatively large,which is not conducive to the electrochemical reaction process of the catalyst.In this paper,the metal oxides is modified by introducing heteroatoms.By using plasma electronic chemical vapor deposition（PECVD）method to directly synthesize carbon-doped TiO₂-C carrier material,and finally using microwave method to load Pt on the TiO₂-C carrier to prepare Pt/TiO₂-C catalyst.Comparing with carbon support materials,the introduction of carbon doping can effectively adjust the electronic structure and surface state of TiO₂.Carbon doping to form electron holes increases the electron cloud density on the surface of TiO₂.At the same time,the doping process introduces a large number of defects on the surface of TiO₂,which is more conducive to the loading of Pt on the surface of TiO₂ carrier.The electrochemical test results show that the carrier prepared at500℃has the best performance after carrying platinum.Its methanol oxidation peak current density is twice that of commercial Pt/C,and its long-cycle stability is also excellent.The current retention rate after 5000 cycles is 4 times that of commercial Pt/C.At the same time,in the full battery performance test,the maximum power density of the Pt/TiO₂-C catalyst is close to 85 mW·cm^-2,while the maximum power density of the Pt/C catalyst is only 55mW·cm^-2.On the basis of the previous chapter,using melamine as nitrogen source,the N element was further introduced by PECVD method to prepare TiO₂-N-C carrier material.Since the formation of N-C coordination plays a role in fixing Pt particles,in addition,the doping of N enhances the interaction between platinum and TiO₂ in the catalyst,thereby helping to improve the stability of the catalyst.The electrochemical test results show that the performance of the nitrogen-carbon co-doped catalyst is significantly better than that of the carbon-doped catalyst.The methanol oxidation peak current density of the Pt/TiO₂-N-C catalyst is 13.6%higher than that of the Pt/TiO₂-C.The current density of the Pt/TiO₂-N-C catalyst in the constant potential time current test retains 42.5%of its maximum value,which is far it is higher than 17.1%of Pt/TiO₂-C.The maximum power density of the Pt/TiO₂-N-C catalyst is 90 mW·cm^-2 in the full battery testing.