| Anode catalyst is the most critical component of Direct Methanol Fuel Cell（DMFC）,and its activity is the key to affecting DMFC performance.Currently,commercial catalysts are mostly precious metal catalysts.High price,complex preparation process,sintering of catalyst particles,and susceptibility to the poisoning of methanol oxidation reaction severely restrict the commercial application of DMFC.Metal organic framework（MOF）material has the structural characteristics of rich pores and large surface area,making it a potential choice for non-precious metal catalysts.In this experiment,MOF was used as the precursor to synthesize non-precious metal catalysts for methanol fuel cells,and the structure,morphology and electrochemical performance of the catalysts were tested and analyzed.The specific research carried out is as follows:（1）ZIF-8 and Ni-MOF were synthesized by liquid phase diffusion method and hydrothermal method,respectively.Ni-based catalysts are compounded by grinding and high-temperature pyrolysis.Characterization methods such as SEM,XRD and CV cycle were used to explore the effect of preparation temperature on the morphology and activity of the catalyst.The study found that when the preparation temperature is 850℃,the catalyst has the best catalytic performance,and the influence of temperature on the morphology and activity of the catalyst is analyzed.And the structure,morphology and activity of the catalyst prepared under different atmosphere conditions at 850℃were explored.The catalyst prepared under the Ar atmosphere has more excellent catalytic activity than the catalyst prepared in the air.The analysis shows that the Ar atmosphere conditions are beneficial to the preservation of the C carrier and the improvement of the catalyst dispersion.Therefore,under the conditions of 850℃and Ar atmosphere,the influence of different ratios of ZIF-8 and Ni-MOF was explored,and the catalyst ZIF-8/Ni-MOF-4 with the best quality activity and stability was screened out.Its quality activity is 57.0mAmg-1,and the current density is maintained at 95%without significant attenuation within 8000 s.ZIF-8/Ni-MOF-4 has the largest electrochemically active specific surface area among several catalysts,which is 52.4cm2mg-1,indicating that the catalyst has a large number of active sites.In addition,ZIF-8/Ni-MOF-4 has the lowest electrochemical impedance among several catalysts,indicating that the catalyst has the lowest charge transfer resistance,and the catalyst has excellent catalytic performance.（2）The Cu-BTC metal-organic framework was synthesized by hydrothermal method.The Cu-BTC and Ni-MOF metal organic frameworks are put together by grinding and further high temperature pyrolysis synthesis Ni-based catalyst.The effects of different Ni content and Cu content on the methanol oxidation activity of the catalyst were explored.It is analyzed that the introduction of Cu element greatly improves the catalytic activity of the catalyst.Among several catalysts,Cu-BTC/Ni-MOF-2 has the best electrocatalytic activity,and its mass activity is 311.6mAmg-1.Moreover,Cu-BTC/Ni-MOF-2 has relatively excellent electrochemical stability.After 8000s,Cu-BTC/Ni-MOF-2 still maintains the largest current density among several catalysts,which is 80%of the initial current density.In addition,Cu-BTC/Ni-MOF-2 has the largest electrochemically active specific surface area and the lowest electrochemical impedance among several catalysts.Its electrochemically active specific surface area is26.7cm2mg-1,indicating that it has the most active site.The smallest electrochemical impedance indicates that it has the lowest charge transfer resistance,which lays the foundation for the excellent performance of the catalyst. |
