Study On Modification Of Active Component And Support Regulation Of Anode Catalysts Pt/C For Direct Ethanol Fuel Cells

The extensive use of fossil fuels has made the problem of environmental pollution increasingly serious,triggering the continuous exploration and development of sustainable clean energy and its equipment.Ethanol fuel has a wide range of sources and can be obtained by fermentation of biomass.As a green and environmentally friendly renewable energy with high energy density,ethanol fuel is widely favored by people.Correspondingly,as a device for converting chemical energy into electrical energy,direct ethanol fuel cells（DEFCs）are also highly sought after.However,the commercialization of direct ethanol fuel cells still face many problems,and the electro-oxidation of ethanol still has great challenges.Currently,Pt/C catalysts are the most commonly used anode catalysts for direct ethanol fuel cells in acidic media.However,Pt is easily poisoned by CO,an intermediate product of ethanol oxidation,resulting in the formation of Pt-CO_ads,which ultimately leads to the degradation of the electrochemical performance of Pt-based catalysts.Therefore,it is essential to develop Pt-based catalysts with excellent electrochemical performance and excellent resistance to CO poisoning.This paper focuses on improving the activity,durability,stability and anti-CO poisoning ability of the catalyst,and the effects of active components and supports on the electrochemical performance of catalysts were investigated.It mainly includes the following aspects:（1）Modifying the catalyst C/UO₂/Pt previously designed by this research group to solve the problem that uranium dioxide was easily lost in acidic solution,and realized the"self-reactivation"of the catalysts.In the experiments of this chapter,UO₂was coated with polymer polyvinylpyrrolidone（PVP）to reduce its loss,and C/UO₂/PVP/Pt catalysts with different PVP contents were prepared.The morphology,structure and composition were characterized by XRD,TEM,XPS,ICP-MS and so on.The electrochemical performance of the catalysts were tested by electrochemical workstation,and compared with Pt/C and C/UO₂/Pt catalysts.At the same time,the mechanism of action of UO₂to alleviate Pt poisoning was further expounded.The results showed that when the PVP loading is 10%,compared with the C/UO₂/Pt catalyst,the UO₂loss of the C/UO₂/PVP/Pt catalyst decreased from 43.18%to 10.14%,and the electrochemical performance was also greatly improved.The electrochemical activity was 1.5 times that of the C/UO₂/Pt catalyst and 2 times that of the Pt/C catalyst,and the durability was1.25 times that of the C/UO₂/Pt catalyst and 1.33 times that of the Pt/C catalyst.（2）In order to further improve the electrocatalytic activity of the catalyst,the support of the catalyst was adjusted.Pt-UO₂/C:N-CNTs（x:y）catalyst was prepared by introducing nitrogen-doped carbon nanotubes as a carrier,and by adjusting the ratio of carbon black and nitrogen-doped carbon nanotubes as a mixed carrier.At the same time,the effect of nitrogen-doped carbon nanotubes on UO₂and Pt particles was investigated.Physical characterization and electrochemical performance testing of the prepared catalysts were conducted.And electrocatalyst with excellent electrochemical performance was identified.The experimental results showed that when the ratio of carbon black and nitrogen-doped carbon nanotubes was 2:3,the catalyst showed good electrochemical performance.Due to the interaction between N atoms and Pt atoms,the loss of Pt was greatly reduced.Compared with the Pt-UO₂/C catalyst,the Pt loss rate decreased from 10.51%to 4.25%.At the same time,the large pore size of nitrogen-doped carbon nanotubes made the reactants and catalysts fully contact,so that UO₂could fully play the role of alleviating Pt poisoning,and finally realized the"self-cleaning"of the catalysts.The electrochemical activity and durability were also significantly improved.The electrochemical activity was 1.6 times that of the Pt-UO₂/N-CNTs catalyst and 1.9 times that of the Pt/C catalyst,and the durability was 1.31 times that of the Pt-UO₂/N-CNTs catalyst and 1.33 times that of the Pt/C catalyst.（3）In order to further improve the electrocatalytic activity of the catalyst,introducing the rhenium（Re）element to conduct exploratory experiments,the bimetallic Pt-Re/C alloy catalyst was prepared by the co-reduction method.And by adjusting the platinum-rhenium ratio,electrocatalysts with excellent electrochemical properties were identified.Electrochemical test results showed that when the ratio of platinum to rhenium was 1:1,the catalyst exhibited excellent electrochemical performance.Compared with Pt/C,the electrochemical activity,durability and stability were greatly improved,and the resistance to CO poisoning was also improved.The electrochemical activity of the Pt₁-Re₁/C catalyst was 5.41 times that of the Pt/C catalyst,the durability was 1.77 times that of the Pt/C catalyst,and the stability and resistance to CO poisoning were 16.88 times that of the Pt/C catalyst.