Study On The Preparation Of Fuel Cell Catalysts From Triblock Copolymers And Their Catalytic Performance

The development and utilization of sustainable new green energy have become the top priority because of over use of fossil fuels and serious environmental pollution with increasingly scarce resources in the modern society.Fuel cell is the power-supply device that has high energy conversion efficiency and is friendly with environment.As fuel cell cannot be affected by the Carnot efficiency,it directly converts the chemical energy into electric energy and reduces the energy loss in the reaction.Due to its particular characteristics such as environmental and clean,the fuel cell is considered to be the green energy resource for the 21 st century,and may make the “hydrogen economy” possible.For the anodic methanol oxidation reaction(MOR),the most effective catalyst material of direct methanol fuel cells(DMFCs)is Pt.However,Pt is very expensive,and it is easily poisoned by the CO-like intermediates during the process of methanol oxidation,which has some effect on the catalytic performance of Pt catalysts.Therefore,enhancing the catalytic properties and anti-poisoning ability of Pt catalyst is significant.Nevertheless,Ethylene glycol is a feeble reducing agent,so it is not suitable for the preparation of various combinations of catalysts.In this work,to enhance the catalytic properties and the stability of Pt catalyst,ethylene glycol is replaced by triblock copolymer.Because of their low toxicity and amphi-philic nature,they are used to rationally design the Pt-based catalysts and PtRu alloy catalyst.Then the effect of catalytic agents with different pH values on its electro-catalytic property and stability is designed.The Pt-based catalysts and PtRu alloy catalyst for direct methanol fuel cells(DMFC)were prepared by the liquid reduction method using two kinds of triblock copolymer as the reducing agent,and using Vulcan XC-72 carbon as the substrate.The catalysts are comprehensively characterized by TEM,EDS,XRD and electrochemical techniques including cyclic voltammetry(CV)and chronoamperometry(CA).The details of this study are as follows:1.The Pt/C electrocatalysts supported on vulcan XC-72 carbon were prepared using P123 as reducing and stabilizing agent by varying the pH value of 2-6.The results of XRD show that the Pt/C catalyst was successfully synthesized,and the TEM results show that the particle distribution of the catalyst was uniform and matched with the result of XRD.It can be seen from the electrochemical test that the catalyst with pH value of 2—6 has a good effect on the catalytic oxidation of methanol.When the pH value is 4,the Pt based catalyst obviously exhibits better electrocatalytic effect and better stability than other pH values.2.The PtRu/C electrocatalysts supported on vulcan XC-72 carbon were prepared using P123 as reducing and stabilizing agent by varying the pH value of 2-4.It is observed in XRD that due to the obvious shift of the characteristic peaks to the right side and the absence of Ru corresponding characteristic peaks,Ru is incorporated into the crystal structure of Pt,and the PtRu alloy crystal has been successfully synthesized.The electrochemical results show that the promoter Ru can significantly improve the catalytic performances and anti-poisoning of Pt in alkaline medium.When the pH value is 3,the catalytic effect of the Pt Ru/C alloy catalyst is obviously better than that of the others.3.The Pt/C electrocatalysts supported on vulcan XC-72 carbon were prepared using F108 as reducing and stabilizing agent by varying the pH value of 2-4.was prepared by the liquid reduction method,which can be proved in the XRD results.The electrochemical results show that when the pH value is 4,the catalyst shows better electrocatalytic effect and stability.