Study On Preparation Of Proton Exchange Membrane Fuel Cell Composite Catalyst And Its Resistance To Sulfur

In face of the severe environmental challenges facing the human,due to the proton exchange membrane fuel cell has its advantage of high energy conversion rate,rapid start,zero emissions,etc,which has wide prospect in a new energy vehicle power,mobile decentralized power station.Currently,the impurity gas on the catalyst poisoning and the high cost generated by the use of noble metal seriously obstruct the promotion of the proton exchange membrane fuel cell.The impurity gas contained in the ambient air can have a negative impact on the battery,especially the sulfur-containing impurities are the most toxic to the battery.Increasing the tolerance of the catalyst to the absorbed SO₂ can greatly improve the durability of the catalyst.In addition,due to the use of noble metal as the main catalytic component of the catalyst and the complexity of the commercial craft,led to high cost.Therefore,reducing the amount of the catalyst while optimizing the preparation of the catalyst is an important process to promote the commercialization of fuel cells.In this paper,we use disposed XC-72 carbon as supporter,transition metal nickel and its main group element palladium as the precursor,prepared nickel,palladium as the core,platinum as the shell nano-size catalys by two-step chemical reduction and colloid method.The structure,morphology and electrochemical properties of the electrocatalyst were characterized by FT-IR,HRTEM,XRD,LSV,CV and compared with the same Pt amount of commercial Pt/C catalyst.The details are as follows.The Pt/C catalyst was prepared by optimized the preparation process and compared catalytic activity with commercial Pt/C catalyst.The optimum preparation conditions were explored and clarified reaction conditions for the preparation of the subsequent core-shell catalyst.The experimental results showed that the catalyst under XC-72 diposed with HNO₃as carrier and ethylene glycol as reducing agent has high loading and the electrochemical area is larger than commercial Pt/C?JM?catalyst.The Ni@Pt/C catalyst was prepared by chemical two-step reduction method.The presence of core-shell structure was confirmed by TEM and XRD and the outer Pt was uniformly loaded on the surface of Ni core.The results of electrochemical tests through CV and LSV showed that the maximum electrochemical area of the prepared Ni-core catalyst was53.7 m²/g.The decay rate was 36%better than 81%of the pure Pt/C catalyst after 1000durability tests.In addition,it also showed a certain tolerance in the anti-sulfur test,electrocatalytic oxidation of the catalyst after poisoning was carried out,and its oxidation potential was shifted by 25 mV.In order to further improve the durability of the catalyst and SO₂ tolerance,the next main group element Pd was used as the core metal,and the precursor was prepared by sodium borohydride colloidal protective agent method before loading Pt.The results of XRD show that Pd core catalyst has a better crystal form,although its electrochemical active area is 46.5m²/g and slightly lower than Ni core catalyst,but its durability and resistance to sulfur has been greatly improved,after the 1000 durability test,the decay rate of the catalyst is only28%,the SO₂ oxidation potential negative shift is 60 mV,and linear voltammetry test results showed that it had higher oxygen reduction potential which contributed to four electron reactions.