Preparation And Catalytic Properties Of PtTi Based Alloys

As a new generation of energy conversion power generation system,direct ethanol fuel cell has attracted wide attention because of its great application potential.At present,the key factors restricting the large-scale commercialization of direct methanol fuel cells are cost and life.Pt catalyst,which occupies a large cost,is an important part of fuel cell.In addition,the structure of Pt catalyst is very unstable and fall off,resulting in irreversible loss,which is one of the important factors affecting its life.Therefore,the preparation of Pt-based catalysts with high activity,more stability,and less precious metal consumption is an urgent problem to be solved.Magnetron sputtering can achieve Pt load uniformly controllable and ultra-low load.Therefore,magnetron sputtering technology can be used as an important method to reduce the cost.This paper aims at the above problems,a layer of pure Pt catalyst was sputtered directly on acid-treated Toray carbon paper,and metal Ti and Mg were added.Its structure was characterized by SEM,XRD,EDS,TEM,and CV,DST,CA test was carried out in the acid electrolyte of a three-electrode system to explore the ability of electrocatalytic oxidation of ethanol.The specific research contents and conclusions are as follows:1.By means of controlling different sputtering pressure,Pt with a load of 0.1 mg/cm~2 was deposited on carbon paper,in which the substrate carbon paper before deposition was soaked in 2 M sulfuric acid solution,which was compared with that treated with deionized water only.Through the test and analysis,it is concluded that when the carbon paper is treated with acid and the sputtering pressure is 0.01mbar,the performance of the catalyst Pt is the best,and its electrochemical activity area and peak current density are 163.33 m~2/g and 0.445A/mg,respectively.2.To explore the effect of PtTi catalysts with different element ratios of Pt and Ti on the catalytic performance.Pt and Ti were co-deposited on acid-treated carbon paper by magnetron double-target co-sputtering.Based on controlling a load of Pt to 0.1 mg/cm~2,the content of Ti in Ti target sputtering power control alloy was adjusted.In the PtTi catalyst,when the element content ratio is 79:21 and the average particle size is 8.7 nm,the electrochemical activity area and peak current density are the highest,which are 186.14 m~2/g and 1.178 A/mg,respectively.After in-situ annealing,although the electrochemical activity and peak current density decreased,its stability was greatly improved.It shows that the addition of a certain amount of Ti element can promote the activity and stability of the catalyst to a certain extent.3.To explore the effect of PtTiMg ternary catalyst with different Mg content on the catalytic performance.PtTiMg catalyst was prepared by three-target co-sputtering.When the sputtering power of the Mg target is 30W,the sample shows excellent ethanol oxidation ability and cycle stability.On this basis,by soaking the samples in strong acid,it was found that the electrochemically active area and peak current density decreased obviously,but the peak current density(1.411 A/mg)was significantly higher than that of pure Pt.Therefore,under the same performance conditions,the addition of Ti and Mg can greatly improve the catalytic activity of ethanol and the durability of the catalyst itself.Through the above systematic analysis,the acid-treated substrate and the PtTiMg catalyst prepared by the co-sputtering process can greatly improve the electrochemical performance of the catalyst.