Preparation And Properties Of Catalysts For Direct Formate Fuel Cells

Direct formic acid fuel cell?DFFC?is a kind of non-toxic salt and high conversion efficiency of green energy,which has attracted more and more attention in recent years.Catalyst is an important part of DFFC.The development of catalyst with good performance and low cost is of great significance for the commercial use of DFFC.So,the following work has been carried out in this paper:?1?Ag-SnO₂ series composite catalysts were prepared for oxygen reduction reaction?ORR?.Electrochemical characterization showed that compared with the catalyst covered with Ag on the surface of SnO₂,the catalytic activity of ORR was higher when Ag was partially covered with SnO₂,which indicated that SnO₂ could promote the catalytic activity of Ag for ORR.The activity of Ag catalyst and Pt catalyst in different concentration of KOH solution for ORR was studied.It was found that the catalyst had the best catalytic activity when the concentration of alkali was 0.1 M.By depositing Ag,Pd and Pt on the surface of Sn?OH?₂ and then dissolving Sn?OH?₂,a series of catalysts were prepared.Compared with the catalysts without dissolution treatment of SnO₂,it was found that the catalytic activity and stability of Ag,Pd and Pt were higher in the presence of SnO₂.The results showed that SnO₂ had synergistic effect on the activity and stability of ORR catalyzed by Ag,Pd and Pt.?2?In order to explore the synergistic effect of Ag and Pd on ORR,a series of Ag-Pd catalysts were prepared by chemical method.It was found that the mass specific activity of Pd-based catalysts with Ag elements was improved,which proved that Ag-Pd had synergistic effect.In order to further improve the utilization rate of Pd in Ag-Pd catalyst,Pd-Ag-SnO₂/CNTs series catalysts were prepared by Pb underpotential deposition and displacement reaction.Electrochemical tests showed that the catalyst prepared by electrochemical method had higher specific activity than that prepared by chemical method.?3?In order to compare the effects of surface effect and scale effect on the activity and anti-toxicity of formate oxidation,Pd catalysts with partially and completely covered SnO₂ surface were prepared and found by electrochemical test.The toxicity resistance of partially covered catalyst is obviously better than that of full covered catalyst.On the basis of Pd catalyst partially covered with SnO₂,a series of catalysts with different Pd scales were prepared by subsequent Pd growth.The results showed that the increase of Pd scale had a significant synergistic effect on the catalyst performance.