Study On The Preparation And Electro-catalytic Performance Of Pt-Ag-Co Alloy Nano-particles As Cathode Catalysts For Direct NaBH₄-H₂O₂ Fuel Cells

Direct NaBH4/H2O2 fuel cells (DBHFCs), as the new research direction of alkaline fuel cell, have been wildly concerned due to their high conversion efficiency, high specific energy, non-polluting, the raw materials easy to storage and transport, being used in underwater, space and some special environment. Currently, due to the investigation of anode catalyst being successful relatively, scientists and researchers are devoting to the research of cathode catalyst. Noble metal Pt is the major candidate for the cathode catalyst of this kind of fuel cell. While the limited resource and higher cost of Pt has greatly limited the business applications of DBHFCs. Therefore, preparing a new type of catalyst, which can instead of Pt and maintain high catalytic activity for H2O2 electro-reduction, has been being a hot research.In this paper, by using impregnation-reduction method, we prepared the Pt-Ag/C and Pt-Ag-Co/C catalysts at different reduction reaction time (2h,3.5h,5h) and different mass ratios of Pt-Ag and Pt-Ag-Co on the carbon VulcanXC-72. All of them were characterized by TEM and XRD. Their electrochemical performance were tested by CHI660d electrochemical workstation at different temperatures (20℃,25℃,30℃,40℃), different electrolyte(NaOH) concentration (0.5M,1M,2M,3M) and different reactants(H2O2) concentration (0.03M, 0.1M,0.15M,0.2M) in acidic and alkali medias respectively. The XRD and TEM results show that the catalysts are all the face-centered cubic structure, and their particles can be well distributed on the carbon support. The diameter of binary catalyst particles is about 10nm, while the size of three-way catalyst particles is about 2-4nm. The CV results show that replacing Pt by Ag to form the Pt-Ag/C alloy catalyst has improved the catalytic activity in some extent. While the catalytic effect of Pt-Ag-Co/C is superior to Pt-Ag/C when the metal Co is introduced into Pt-Ag/C catalysts.The EIS curves of Pt5-Ag10-Co15/C and Pt10-Ag10-Co15/C catalysts were measured at 25℃. We assembled two NaBH4/H2O2 fuel cells, their cathode catalysts were Pt5-Ag10-Co15/C and Pt10-Ag10-Coi15/C respectively, their anode catalysts were both commercial Pt/C (40%). The constant current discharge curves of these two cells were tested in 0.06mol/L and 0.2mol/L H2O2 respectively, and then we calculated the power density of them. The results show that the cell with the Pt10-Ag10-Co15/C cathode catalyst has the best battery performance in 0.2mol/L H2O2, and the maximum power density can reach 110.7mW/cm2.