Preparation And Electrocatalytic Propertyies Of Pt-based Alloy Catalysts

The rapid consumption of fossil fuels leads to severe energy crisis and environmental pollution.As promising devices,fuel cells have attracted extensive attention due to their clean and sustainable energy conversion.For now,the main catalysts for commercial fuel cells are commercial Pt/C catalysts.However,the scarcity,high cost,as well as CO poison of Pt hinder the development of fuel cells.In order to reduce the usage of Pt and increase the electrocatalytic activity,alloying Pt with other metals is an efficient method.Besides,it’s reported that the nanocrystals with specific morphology tend to exhibit much higher electrocatalytic activity.Therefore,designing high-performance and high-stability Pt-based catalysts with specific morphology become a hot research topic.To meet this goal,two kinds of Pt-based alloy catalysts have been successfully synthesized.They exhibited superior performance towards small molecule oxidation reaction in anode and oxygen reduction reaction in cathode,respectively.Related contents are summarized as follows:(1)We developed a facile one-step solvent thermal method to successfully synthesize hexagonal PtBi nanoplates with edge length of 36.9 nm and thickness of 19.5 nm.XRD and HRTEM confirmed that the as-prepared PtBi nanoplates are intermetallic.The PtBi/C catalyst exhibits superior electrocatalytic activity towards formic acid oxidation reaction(FAOR)and the mass activity reaches 9.06 A mgpt-1,which is 10.4 times higher than commercial Pt/C catalyst and it’s the highest electrocatalytic activity ever reported.In situ FTIR spectra revealed that the indirect dehydration route is totally suppressed on PtBi/C catalysts.For glycerol oxidation reaction(GOR),the PtBi/C features a mass activity of 3.45 A mgpt-1,which is 3.2 times higher than that of commercial Pt/C catalyst.The products were analyzed by in situ FTIR spectra and the reaction mechanism were proposed on PtBi/C and commercial Pt/C catalysts.(2)We developed a simple solvent thermal method to successfully synthesize octahedral PtCu alloy nanocrystals with edge length of 15 nm.The as-prepared octahedral PtCu/C catalyst shows excellent electrocatalytic activity towards oxygen reduction reaction(ORR).The specific activity and mass activity of the synthesized octahedral PtCu/C reach 3.29 mA cm-2 and 1.12 A mgPt-1 at 0.90 V(vs RHE),respectively,which are 17.3 and 7.5 times higher than those of commercial Pt/C catalyst.The mass activity loss of octahedral PtCu/C is 40%after 10,000 potential cycles.In order to further improve the stability of the catalyst,we synthesized octahedral PtCuRh0.05 alloy nanocrystals.The morphology and particle size of PtCuRh0.05 nanocrystals are consisitent with octahedral PtCu nanocrystals.Compared with octahedral PtCu/C,the electrocatalytic activity of octahedral PtCuRh0.05/C decreases slightly,while the stability of octahedral PtCuRh0.05/C is greatly improved.The mass activity of octahedral PtCuRh0.05/C decreases by only 9%after 10,000 potential cycles.Further characterization revealed that the introduction of Rh can inhibit the migration of Pt and the dissolution of Cu,and maintain the(111)facets with high oxygen reduction activity.