Preparation Of Multiple Pt-Based Nanocatalysts And Its Methanol Electrocatalytic Performance

To address the growing energy demand and global environmental pollution problems,the researchers are committed to developing and utilizing clean and pollution-free new energy sources.As a sustainable new energy source,fuel cell is the focus of the current research,which has the advantages of small volume,high energy conversion rate,high energy density and environmental friendliness.As an easily accessible fuel,methanol is easy to storage and transportation,and will not cause damage to the environment,it is an important energy source for sustainable utilization.Therefore,direct methanol fuel cells(Direct Methanol Fuel Cells,DMFCs)is considered as an efficient and environmentally friendly energy power generation technology and has good development prospects.Pt-based catalyst is the most widely used anode catalyst of DMFCs at present,but the high price and small reserves of precious metal Pt,COads and other intermediates can easily cause catalyst poisoning problems limit its large-scale use.Therefore,the development of new methanol fuel cell anode catalyst is a hot research direction.In this paper,the new multi-element Pt-based alloy nano-catalyst was prepared by direct grinding method and co-reduction method.The electrochemical properties of the catalyst were tested under acidic methanol conditions,and the morphology,crystal structure,atomic valence state and electronic structure of catalyst were characterized by TEM,XRD and XPS techniques to clarify action mechanism of the catalyst.The experimental results show that the electrochemical properties of the catalyst prepared by co-reduction method are greatly improved,and they show excellent electrocatalytic activity and cycle stability for methanol oxidation.The main study results are as follows:(1)The PtRuCe alloy nanoparticles(NPs)catalysts were prepared by direct grinding method.The experimental results showed that the PtRuCe alloy nanoparticle catalysts showed the best methanol electrocatalytic oxidation performance under the condition of added 2 g Dicyandiamide,heat treatment temperature at 700 ℃,the metal Pt loading rate of 20%,and the organic solution of Ce was used as the metal precursor;(2)The PtRu binary alloy nanowires(NWs)catalysts were prepared by co-reduction method.The experimental results show that the catalyst has the optimal peak current density of methanol oxidation at heat treatment temperature of 400 ℃and the Pt-Ru atomic ratio is 1:1,the peak current density up to 825.3 m A/mg Pt,it is5.3 times that of PtRuCe alloy nanoparticle catalyst.After the i-t stability test,the PtRu nanowire catalyst of 400 ℃ had the slowest current decay,indicating the optimal stability;(3)PtRuNi ternary alloy nanocatalysts was prepared based on the PtRu binary catalyst.The experimental results showed that the onset potential of methanol oxidation of PtRuNi catalyst is about 0.36 V,which indicates that the addition of Ni reduces the overoxidation potential of methanol,which is conducive to the catalytic oxidation of methanol.Compared with PtRu NWs/C,the electrochemical activity of PtRuNi NWs/C improved significantly.At the heat treatment temperature of 400 ℃,the mass activity of PtRuNi NWs/C for methanol oxidation in acidic electrolyte reached 1231.58 m A/mg Pt.The PtRuNi NWs/C showed the optimal stability by i-t test and showed a good resistance to CO poisoning through the CO-stripping test.The synergy between PtRuNi enhances the catalytic properties of Pt-based catalysts,and the addition of Ru and Ni elements reduces the binding energy of Pt,which will weaken the adsorption of COads poisoning species on the surface of Pt-based catalysts,and contribute to promote the electrocatalytic properties of methanol oxidation through the ligand effect;(4)Compared with the electrochemical activity of Pt,PtRu,and PtRuNi nanowire catalysts after 400℃ heat treatment and commercial Pt / C catalyst,PtRuNi ternary electrocatalyst has optimal methanol oxidation activity and stability,and the mass activity is much higher than that of Pt catalyst and PtRu binary alloy catalyst,1.5 times that of PtRu catalyst,and 2.1 times higher than that of commercial Pt/C catalyst,indicating that the addition of Ni element has significantly improved the performance of PtRu NWs/C catalyst.