Preparation And Performance Study Of Pt-Based Multicomponent Catalysts For Direct Methanol Fuel Cells

The fuel cell is the fourth generation power generation technology after thermal power,hydropower and nuclear power.It is a device that directly converts chemical energy into electrical energy through an electrochemical reaction process.The direct methanol fuel cell is a kind of low-temperature fuel cell,which has the advantages of high energy conversion density,environment friendly,and easy construction,and has been widely concerned.However,electrocatalysts are one of the most important materials for forming direct methanol fuel cells.Fuel cell performance is poor due to poor catalytic activity of the electrocatalyst,low platinum utilization,and poor resistance to CO poisoning.Therefore,improving the activity,stability and anti-CO poisoning ability of direct methanol fuel cell catalysts has become a research hotspot in the field of fuel cells.We are committed to the synthesis of a new direct methanol fuel cell anode multi-component platinum-based catalyst to promote the commercialization of direct methanol fuel cells.This paper studied three kinds of direct methanol fuel cell anode multi-component platinum-based catalyst materials,summarized as follows:First,a one-step templateless solvothermal method was used to synthesize platinum-copper alloy nanowires in order to improve its electrocatalytic activity,platinum utilization rate and CO poisoning resistance.The synthesis conditions were studied to comprehensively control the composition,morphology,size and phase structure of Pt_xCu_y alloy nanowires.The catalytic activity of Pt_xCu_y alloy nanowires for methanol oxidation was also investigated.XRD showed that the Pt₂₀Cu₈₀ alloy nanowires were face-centered cubic and formed an alloy structure.The TEM showed that the single Pt₂₀Cu₈₀ alloy has a nanowire diameter of 1.4±0.5nm,and the wire harness is composed of a plurality of nanowires with a wire diameter of15±10 nm.The mass current density of Pt₂₀Cu₈₀ alloy nanowires for methanol oxidation reached 686.2 mA·mg^-1,which is 3.3 times of 20%Pt/C commercial catalyst,and showed excellent stability and CO poisoning resistance.In the methanol oxidation reaction,the alloy nanowire structure and the synergistic effect of PtCu promotes the transfer of CO poisons on Pt to Cu,which fully exposes the active sites on the surface of Pt and improves its catalytic performance.Secondly,a one-step templateless solvothermal method was used to synthesize platinum-copper-nickel nanowires.The purpose was to increase the electrocatalytic activity,Pt utilization rate and CO poisoning resistance based on the platinum-copper alloy nanowires.The synthesis conditions and morphology of Pt_xCu_yNi_z NWs were studied.The TEM showed that the fine particles adhered more uniformly to the surface of Pt_xCu_yNi_z NWs,hindering the binding combination of multiple individual nanowires,resulting in an ultra-long ultra-fine Pt₃₀Cu₃₇Ni₃₃ NWs with a length of 4.4?m and a wire diameter of 16±8 nm,and an ultra-long ultra-fine Pt₁₈Cu₂₂Ni₆₀ NWs with a length of 4.4?m and a wire diameter of 10.6±6.4 nm.In addition to lowering the Pt loading and better methanol oxidation performance,the CO oxidation peak position of Pt₃₀Cu₃₇Ni₃₃ and Pt₁₈Cu₂₂Ni₆₀ catalysts was 0.52V,which showed a better anti-CO poisoning performance than the 20%Pt/C commercial catalyst with a negative shift of 80 mV.Thirdly,the acid-treated CNTs were used as the carrier,and the monothiol-protected Au-MPA nanoclusters prepared by the immersion reduction method were used as the core,and the low-platinum core-shell catalyst of Au-MPA/CNTs@Pt was prepared by pulse electrodeposition.Its electrocatalytic activity,methanol oxidation activity and stability were explored.The TEM showed that the average particle diameter of Au-MPA in Au-MPA/CNTs?20?was 1.15±0.25 nm,and the dispersibility was good.The ECSA value of Au-MPA/CNTs@Pt?x?is close to that of the 20%Pt/C catalyst.Accelerated stability tests?1000and 2000 cycles of cyclic voltammetric curve scanning?of Au-MPA/CNTs?20?show that it retains 91.7%and 109.6%of its initial ECSA,which is much more stable than that of 20%Pt/C catalyst.It shows that pulse electrodeposition is an effective way to improve the utilization of platinum and the catalyst has high catalytic stability.