Synthesis And Characterization Of Cathode Electrocatalyst For Proton Exchange Membrane Fuel Cell

In recent years, the cathode electrocatalyst of proton exchangemembrane fuel cells （PEMFC） has become the research focus for thenational research workers, but the high price and low catalysis activitymake PEMFC commercial difficultly, limiting the further development ofPEMFC. In this paper, the novel core-shell electrocatalysts which aresynthesized by transition metals （Cu, Ag） as the core, Pt as the shell,multi-walled carbon nanotubes（MWCNTs） as the supporter are prepared,and different MnO₂crystal structures were doped into the core-shellelectrocatalysts. Using FT-IR, XRD, HRTEM, SEM, XPS, CV, i-t, LSV,EIS and other various characterizations to measure the electrocatalysts,aimed at to prepare the cathode catalyst with high catalytic activity, highPt utilization and low cost compare with pure Pt electrocatalysts. Moredetails are presented as following: Pt/MWCNTs, Cu@Pt/MWCNTs, Ag@Pt/MWCNTs electrocatalystswith low and high Pt loading were synthesized by chemical reductionmethod，and optimizing the preparation conditions and the metal ratio ofcatalyst. Using a variety of characterization methods proved thecore-shell electrocatalysts with small particle size, uniform dispersionwere prepared, which have excellent electrochemical properties of thelarge electrochemical active area and the good oxygen reduction ability.The largest electrochemical active area of all prepared electrocatalyst is73.4m2g-1, which is twice as large as the commercialization catalyst（JM）, at the same time, the content of noble metal Pt were less thancommercial catalysts.Two crystal of MnO₂（α-MnO₂, β-MnO₂） were synthesized byhydrothermal method, and then doped into the Cu@Pt/MWCNT andAg@Pt/MWCNTs core-shell electrocatalysts. A variety ofcharacterization methods prove the formation of α-MnO₂, β-MnO₂, andelectrochemical characterization results imply the core-shellelectrocatalysts with β-MnO₂doped have a large electrochemical activearea, high stable current and oxygen reduction onset potential. The largestelectrochemical active area of all prepared electrocatalyst is122.8m2g-1,which increase significantly relative commercial catalysts.Simultaneously, the catalytic mechanism of the electrocatalystsmentioned are studied and analyzed preliminary.