Morphology Control Synthesis And Anode Electrocatalysis Performance Of Pt/Pd-based Catalysts For Fuel Cell

Catalyst is one of the most key components for fuel cell power, the catalyst technology's breakthrough seriously affected the smooth implementation of fuel cell commercialization. In this paper, beginning with the morphology and composition of the catalyst material, three different fuel cell anode catalysts with different morphology and composition were prepared through the method of electrodeposition:nanoporous PdNi alloy nanowires,PtCu alloy nanotubes and spherical PdNi2 alloy. Their physical properties and catalytic activities were tested by means of certain physical and electrochemical methods.By dealloying with electrodeposited Ni-rich Pd75Ni25 alloy nanowires, nanoporous Pd53Ni47 alloy nanowires was prepared. XRD shows nanoporous Pd53Ni47 alloy nanowires have the same crystal structure with pure Pd. TEM shows the nano-hole diameter on the nanowires is about 3-6nm, the metal lattice size is about 4-7nm. The electrochemical tests show that the nanoporous Pd53Ni47 alloy nanowires have larger electrochemical active surface area compared with 20% Pd/C catalyst, and it's catalytic activities and stability towards formic acid electrooxidation are also better than 20% Pd/C catalyst. The peak current density of formic acid electrooxidation on nanoporous Pd53Ni47 alloy nanowires was up to 820mA/mg-1Pd, for 20% Pd/C catalyst, the corresponding number was 700mA/mg-1 Pd, the catalytic activity was promotioned by 20%.PtCu alloy nanotubes was prepared through the replacement reaction between the electrodeposited Cu nanowires and H2PtCl6 solution. During the replacement reaction, the stabilizing agent's existence or not,the amount of noble metal salt solution and the subsequent treating play an important role on the morphology and composition of the nanotube. SEM shows that the material has good nanotube morphology, with the length about 1-2um, the diameter about 250nm, and the wall thickness about 5nm, EDS shows that the Pt and Cu atomic ratio in PtCu alloy nanotubes is 68:32. The electrochemical tests show that although PtCu alloy nanotubes has mucher smaller electrochemical active surface area than 20% Pt/C catalyst, on unit active area, the catalytic activities towards the electrooxidation of all methanol,formic acid and dimethyl ether are much better, the PtCu alloy nanotubes also have good ageing resistance performance.In the experiment, spherical PdNi2 alloy was also prepared directly on glassy carbon electrode through the method of constant-current electrodeposition. Physical characterization show that with Ni alloying, the shape of PdNi2 particles was changed to uniform spheres from complex polyhedrons, and it has the crystal structure of Ni. The electrochemical tests show that although the Pd content in PdNi2 alloy is much fewer, the molar ratio was only one third of pure Pd, but because of the dope of Ni, the peak current density of formic acid electrooxidation on PdNi2 alloy was up to 23mA/cm2, for pure Pd, the corresponding number was 8mA/cm2, the catalytic activity was promotioned by about three times. The result of chronoamperometry tests show that the stability of PdNi2 alloy is also apparently better than pure Pd.