Preparation Of Cu-based Alloy By Dealloying Method And Its Application In Fuel Cells

With the increasing energy crisis and environmental pollution problems,as a recognized efficient,clean,safe and stable energy conversion technology,fuel cells have attracted more and more attention.The catalytic activity of electrode catalyst on the electrode reaction has a significant impact on the output performance of the fuel cell.The dealloying method has been widely used to prepared metal alloy,it is based on the different activities of metal elements in the alloy,chemical or electrochemical corrosion method has been used to selectively etches the active metal elements with the etching solution.The dealloying method has attracted wide attention of researchers because it is easy to operate and many nanometer-sized metal materials can be obtained by this method.In this paper,Cu-based alloy catalysts has been successfully prepared using one-step dealloying method and these catalysts were applied to the following two aspects:?1?Cu oxide and CuPd alloy oxide nanobelts were used as anode catalyst materials for direct hydrazine/hydrogen peroxide fuel cellsCu,Pd and their oxides have very good catalytic activity to hydrazine oxidation reaction and they can be applied to hydrazine hydrate fuel cells.In this paper,using CuAl and CuPdAl alloys as precursors,Cu oxide and CuPd alloy oxide(CuO?(Cu_0.9Pd_0.1)O)nanobelts were successfully prepared.The electrocatalytic behavior of these two materials for hydrazine was systematically studied,and then they were applicated to direct hydrazine/hydrogen peroxide fuel cells as anode catalysts.The electrochemical test results show that under the same conditions,the hydrazine oxidation current density of Pd added CuO nanobelts was 1.5 times higher than CuO with no Pd element added,which indicated that the Pd added CuO nanobelts has a higher catalystic activity towards hydrazine oxidation reaction.Besides,the stability of Pd added CuO nanobelts has been obviously improved.The power density of direct hydrazine/hydrogen peroxide fuel cells using(Cu_0.9Pd_0.1)O as anode catalyst is 330.5 mW cm^-22 at 80?,which is 100 mW cm^-2 higher than that of CuO(229.3 mW cm^-2).According to the study result of this work and the comparison of the fuel cell performance data in related literatures,the prepared(Cu_0.9Pd_0.1)O exhibits a promising catalystic activity toward hydrazine oxidation reaction.?2?Nanoporous AgCu alloy used as the catalysts towards oxygen reduction reactionAg is a excellent catalyst toward oxygen reduction reaction,and the combination of Ag and Cu elements can adjust their oxygen binding energy??E_o?to a suitable value so their oxygen reduction performance can be enhanced.In this paper,with different proportions of AgCuAl ternary alloys as precursors,three different proportions of nanoporous AgCu alloys were prepared using one-step dealloying method.The catalystic activity of different catalysts towards oxygen reduction reaction was studied.Nanoporous Ag was also prepared as a referenced material by the same method.The results shows that Ag₄Cu exhibited the highest catalystic activity towards oxygen reduction reaction with a onset potential of 0.92 V,a half wave potential of 0.8 V,a limiting diffusion current densities of 5.9 mA cm^-2 and a tafel slope of 77 mV dec^-1.By studied the polarization curves with different rotational speeds,we evaluated electron transfer numbers?n?of oxygen reduction reaction is 3.75 according to Koutecky-Levich equation,which indicated this oxygen reduction reaction is mainly controlled by 4e^-path way.Besides,the methanol tolerance abilitiy and the stability of Ag₄Cu in alkaline condition is better than that of commercial Pt/C catalyst,which indicated that Ag₄Cu is a promising catalyst towards oxygen reduction reaction.