The Research Of Palladium-based Catalytic Materials For Oxidation Of Formic Acid, Ethanol And For Reduction Of Oxygen

Fuel cells have roused a widespread attention,for their high energy efficiency,high energy conversion and low pollution.Until now,there are a lot of researches focused on improving the catalytical performance of electrocatalysts to expand the use of the fuel cell.The performance of the catalysts is usually depenond on the component and structure of the catalysts and the characteristic of their supportting.This article is mainly for exploring the components and preparation methods of the palladium alloy catalysts of electrodes.Here,a series of carbon support PdCuO,PdWO,and Pd decorated Cu catalysts are prepared.We studied the properties of PdCuO/C catalysts for ethanol oxidation,carbon loaded PdWO catalysts for oxygen reduction reaction and carbon support Pd decorated Cu catalysts for formic acid oxidation,respectively.The physical properties of the catalysts were characterized by X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),transmission electron microscopy(TEM),energy dispersive spectroscopy(EDS)and inductively coupled plasma-atomic emission spectrometer(ICP-AES).The electrochemical performence of the catalysts were tested by cyclic voltammetry(CV),linear sweep voltammetry(LSV)and chronoamperometry(CA)method.The main results of this paper are as follows:1.A series of oxidiferous PdCu/C nanoparticles have been prepared by the NaBH4 reduction method.Among them,oxidiferous Pd0.9Cu0.1/C(Pd:Cu=9:1,metal atomic ratio)exhibits the highest electrocatalytic activity for ethanol oxidation reaction(EOR)in alkaline media.The onset potential of oxidiferous Pd0.9Cu0.1/C is negatively shifted 150 mV compared to Pd/C,and the peak current density is twice than that of the Pd/C catalyst.The oxidiferous Pd0.9Cu0.1/C also exhibited high stability and poisoning tolerance,which indicated that it is a good candidate for the anode of direct ethanol fuel cells(DEFCs).2.We prepared a series of oxides containing PdW/C catalysts by the NaBH4 reduction method.Among them,oxides containing Pd0.8W0.2/C(Pd/W = 8:2,atomic ratio)exhibits the highest electrocatalytic activity for oxygen reduction reaction(ORR)in alkaline media.Oxides containing Pd0.8W0.2/C with an onset potential 0.092 V vs Hg/HgO is positive shift 157 mV compared to Pd/C(-0.065 V vs Hg/HgO).The peak current density of oxides containing Pd0.8W0.2/C is more than twice of the peak current density of Pd/C.Oxides containing Pd0.8W0.2/C also exhibited high stability and tolerance to methanol,which indicated that it is a good candidate for the cathode electrocatalyst for ORR.3.We prepared Pd decorated Cu catalysts by sculpturing Cu template and studied the catalytic activity of Pd decorated Cu/C catalysts prepared by different etching time for formic acid oxidation.The results show that Pd decorated Cu/C-3 catalysts etched 3 hours in 0.2 M PdCl2 solution have the best electrocatalytic activity for formic acid oxidation.