Preparation And Electrocatalytic Characteristics Research Of Pd-based Catalyst For Ethanol Electro-oxidation

Direct ethanol fuel cell (DEFC) is a power generating device which directlychanges the chemical energy of ethanol with oxygen into the electrical energy.Ethanol is a most promising substitute methanol because of its rich, lowtoxicity and higher hydrogen content. It is very great significance to studydirect ethanol fuel cell to solve the energy shortage and environmentalprotection.In this study, Pd-based catalyst was used as the anode catalyst in thepreparation of high activity, stability and good performance of the Pd-basednano-catalyst. The metal particle size, morphology, electrochemical activity andstability of carbon supported Pd and Pd alloy catalysts were investigated. Themain contents and results are as follows:Using Vulcan XC-72as supports and sodium citrate as a stabilizer,20wt%carbon supported PdC-B and PdC-P catalysts were prepared by impregnatingreduction method with using NaBH4and NaH2PO2as reductants, respectively.TEM, XRD and EDS were applied for characterizing catalysts. Catalyticactivity and stability were studied in ethanol solution and the method ofpre-adsorbed CO monolayer stripping was used to research their anti-poisoningability. The results showed that the average diameter of PdC-B catalyst is 3.3nm, smaller than that of PdC-P with38.0nm. The electrochemical testsresults indicate that the onset potential (Eonset) of PdC-B is-0.54V, which havenegatively shifts by~30mV as compared to that of PdC-P (-0.51V). On thatbasis,20wt%carbon supported PdNi and PdCo catalysts were prepared usingNaBH4as reductant. The results showed that the average diameter of PdCocatalyst is2.9nm, the peak current intensity (jp) is51.75mA·cm-2, higher thanthat of commercial PdC(Johnson Matthey) catalyst (48.70mA·cm-2), showed abetter catalytic activity.20wt%carbon supported PdMg catalysts with different ratios wereprepared by ethylene glycol method. TEM, XRD and EDS were applied forcharacterizing catalysts. Catalytic activity and stability were studied usingcyclic voltammetry method in ethanol solution. The results showed that whenthe ratio of Pd and Mg was3:2, the average diameter of PdMg catalyst is3.1nm,the jpis51.75mA·cm-2at-0.25V, much more higher than that of PdC(JohnsonMatthey)(48.70mA·cm-2). The PdMg (3:2) showed the better activity andstability.20wt%carbon supported PdW catalysts with different ratios wereprepared by ethylene glycol method. TEM, XRD and EDS were applied forcharacterizing catalysts. Catalytic activity and stability were studied usingcyclic voltammetry method in ethanol solution. The results showed that whenthe ratio of Pd and W was1:1, the average diameter of PdMg catalyst is3.6nm,the jpis62.29mA·cm-2at-0.27V, higher than that of PdC (Johnson Matthey) (48.70mA·cm-2). The PdW (1:1) showed the better activity and stability.20wt%carbon supported PdNiW and PdNiMo catalysts with wereprepared by impregnating reduction method with using NaBH4and ethyleneglycol as reductants. The results showed that the average diameters of PdNiWand PdNiMo are4.2and3.9nm, the jpof both catalysts are higher than that ofPdC (Johnson Matthey) catalysts. The catalysts showed higher activity toethanol.