Preparation And Electrocatalytic Performance Of LDHs Supported Pd-based Catalysts

In recent years,direct ethanol fuel cells?DEFC?have been widely concerned for their potential energy and power density.The anode catalyst is a key factor in determining the performance and cost of DEFC.Pd-based catalysts have been widely studied for their relatively low price and high electrocatalytic activity in alkaline media compared to Pt-based catalysts.However,their activity and stability still cannot meet commercial application.Adjusting the morphology and electronic structure of the catalyst is an effective strategy to improve the catalytic performance of catalyst.In addition,anchoring the catalyst to a suitable carrier can improve the stability and utilization and enhance the activity of the catalyst.Layered double hydroxides?LDHs?have been widely concerned because of their typical layered structure and excellent physicochemical properties.Based on these,supported Pd-based catalysts were prepared by using LDHs as the carrier,and their electrocatalytic oxidation of ethanol was studied.The main achievements are as follows:?1?The three-dimensional flower-like NiAl-LDH was prepared by solvent heat method.And the Pd-based catalyst was prepared by simple electrodeposition method using the prepared NiAl-LDH as the carrier.Ni:Al feed ratio and urea content in the experiment had important effects on the structure and morphology of NiAl-LDH.The electrochemical characterization results showed that Pd alloyed with Au and the carrier of NiAl-LDH had positive effects on improving the performance of Pd-based catalyst for the electrocatalytic oxidation of ethanol.?2?The NiMgAl-LDH was prepared by urea hydrolysis method,and using it as the carrier,Pd-based nanowire catalysts supported on the layered surface of NiMgAl-LDH were successfully prepared under the condition of stirring at room temperature by changing the adding order of precursors and reducing agents.Electrochemical characterization showed that the AuPd NWs/LDH catalyst prepared in this study showed the highest catalytic activity(2927mA mg_pd^-1)for the electrocatalytic oxidation of ethanol in the basic electrolyte,while AgPd NWs/LDH and CuPd NWs/LDH showed better toxicity resistance although their catalytic performance was less.?3?Carbon black and LDH hybridization were used to solve the problem of low conductivity of LDH.On this basis,the AuPd NWs catalyst supported on the surface of layered double hydroxides with carbon black hybrid material was successfully prepared.CB not only improved the conductivity but also promoted the formation of a monodisperse cable-type structure of LDH.,making it more conducive to support of nanowires catalysts.Strong electron interactions between between Au and Pd as well as supporters promoted the absorption of OH radicals and the oxidation of CO intermediates,so as to improve catalytic activity and toxicity resistance.The AuPd NWs/LDH/CB catalysts prepared in this study showed excellent catalytic activity(7090 mA mg_pd^-1).