Controlled Synthesis Of Tantalum-based Materials And Study On Electrocatalytic Properties For Small-molecule Alcohol Oxidation

Direct Alcohol Fuel Cells?DAFCs?are electrochemical devices that they directly convert the chemical energy of fuels into electrical energy without combustion,which has minimal environmental impact.In addition,they have high energy conversion efficiency due to having no restricting by the Carnot cycle.Therefore,DAFCs are significant in solving environmental pollution and energy shortage problems.During the DAFCs development process,the low activity of catalyst was the one of the serious problems.At present,Pt and Pt-base materials were used toward the alcohol oxidation in anode of DAFCs.However,Pt is easily poisoned by adsorbed CO,an intermediate of alcohol oxidation,then reduced the utilization of DAFCs catalysts.Therefore,the study on the high efficiency and low cost catalyst is an important way to reduce the cost and promote the commercialization of fuel cells.This work studied a series of Ta-based catalystic materials?Pd loaded Ta₂O₅?Pd/Ta₂O₅?,reduced graphene oxide-Ta₂O₅ supported Pd nanoparticles?Pd/Ta₂O₅-RGO?,iron tantalate with N-ferriccarbide?FeTa₂O₆-Fe₃C-N??toward the electrooxidation of methanol,ethanol and ethylene glycol.The electrocatalytic activity and durability of Ta-based catalysts with loaded and composite were enhanced.The research work contains several aspects as following:?1?Pd loaded Ta₂O₅?Pd/Ta₂O₅?particles were prepared by reflux method.The crystal structures and morphology of samples were characterized with X-ray diffraction?XRD?,scanning electron microscopy?SEM?,transmission electron microscopy?TEM?and high resolution TEM?HRTEM?.The cyclic voltammetry?CV?,chronoamperometry?I-t?,and electrochemical impedance spectroscopy?EIS?were carried out on an electrochemical workstation under acid condition.The result implied that the Pd/Ta₂O₅ catalyst had high catalytic activity for methanol,ethanol and ethylene glycol oxidation in acid medium.?2?Based on the study of Pd/Ta₂O₅,we chose graphene?RGO?used as the support.The Pd/Ta₂O₅-RGO particles were synthesized by reflux method.The crystal structure and morphology of the samples were characterized with XRD,SEM,and TEM?including HRTEM?.The state of Pd loading on the Ta₂O₅ surface was determined by X-ray photoelectron spectroscopy?XPS?.The results showed that the conductivity enhanced,specific area enlarge and active site increased of Pd/Ta₂O₅ after it was added into graphene.The electrocatalytic activity and stability of Pd/Ta₂O₅-RGO particles were better than that of commercial platinum carbon?Pt/C 10%?under alkaline condition.?3?The composite catalyst FeTa₂O₆-Fe₃C-N was prepared by one step-calcination method.Different molar compound ratios of FeTa₂O₆ and Fe₃C-N catalysts were studied.The results showed that electrocatalytic activity of composites was obviously better than that of single phase.The optimal molar ratio of the FeTa₂O₆ and Fe₃C-N was 1:2.The electrocatalytic activity of the sample toward ethanol oxidation was close to the commercial Pt/C?10%?.It is expected that FeTa₂O₆-Fe₃C-N has high electrocatalytic activity toward alcohols oxidation as a non-noble metal catalyst.