Preparation Of Tantalum-based Composite Catalyst And Its Electrocatalytic Performance In Alkaline Media

Energy issues have always been the focus of global attention,and the solutions of these problems depend on the development of chemical fuels.Direct alcohol fuel cells?DAFCs?use small molecular alcohols as fuel to convert chemical energy into electrical energy directly.At the same time,they have the advantages of high energy conversion efficiency,low environmental pollution caused by products,safer storage and transportation,low cost,and high availability.And they have received widespread attention.However,electrode materials are easily poisoned by carbon-containing toxic intermediates such as CO generated during the oxidation of alcohols,which will reduce the electrocatalytic activity.Traditional DMFCs usually use the most efficient and stable Pt-based catalysts.However,Pt is not suitable for large-scale commercialization because of its high cost and poor resistance to CO poisoning.In order to improve these defects,a series of Ta-based catalysts were synthesized starting from the preparation of high-efficiency catalysts.As anode oxidation catalysts using methanol,ethanol,and ethylene glycol as fuels,they were:TaC-TaN-Ta₂O₅ homogeneous three-phase composite Catalyst,TaC-TaN composite supported Pd nanoparticles?Pd/TaC-TaN?,TaON supported Pd nanoparticles?Pd/TaON?and Ta₃N₅ supported Pd nanoparticles?Pd/Ta₃N₅?.The research contents include the following:?1?A calcination method was used to synthesize TaC-TaN-Ta₂O₅ homogeneous three-phase composite catalysts,and R=3-12 series catalysts are synthesized according to different feed ratios of the raw materials.Show a certain law,and use XRD,SEM,TEM,XPS,etc.for characterization and analysis,and found that the TaC-TaN-Ta₂O₅ series catalysts have a certain law with the increase of the feed ratio,TaC and TaN phases always exist,and Ta₂O₅ phase appears first appeared and then disappeared.The surface of the TaC-TaN-Ta₂O₅ series catalyst has a wrinkle appearance,and has a large specific surface area covered by a carbon film.At the same time,the catalyst has good stability.?2?Change the raw material ratio to 13:1,the TaC-TaN composite is synthesized in one step by using a lower calcination temperature.The sheet-shaped TaC-TaN has a larger specific surface area under the encapsulation of the carbon layer.The Pd nanoparticles are supported on the TaC-TaN composite by a simple method.?Pd/TaC-TaN?,this chapter not only explores the optimal loading of Pd,but also compares its performance with commercial catalysts.It has proved that the high-efficiency catalyst has long-term stability,high resistance to toxicity,and superior electron transfer capabilities.It has excellent catalytic activity for alcohol oxidation reaction in alkaline solution.At the same time,it has surpassed the commercial catalysts Pd/TaC and Pd/TaN,and its methanol forward scanning oxidation peak reached 396.8 mA·mg^-1Pd,which was 5 times that of commercial Pd?10%?/C.?3?Further increase the ratio of raw materials to 30:1,the Ta₂O₅ catalyst was synthesized by low-temperature calcination,and N was doped by NH₃ calcination to synthesize a series of catalysts such as TaON and Ta₃N₅,and Pd nanoparticles were supported on the catalyst to obtain Pd/TaON and Pd/Ta₃N₅ catalysts.SEM and TEM showed that the particle size of TaON and Ta₃N₅ gradually became uniform,and both had carbon wrinkles can increase specific surface area.CV,It,EIS and other tests have shown that Pd/Ta3N5 has good electrochemical properties,its methanol forward scanning oxidation peak reaches 722.2 mA·mg^-1Pd,ethanol forward scanning oxidation peak reaches 851.9 mA·mg^-1Pd,ethylene glycol positive The oxidized peak of the directional scan reaches 809.2 mA·mg^-1Pd,far exceeding the commercial Pd?10%?/C.It has the advantages of good electrocatalytic effect,strong stability,strong resistance to CO poisoning,and small surface electron transfer resistance.The electrocatalytic performance of Pd/TaON is second only to Pd/Ta₃N₅.