Construction Of Electrochemical Interface Of Ta-based Nanomaterials And Research On Its Electrochemical Properties

At present,there are more and more researches on direct methanol fuel cells?DMFC?and lithium ion batteries?LIBs?in the world.For methanol as a fuel,the device and structure are simple,high energy density,low operating temperature,and convenient storage.As a new type of device that converts chemical energy into electrical energy,DMFC has a good application prospect in the field of power batteries of new energy vehicles.At the same time,LIBs have long cycle life,high specific energy,wide operating temperature range,high environmental performance and many other advantages,making lithium batteries the main reason for powering electric vehicles.There are already commercial catalysts for these two kinds of battery materials on the market,but still have some problems,such as higher cost,poor stability,and environmental pollution.In this paper,three kinds of Ta-based catalysts were designed and applied in methanol fuel cells and lithium ion batteries respectively.The structural of these materials were discussed,and the performance differences were analyzed and explained.The following are the main research contents:1.Pt/WO₃-NaTaO₃ composite catalyst with different W/Ta molar ratios were obtained via a facile hydrothermal method.WO₃-NaTaO₃heterojuction was constituted and could be regulated by the adjustment of W:Ta ratio,as confirmed by multiple characterizations.Due to the favorable CO anti-poisoning ascribed to the enough surface-OH_add provided by both WO₃ and NaTaO₃,the excellent stability in acid and alkali for WO₃-NaTaO₃ composite,and charge transfer from metal oxide to Pt,as-obtained Pt/WO₃-NaTaO₃ composite catalyst might exhibit desirable high electrocatalytic performances.As a result,the as-prepared Pt/WO₃-NaTaO₃?W:Ta=3:1?and Pt/WO₃-NaTaO₃?W:Ta=0.2:1?showed the optimal performance in MOR process in acid and alkali,respectively,as compared with commercial Pt/C,Pt/NaTaO₃ and Pt/WO₃ catalysts.In addition,the density functional theory calculations further proved the promotion effect of WO₃ on methanol electro-oxidation..2.The poor durability of commercial Pt/C catalyst in the process of alcohols electrocatalytic oxidation is mainly due to the weak corrosion resistance of carrier carbon to acid and alkali,and the inadequate grasp ability of carbon supporter to Pt nanoparticles leads to the exfliation and aggregation of Pt.Herein,sodium tantalate,such as NaTaO₃ and Na₂Ta₂O₆,with strong stability to acid and base was introduced as carrier material of Pt catalyst.Various characterization approaches indicate that Pt nanoparticles exhibit exceptionally high monodispersity on the surface of sodium tantalum,especially Na₂Ta₂O₆,and strong interaction with sodium tantalate.The catalyst of Pt/Na₂Ta₂O₆ exhibits high electro-catalytic activity towards methanol and ethanol oxidation reaction.More prominent is that Pt/sodium tantalate catalysts prove to be high-durability for methanol and ethanol electro-oxidation.3.Owing to LIBs are widely used in portable electronic devices due to their high energy density,long cycle life and no memory effect.Here,we describe the preparation of carbon-coated TiO₂ and rGO are uniformly compounded as an electrode material and explored the impact of materials with different sizes on battery performance.The well-structured materials TiO₂-C-rGO,with high specific surface area?134.72 m²/g?,deliver a high capacity(⁸34 mAh g^-1 at the end of 300 cycles at 0.1A g^-1),a high specific capacity of³89 mAh g^-1 can be achieved up to 600 cycles at a current density of 5A g^-1.These excellent charateristics arise from the TiO₂-C-rGO novel structured,the uniform carbon layer increases the conductivity of TiO₂,and inhibiting the transformation of TiO₂ from anatase to rutile phase at high temperature.Two kinds of materials,Ta₂O₅ and Ta₂O₅/C,were synthesized by high temperature calcination and hydrothermal method as anode materials of lithium-ion batteries.The results showed that Ta₂O₅/C has the highest battery capacity,cycle stability and rate performance.