The Structure Design And Synthesis Of RuO₂-based Composites And Their Electrochemical Performance For Supercapacitor

With the development of society and the improvement of living standards,the requirements for clean and efficient energy are constantly increasing.As a kind of clean,efficient and safe energy storage device,supercapacitors have attracted a lot of researches and attention.The key factor influencing the performance of supercapacitors is electrode materials.Oxide electrode materials have attracted more and more attention due to their high theoretical specific capacity and friendly environment.However,most of the oxide materials have the problems of large electron transport resistance and low specific surface area,and the high cost of the yttrium oxide material with excellent performance needs to be solved.The design of nanostructures for transition metal oxides,such as clustering of oxides,hollowing out and recombining heterogeneously,is important idea for solving the above problems.The specific research content and results of this paper are as follows:(1)Using redox method and RuCl3 and NaBH4 as raw materials,Ru02/rG0 composites with specific surface area of 158 m2·g-1 can be obtained by controlling the pH of the reaction system,carbon material adsorption and heat treatment.The effect of the pH value of the reaction system on the cluster particles is investigated.The size of the cluster particles rapidly increases with the increase of the pH value.When the pH value is 4.9,the Ru cluster particles with an average size of 1.7 nm prepared,which can be stably dispersed in the aqueous phase.At the same time,the influence of different carbon matrix on the electrochemical performance of Ru02 cluster particles is investigated.The result shows that Ru02 cluster materials loaded on different carbon substrates have higher specific capacities and lower resistance values than commercial Ru02/C.Besides,It is observed that Ru02·xH20/rG0 nanocomposites have the best electrochemical performance and the specific capacity reaches 1099 F·g-1.(2)The core-shell Ag/Ru nanoparticles are prepared by the oleylamine reduction method using silver core as the template,and the hollow structure Ru02/C composite materials with the wall thickness of about 2 nm prepared by using the self-diffusion mechanism of polycrystalline silver and the heat treatment process.The influences of hollow structure and core-shell composites on the electrochemical properties of oxide materials are compared and analyzed.The result shows that the hollow structure provides more electrochemical active sites for electrochemical reactions,shortens the ion diffusion distance,and reduces the electrodes impedance,so hollow structure RuO2/C composite material has higher specific capacity than core-shell structure Ag/RuO2/C composite and its specific capacity reaches 805.8 F·g-1.(3)A transition metal core used as a template instead of a silver core,Cu0/Ru02 composites nanoparticles with a hollow structure are synthesized using a seed growth method,an oleylamine reduction method and a heat treatment process in order to reduce the amount of Ru02 and the cost of materials.The formation mechanism of the hollow structural material is investigated.The result shows that the hollow structure is formed by the bimetallic diffusion process.Other transition metal core systems are also explored and found that the preparation method can be extended to cobalt,nickel,copper nickel and other hollow composite oxides.In addition,the effect of different composite oxides on the electrochemical performance of the material is examined.The result shows that the specific capacity of NiO/RuO2/C material with an RuO2 content of 19.6 wt%is 907.3 F g-1,which is better than commercial RuO2/C composites.(4)A CuO/Pt nanocomposite with a hollow dodecahedron frame structure is designed by using the method of bimetallic diffusion and oxygen etching.The mechanism of formation of hollow dodecahedron structure is investigated.The effects of different structures on the specific surface area and conductivity of nanomaterials are compared and analyzed.The result shows that compared with the core-shell materials,the hollow structure increases the specific surface area of CuO/Pt nanomaterials to 122.5 m2·g-1.The influence of different structures on the electrochemical properties of nanomaterials is investigated.It is found that the hollow structure CuO/Pt has higher capacity,lower resistance and better rate performance.Moreover,AC impedance analysis result shows that the microporous electrode diffusion effect is beneficial to the improvement of the specific capacity of the material.