Preparation And Properties Of Carbon Nanotube Based Multifunctional Composites Modified By Phosphonic Acid

Carbon nanotubes（CNTs）have great electrochemical,thermodynamic and mechanical properties due to their special structures such as large specific surface area and tubular structure with voids in the middle,and its use in many aspects is also very common and has received attention from experts in China and abroad.Organic phosphonic acid has many groups that can bond with metal ions,such as amino and phosphonic acid groups.As one of the recognized green energy sources,hydrogen energy has many advantages.Hydrogen storage by electrochemical method is considered to be one of the best energy storage systems.In this paper,based on the research of the group,the multifunctional composites were prepared by modifying the carbon nanotube matrix materials with different kinds of phosphonic acids and compounding with other materials respectively,and their application prospects in the field of adsorption of heavy metals,supercapacitor materials and hydrogen storage were investigated.1.An organophosphonic acid modified multi-walled MWCNTs/Cu VNP was synthesized by hydrothermal method and characterized by FTIR,SEM,EDX and XPS.The composite reached the maximum adsorption of gold ions at p H=4（352 mg/g）.The electrochemical performance of the MWCNTs/Cu VNP electrode was tested and the discharge specific capacity reached 509.8 F/g with a good cycle life of the electrode.In addition,the synthesized composite MWCNTs/Cu VNP has a low charge transfer resistance,which can achieve a fast electron migration rate.Therefore,MWCNTs/Cu VNP is expected to be an excellent electrode material for supercapacitors with broad application prospects.2.Organophosphonic acid modified multi-walled carbon nanotube/dopamine composite（PA-MWCNTs/PDA）was prepared by simple solution reaction method and characterized using FTIR,SEM,EDX and XPS.The maximum adsorption capacity of the composite reached 2089.2 mg/g.The electrochemical performance of the PA-MWCNTs/PDA electrode was tested,and its discharge specific capacity reached 383.6F/g with good cycling stability,and it still had more than 60%capacity after 2500 cycles.In addition,the synthesized composite PA-MWCNTs/PDA exhibited a very low charge transfer resistance,indicating that the material has a fast electron transfer rate.Therefore,PA-MWCNTs/PDA can be used as a supercapacitor electrode material with good application prospects.3.Organophosphonic acid carboxylic acid modified multi-walled carbon nanotube/bismuth sulfide composite（PBTCA-MWCNTs/Bi₂S₃）was prepared by a simple solution reaction method and characterized by FTIR,SEM,EDX,XPS and porous structure analysis（BET）.The composite showed good adsorption of gold ions（2498.25mg/g）and exhibited excellent electrochemical hydrogen storage performance and stability due to the efficient synergistic effect of organophosphonic acid functionalized multi-walled carbon nanotubes with bismuth sulfide.The electrochemical hydrogen storage performance of the PBTCA-MWCNTs/Bi₂S₃ electrode was tested,and its discharge capacity（950.9 m A·h/g）greatly exceeded the relevant values of these two standard materials,and the cycle life of the PBTCA-MWCNTs/Bi₂S₃ electrode was higher than that of Bi₂S₃ and MWCNTs/Bi₂S₃.In addition,the synthesized composite PBTCA-MWCNTs/Bi₂S₃ exhibited very low charge transfer resistance,which implies fast electron transfer.Therefore,PBTCA-MWCNTs/Bi₂S₃ is expected to be an excellent electrochemical hydrogen storage material and can be applied in the field of renewable energy to reduce the use of fossil fuels.