Preparation Of Graphene-based Composites And Their Application In Water Treatment And Supercapacitors

Graphene is a unique two-dimensional structural carbon-based material.Because of its high specific surface area,excellent electrical conductivity,and atomic-level thickness,it improves application prospects in the fields of water treatment and supercapacitors.However,the poor mechanical properties and low adsorption capacity of graphene-based aerogels prepared by hydrothermal self-assembly limit its application.Therefore,it is important to enhance its mechanical properties and adsorption capacity.The use of graphene as an electrode material for a supercapacitor has a smaller specific capacitance and limits its application.Therefore,the introduction of theoretically higher capacitance than the transition metal hydroxide and graphene composites effectively improves the electrochemical performance.The research content of this article is developed by the following three aspects:A graphene-based composite aerogel with amphiphilic character was prepared by hydrothermal reduction-crosslinking and self-assembly method.PVA was used as a crosslinking agent and ethylenediamine was used as a reducing agent.The reaction temperature,reaction time,GO concentration,cross-linking were investigated.The amount of the agent and the amount of ethylenediamine used affect the aerogel adsorption and mechanical properties.Composite aerogels have excellent properties such as high porosity,excellent adsorption capacity,and good mechanical properties.Graphene-Co Ni-LDHs composites were prepared by electrostatic interaction between graphene and metal hydroxides.The synergy between the two-dimensional structure of graphene in the electrode material and the Co Ni-LDHs of the two-dimensional nanosheet structure provides more active sites,so that the composite has excellent electrochemical properties.At a current density of 1 A/g,the specific capacitance is as high as 1360 F/g.After 2000 charge and discharge cycles at a current density of 4 A/g,the capacitance retention rate is 76.7%.The electrochemical performance of Co Ni-LDHs is superior to that of Co Ni-LDHs.One-step hydrothermal method for the preparation of petal-like cobalt nickel hydroxide Co_xNi_1-x（OH）₂ and graphene-based cobalt nickel hydroxide composite aerogels,petal-like cobalt nickel hydroxide and three-dimensional network structure of graphene-based cobalt nickel hydroxide composite aerogels all have superior electrochemical properties.When the current density is 1 A/g,the specific capacitance of Co_xNi_1-x（OH）₂ is as high as 1592 F/g.After being cycled and charged 2000 times at a current density of 4 A/g,the capacitance retention rate is 79.9%.