Significantly enhanced capacitance deionization performance by coupling activated carbon with triethyltetramine-functionalized graphene

Capacitance deionization technology differs from traditional demineralization technology; its desalination effect depends mainly on the electrode material. The material surface area, pore size, conductivity, and hydrophilicity affect the capacitance deionization performance. Here, various ethyleneamine-functionalized graphene oxide nanocomposites were synthesized by a simple one-pot organic reaction. The nitrogen atom of the ethyleneamine can improve the adsorption performance owing to the interfacial interaction between lone pair electrons and salt ions, and NH2 groups can react with the oxygen-containing group of graphene oxide to generate a stable porous nanostructure. The capacitance deionization device that is based on triethyltetramine-modified graphene oxide (TETA-mGO) exhibits an excellent specific capacitance (104.13 F/g) and salt electrosorption capacity (9.50 mg/g) at 1.6 V. To enhance the deionization performance and reduce the cost, activated carbon was introduced to couple with TETA-mGO to construct a composite electrode (AC/TETA-mGO) with a reasonable ratio of TETA-mGO and activated carbon. Among them, the novel AC/TETA-mGO-10% composite exhibits a superior electrochemical performance with an improved specific capacitance of 147.29F/g. In addition, AC/ TETA-mGO-10% also exhibited excellent salt adsorption capacity (15.17 mg/g) in a low concentration of NaCl solution. These results demonstrate that ethyleneamine-functionalized graphene oxide can improve the electroadsorption performance, and similarly the coupling of activated carbon and TETA-mGO shows potential as an advanced, inexpensive electrode material for capacitive-deionization application.