Asymmetrical capacitive deionization (A-CDI) is expected to be a promising desalination technique with high salt removal capacity. In this work, the novel A-CDI are proposed where the negative and positive electrode are Na4Ti9O20 (NTO) and activated carbon (AC), respectively. Basically, the NTO nanotubes with the specifific surface area of 142.43 m2/g have been prepared by hydrothermal reaction. The electrochemical test shows that the specifific capacitance of optimum NTO electrode can reach 120.45 F/g in 1 M Na2SO4 solution with the scan rate of 1 mV/s by employing three-electrodes method. Moreover, the electrosorption capacity of AC/NTO asymmetrical electrodes is approach to 23.35 mg/g in NaCl solution with an initial concentration of 250 ppm. To improve the conductivity of NTO, reduced graphene oxide (rGO) is proposed to couple with NTO, named as rGO@NTO, to constitute the AC/rGO@NTO A-CDI. As a result, the AC/rGO@NTO A-CDI exhibited an ultrahighd esalination capacity of 41.8 mg/g in NaCl solution with an initial concentration of 250 ppm under 1.4 V, whichis almost twice higher than that of AC/NTO electrodes and the highest value among all reported data anywhere.Besides, the charge effiffifficiency of AC/rGO@NTO approaches to 1, implying the co-ions impaction has been
successfully restricted.
