Self-supporting macroscopic carbon nanotubes microfiber hybrid electrodes for capacitive deionization

A promising self-supporting macroscopic carbon nanotubes(CNTs) electrode was prepared by catalytic chemical vapor deposition method through CNTs growth on a three-dimensional network of sinter-locked conductive 8 μm-nickel fibers, namely CNTs/SMF-Ni(CNTs mass fraction 50%), in which the Ni-microfibrous network serves as current collector and CNTs as ion storage reservoir. This approach permits the desirable large area fabrication and unique combinations of binderlessness, excellent thermal/electrical conductivity, macro-/meso-sized hierarchical porous structure, and individual/uniform dispersion of CNTs. This CNTs electrode was characterized by scanning electron microscopy(SEM), transmission electron microscopy(TEM), Fourier transform infared spectrometry(FTIR), N ₂ isothermal adsorption-desorption and X-ray diffraction. The desalination performance for 0.01%NaCl aqueous solution was tested using the CNTs/SMF-Ni as the electrodes of the capacitive deionization. Owing to the excellent ion diffusivity, high conductivity and high mesopore surface area, such hybrid electrodes delivered the maximum electrosorption capacity of 159 μmol/g CNTs with a salt removal rate of 57%, using the direct current voltage of 1.2 V and water flow rate of 5 mL/min. The desalination performance of such hybrid electrodes could be further promoted by oxidation treatment using H ₂O ₂ solution, due to significantly enhanced hydrophilicity stemmed from formation of large amount of O-containing groups on the CNTs surface.