High capacitance and long cycle-life of nitrogen doped reduced graphene oxide

Nitrogen-doped graphene–TiOxNy nanocomposite electrode for highly efficient capacitive deionization

“…Compared to the pristine rGO, rGO-TiO 2 , and AC, the NG-TiO x N y material exhibited signicantly lower salt retention rate, which is less than 50% at 25 min. The higher performance of NG-TiO x N y can be attributed to the enhanced ion absorbing capacity due to the nitrogen doping process with higher binding capacity between nitrogen doping sites and the ions, 33,46 which is also corresponded with the better electrochemical performance. Furthermore, the higher CDI performance of the electrodes aer nitrogen doping can be explained enhanced ions storage capacity in the surface vacancies formed during the ammonia heat treatment.…”

“…The increase of the BET surface area is attributed to the loaded TiO x N y nanoparticles with small crystal size and could be further explained by the surface vacancies generated during the ammonia heat treatment, which may result in a positive effect on ion absorbing. 45,46 The SEM images in Fig. S4 † at 1 mm magnitude indicates the layered structure of the graphene nanosheet.…”

“…3b), demonstrating the nitrogen-enriched doped surface, which furthers the surface absorbing capacity. 46,47 To further study the chemical composition of the NG-TiO x N y electrode material. X-ray photoelectron spectroscopy (XPS) was utilized, as shown in Fig.…”

“…59 The mass ratio of N-doped graphene : TiO x N y is approximately 2 : 1, which results in a signicant decrease of specic area and electrochemical active area as opposed to sole N-doped graphene and a further decrease of specic capacitance. 46,60,61 Fig. 5c shows the I-V curves for electrolyte solutions with concentrations of 0.1 mol L À1 , 0.5 mol L À1 , and 1 mol L À1 .…”

“…The higher capacitance can be attributed to the nitrogen-doped sites on the graphene layer and the surface vacancies generated during the Ti species nitridation. 46,63 Electrochemical Impedance Spectroscopy (EIS) analysis, which is usually used for evaluating the electrical conductivity of electrode materials, was performed to further investigate the electrochemical properties of the synthesized NG-TiO x N y . The Nyquist plots for the electrode material are shown in Fig.…”