Preparation Of Nano Titanium Nitride Film And Its Application In All Vanadium Redox Flow Battery

In this paper,nanometer titanium nitride films with two kinds of nanowires and nanotubes were successfully prepared by using hydrothermal and anodic oxidation method.The surface morphology,composition and structure of TiN nanowires and nanotubes were characterized.The prepared electrodes are proposed as a novel catalyst towards V???/V???redox couple for the negative electrode in all vanadium redox battery,and the charge and discharge performance of the cathode material was evaluated.Firstly,titanium nitride nanowires?TiN NWs?were directly prepared on a titanium foil by a hydrothermal method followed by nitridation in ammonia atmosphere.The composition,microstructure,and electrochemical properties of the TiN NWs were characterized using scanning electron microscopy,high-resolution transmission electron microscopy,X-ray diffraction,X-ray photoelectron spectroscop y,cyclic voltammetry,and electrochemical impedance spectroscopy.The results show that the nanowires have diameters of 20⁵0 nm and are 5 ?m long.The surfaces of the TiN NWs comprise Ti-N,Ti-O,and O-Ti-N chemical states.The electrochemical activity and reversibility for the electrode processes of V???/V???couple on the TiN NWs are significantly improved due to the introduced Ti-N,Ti-O,and O-Ti-N chemical states.The transfer resistance for the cathodic reduction of V???on the TiN NWs is about 20 times and 10 times smaller than on TiO2 NWs and graphite electrodes,respectively.The rate constant of charge transfer on the TiN NWs electrode was determined to be 5.21×10-4 cm·s^-1,which is about 5 times larger than the rate constant on graphite electrodes(9.63×10-5 cm·s^-1).It can be attributed to the one-dimensional nanowire microstructure and its higher electrocatalytic activity.Then,titanium dioxide nanotubes?TiO2 NTs?were grown in situ on the surface of titanium fo il by anodic oxidation,and converted into titanium nitride nanotubes?TiN NTs?by ammonia reduction.The results confirm that the microstructure of nanotubes remains at high temperature after nitriding.The diffusion coefficient of V???is 1.05×10^-3 cm²·s^-1,which is about 10 times than that of graphite electrode.The TiN NTs electrode exhibits excellent electrocatalytic activity and reversibility fo r V???/V???,which could be ascribed to the large electrochemical real surface area and fast transfer channel.When the charge and discharge current density is 10 mA·cm-2,TiN nano film as the negative electrode of vanadium battery,the energy efficienc y can reach up to 73.60%,which has potential application prospect.