氮化钛纳米线的结构特征及其对V(Ⅱ)/V(Ⅲ)的电极过程

摘要

采用水热法在钛片表面直接生长二氧化钛纳米线(TiO2 NWs),随后通过氨氮还原转化为氮化钛纳米线(TiN NWs).利用扫描电镜(SEM)、透射电镜(TEM)、X射线光电子能谱(XPS)、循环伏安法(CV)和电化学阻抗谱(EIS)对材料的组成、微观结构和电极过程动力学的特征进行表征.结果表明,TiN NWs纳米线的直径约20-50 nm,长度超过5 μm,其表面可能存在Ti-N键、Ti-O键和O-Ti-N键,这种含氮和含氧的化学态使得TiN NWs电极具有更好的电导性和电催化性能.TiN NWs电极对V(Ⅱ)/V(Ⅲ)离子表现出更好的可逆性,其电极反应电阻Rct值比TiO2 NWs和石墨电极分别小约20倍和10倍.同时,TiN NWs电极上V(Ⅲ)还原反应的速率常数为5.21 x10-4 cm.s-1,约是石墨电极(速率常数9.63 ×10-5 cm·s-1)的5倍,这可归因于TiN NWs的一维纳米线微结构特征及其较高的电催化性能.%Titanium nitride nanowires (TiN NWs) were directly prepared on a Ti 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 (SEM),high-resolution transmission electron microscopy (HR-TEM),X-ray diffraction (XRD),X-ray photoelectron spectroscopy (XPS),cyclic voltammetry(CV),and electrochemical impedance spectroscopy (EIS).The results show that the nanowires have diameters of 20-50 nm and are 5 μm 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(Ⅱ)N(Ⅲ) 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(Ⅲ) 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 x10-4 cm.s-1,which is about 5 times larger than the rate constant on graphite electrodes (9.63x10-5 cm.s-1).