| Titanium dioxide nanotubes(TiO2 NTs)have some characteristics including large specific surface area,tubular structure and controllable size and so on.However,titanium dioxide is a semiconductor and the electrochemical performance is poor.In recent years,the modifications of TiO2 NTs through coating metal oxides or doping have attracted wide attentions from researchers.In this paper,firstly,the characteristics and applications of the TiO2 NTs/Ti electrode and modified TiO2 NTs/Ti electrode were introduced.The TiO2 NTs/Ti electrode was prepared by anodic oxidation.The obtained TiO2 NTs/Ti electrode was modified by coating RuO2 on the electrode surface through thermal decomposition,or the TiO2 NTs/Ti electrode was electro-reduced and then the RuO2 was coated by thermal decomposition.The electrochemical performances of the modified TiO2 NTs/Ti electrodes were studied.The main works are as follows:1.The TiO2 NTs/Ti electrode was prepared in different electrolytes by anodic oxidation.By analyzing the current density-time curve during the anodizing process,we preliminarily discussed the formation mechanism of TiO2 NTs.The microstructure,the species and content of elements in the micro-region,and the phase structure of the titanium electrode after anodizing were characterized by atomic force microscope(AFM),scanning electron microscopy(SEM),energy dispersive spectroscopy(EDS),and laser micro Raman spectrometer.The electrochemical performance of TiO2 NTs/Ti electrode was studied by cyclic voltammetry(CV).The experimental results show that porous film with an aperture of about 1-2 ?m was formed on the surface of the titanium substrate by anodic oxidation in the 0.1 mol L-1 NH4F + 1 mol L-1 H2SO4 electrolyte.The uniform nanotubes on the titanium substrate can be obtained by anodic oxidation in the 1 wt.%NH4F + 2 vol.%H2O +ethylene glycol electrolyte.The nanotube has a diameter of 65-75 nm,a tube length of 1-1.7 ?m,and the upper end of the nanotube was opened and the bottom was closed.The electrolyte attached on the surface of the TiO2 NTs/Ti electrode can be removed by annealing at 450 ?.By this process,the TiO2 NTs was also transformed from amorphous to anatase structure,and the resulting electrode has a certain degree of enhanced electrical conductivity.2.The RuO2/Ti and RuO2/TiO2 NTs/Ti electrodes were prepared by thermal decomposition.The microstructure,species and content of elements in the micro-region and phase structure of RuO2/Ti and RuO2/TiO2 NTs/Ti electrodes were studied by SEM,EDS and X-ray diffraction(XRD).The electrochemical performances of the resulting electrodes for oxygen/chlorine evolution reactions were studied by CV,LSV,Tafel curve and chronopotentiometry.The life time of the resulting electrodes was evaluated by the accelerated life method.The experimental results show that the real surface area of the RuO2/TiO2 NTs/Ti electrode and the binding force of the RuO2 to the Ti substrate can be increased by adding the middle layer of titanium dioxide nanotube between the titanium substrate and the RuO2 coating,compared with the RuO2/Ti electrode,the RuO2/TiO2 NTs/Ti electrode has more active sites,so that it has a lower potential for oxygen/chlorine evolution reactions and longer accelerated life.3.The RuO2/TiHxOy/Ti electrode was obtained by electro reduction,followed by coating RuO2 through thermal decomposition on the TiO2 NTs/Ti electrode.The formation of TiHxOy was preliminarily discussed through the analysis of i-t curve in the process of electro reduction.The electrochemical performances of the modified electrode for oxygen/chlorine evolution reactions were preliminarily studied by CV,LSV and chronopotentiometry.The accelerated life of the electrode was evaluated by accelerated life test.The experimental results show that the potential of chloride evolution reaction at the RuO2/TiHxOy/Ti electrode and the accelerated life are similar with those at the RuO2/TiO2 NTs/Ti electrode,but the oxygen evolution potential at the RuO2/TiHxOy/Ti electrode was increased. |
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