Preparation Of Rare Earth-Doped Ti/TiO₂Film Electrode And The Study Of Electrochemical Performance

Ti/nano-TiO2film electrodes were prepared using sol-gel method. The electrochemical properties, surface morphologys and crystallinities of the Ti/nano-TiO2films were characterized by cyclic voltammetry (CV)、scanning electron microscopy (SEM) and x-ray diffraction (XRD). These results showed that the optimum preparation conditions of Ti/nano-TiO2film electrodes:pH=2-3,1.2mL of deionized water and0.88mL of acetylacetone for the nano-TiO2sol; An appropriate amount of sodium dodecyl benzene sulfonate (dispersing agent); A calcination temperature of450℃and7layer coatings on electrode surface.A Ce-doped or La-doped nano-TiO2film electrode was synthesized by the sol-gel method. The structures, morphologys and electrocatalytic activities of as-prepared TiO2film electrodes were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The XRD and SEM results indicated that the doping made lattice distortion of TiO2nanoparticles and the TiO2particle size became smaller after Ce or La doping. XPS analyses indicated that the Ce or La doping ion was existed in the form of Ce4+or La3+and the doped TiO2combined to form the Ce-O-Ti or La-O-Ti bond during the coating process. The electrocatalytic activity of Ce or La doped nano-TiO2film electrodes with different Ce/Ti or La/Ti molar ratios showed that the electrode with Ce/Ti molar ratio of0.003gave the highest cathodic peak current, the peak curren was4times higher than that of the undoped. Similarly, the La/Ti molar ratio of0.005gave the highest cathodic peak current which was3times higher than that of the undoped. EIS showed that the value of Ret of the Ti/Ce nano-TiO2film electrode or Ti/La nano-TiO2film was much smaller than the value of the Ti/nano-TiO2film electrode.Electrocatalytic properties were evaluated by the electroreduction of maleic acid (MA) on the Ce or La doped nano-TiO2film electrodes in sulfuric acid solutions. The results demonstrated that the optimum molar ratio of Ce/Ti was0.003:1and the optimum molar ratio of La/Ti was0.005:1. The Ti/Ce nano-TiO2(Ce/Ti=0.003) electrode showed a higher electrocatalytic activity (4.5times higher) than the undoped and the peak current of Ti/La nano-TiO2(Ce/Ti=0.005) electrode was3.5times higher than the undoped, which resulted in a high yield of succinic acid (SA)(98%) and a high current efficiency (91%) in the potenstiostatic preparative reduction on Ti/Ce nano-TiO2(Ce/Ti=0.003) electrode and a yield of succinic acid (SA)(91%), a current efficiency (87%) on Ti/nano-TiO2(La/Ti=0.005) electrode. These results demonstrated that the Ce or La doped nano-TiO2film electrodes are interesting and useful electrode materials for reducing MA.According to the electrolysis experiment results, the surface of the Ti/Ce nano-TiO2or Ti/La nano-TiO2film electrode is no different before and after the electrolysis. This demonstrated that the Ce or La nano-TiO2film electrode are very stable.