La掺杂对Ti/Sb-SnO2电极改性机制的研究：电化学分析

The study of Lanthanum doping on the modification mechanism of Ti/Sb-SnO2 electrode : electrochemical analysis

摘要:

为研究稀土掺杂对SnO₂催化电极的改性机理。本文采用溶胶凝胶法制备了La掺杂Ti/Sb-SnO₂电极,以苯酚为目标有机物,考察了电极的电化学性能。极化曲线和Mott-Schottky分析表明: La改性Ti/Sb-SnO₂电极的析氧电位先增大后减小,且在2.0V电位下Sn:Sb:La 100:10:1.5电极交换电流密度值最大；改性后电极的平带电势负移,Mott-Schottky拟合直线斜率从2.96降为1.66,活性表面积增大,载流子浓度提升。循环伏安和交流阻抗分析表明: 掺杂后电极电化学反应电阻减小,活性电荷由14.1μF提升至322μF；苯酚直接氧化峰电流增大,峰电位减小。以上结果解释了电极电催化活性提升的内在原因。

Abstract:

In order to study the modification mechanism of Lanthanum doping on SnO₂ catalytic electrodethe. In this paper, La doped Ti/Sb-SnO₂ electrode was prepared by sol-gel method. Taking phenol as a target organics, the electrochemical performance of the electrode was investigated. Polarization curves and Mott-Schottky curve of the prepared electrodes were tested, the analysis results showed that the oxygen evolution potential of lanthanum modified Ti/Sb-SnO₂ electrode is first increased and then decreased. And the exchange current density of Sn:Sb:La 100:10:1.5 electrode is maximum under 2.0V potential. The La doping promotes the negative shift of flat band potential and the slope of fitting straight-line of Mott-Schottky curve has fallen from 2.96 to 1.66, enhances the active surface area, improve carrier concentration correspondingly. Cyclic voltammetry and electrochemical impedance spectroscopy of prepared electrodes were performed, the results showed that the electrochemical reaction resistance of the doped electrode is decreased, the active charge can be increased from 14.1μF to 322μF. At the same time, the peak current of the direct oxidation of phenol is enhanced, the peak potential is decreased. The above results explain the intrinsic reason for the improvement of the electrocatalytic activity.