Ti/Sb-SnO_2电极电解后的表面状态变化

Surface Analysis of Ti/Sb-SnO_2 Electrode after Electrolysis

针对电极表面发生电化学反应而影响电极稳定性的问题,研究了0.1mol·L-1的Na2SO4溶液中以5×10-3 A·cm-2恒电流电解300h后Ti/Sb-SnO2电极表面状态的变化,同时采用扫描电镜、元素分析和X射线衍射检测了该表面的状态,用电感耦合等离子体发射光谱仪检测了电解后溶液中的金属含量。结果表明:经长时间电解后的Ti/Sb-SnO2电极表面出现了氧化物层局部溶解及脱落的情况;电解完成后的溶液中检测到Sn元素;电极表层的物质仍为Sb-SnO2,但衍射峰强度有所降低,Ti峰强度大幅度升高。由此推测,表层氧化物层的溶解、局部区域的脱落以及基底与表面层之间的钝化可能是造成Ti/Sb-SnO2电极在长时间使用后失稳的主要原因。该结果可为改善Ti/Sb-SnO2电极表面形貌、提高表层氧化物负载量和电极稳定性研究提供参考。

The change in the surface morphology in electrochemical processes can directly affect the stability of the electrode. Ti/Sb-SnO2, the target electrode, was electrolyzed in the Na2SO4 solution （0.1 mol · L-1） under constant current density condition （SX 10-3 A · cm^-2） for 300 h. scanning electron microscope, energy dispersive spectrometer and X-ray diffraction （XRD） were used to determine the change in the surface morphology. Inductively coupled plasma optical emission spectrometry was used to determine the metal content in the electrolyte. Then the possible reason for the deactivation of the Ti/Sb-SnO2 electrode after long time running was proposed. The SEM results show that the surface layer of the Ti/Sb-SnO2 electrode was partially dissolved and some parts were even detached from the titanium base after electrolysis. The Sn element was detected in the electrolyte after electrolysis, suggesting that Sb-SnO2 was indeed dissolved in the electrolyte. The XRD analysis indicates that the surface layer was still Sb-SnO2 but the diffraction peak intensity decreased. It appears that the anode deactivation may result from the dissolution and detachment of the oxide layer and the passivation of substrate. The result can be useful for the enhancement of the electrode stability.