涂层IrO2+Ta2O5钛阳极在析氧过程中的形貌和成分变化

作者用热分解法制备钛基IrO2+Ta2O5涂层阳极,涂层制备态在373 K马弗炉中长时间时效处理,然后在0.5mol/L H2SO4介质中、4A·cm-2电流密度下进行强化寿命试验.用自带能谱仪(EDS)的场发射高分辩电子扫描显微镜(SE-SEM)和X射线衍射仪(XRD)进行电解前后的表面形貌和成分分析.研究结果显示涂层制备态在373K马弗炉中长时间时效处理时,金红石IrO2织构优先生长且晶面间距随时效时间延长而增加;电解过程中涂层的失效过程为气体氧对涂层界面的冲刷造成涂层逐层腐蚀消耗,接着涂层产生裂纹和扩展,导致涂层剥落;化学成分方面,涂层氧化铱优先消耗和氧化钛逐步积累.

Variation of Morphology & Composition of IrO2+Ta2O5 Coated Titanium Anode in OER

A coating layer of IrO2+Ta2O5 as a catalytical active layer on a titanium substrate was prepared by thermal decomposition method and age treatment in air at 373K.After intensifying life time test in aqueous solution of H2SO4 0.5mol/L at 4A.cm-2 current density,the morphology and composition were investigated by field emission scanning electron microscopy(FE-SEM) with energy dispersive X-ray spectrometry(EDS) and X-ray diffraction(XRD) and X-ray photoelectron spectroscopy(XPS).The XRD and XPS results revealed that the texture of IrO2 rutile crystal is preferentially grown and its crystal plane spacing increases with aging time.The results also showed that the oxygen evolution leads up to the corrosion of the coating layer by layer,and consequently cracks are initiated and extended,resulting in fragmentation and peeling,and that the selective consumption of iridium oxide and the presence of titanium element in outermost coating layer,this might be originated from Ti substrate which is dissolved and diffused through the coating layer defects during electrolysis process.