IrO2-SiO2 binary oxide films: Geometric or kinetic interpretation of the improved electrocatalytic activity for the oxygen evolution reaction
IrO2-SiO2 binary oxide films: Geometric or kinetic interpretation of the improved electrocatalytic activity for the oxygen evolution reaction
复制标题
IrO2-SiO2 二元氧化物薄膜：析氧反应电催化活性改进的几何或动力学解释
DOI：
10.1016/j.ijhydene.2011.01.131
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发表时间：
2011-05-01
影响因子：
7.2
通讯作者：
Cao, Chu-Nan
中科院分区：
文献类型：
--
作者：
Zhang, Jia-Jia;Hu, Ji-Ming;Cao, Chu-Nan
我们之前的论文 (Electrochim Acta 2010; 55: 4587-4593) 报道，掺杂二氧化硅（世界上最大的储备氧化物）显着提高了 Ti/IrO2 电极在析氧反应 (OER) 中的表观电化学活性。在本工作中，详细研究了Ti/IrO2 SiO2复合电极的电化学表面结构及其OER反应动力学，以更深入地了解二氧化硅掺入的积极作用。循环伏安法 (CV) 和电化学阻抗谱 (EIS) 测量均表明，混合氧化物电极的“内部”或“外部”活性表面积（通过伏安电荷 (q*) 或双层电容 (C-dl) 量化）在 Ir/Si 摩尔比的研究范围内，随着其中二氧化硅含量的增加而不断增加。二元氧化物薄膜的“孔隙率”（定义为“内部”表面积与“总”表面积之比）表现出比纯 IrO2 薄膜高得多的值。尽管复合电极上OER的表观电催化活性明显高于IrO2电极，但掺入二氧化硅后实际表面积归一化活性有所下降。从归一化极化曲线近似得出的 OER 动力学速率常数也显示出二氧化硅掺杂电极的值显着降低。上述结果表明，二氧化硅掺杂 IrO2 电极的表观电催化活性增强可能仅仅是几何效应的结果。版权所有 (C) 2011，Hydrogen Energy Publications, LLC。由爱思唯尔有限公司出版。保留所有权利。
Our previous paper (Electrochim Acta 2010; 55: 4587-4593) reported that doping silica, the largest reserved oxide in the world, significantly improved the apparent electrochemical activity of Ti/IrO2 electrodes for oxygen evolution reaction (OER). In the present work, the electrochemical surface structure of Ti/IrO2 SiO2 composite electrodes and the reaction kinetics of the OER thereon are investigated in details, to deeper understand the positive role of silica incorporation. Both the cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) measurements indicate either "inner" or "outer" active surface area of the mixed oxide electrodes, which is quantified by the voltammetric charge (q*) or by the double-layer capacitance (C-dl), constantly increases when increasing the silica content therein under the investigated range of Ir/Si molar ratio. The "porosity", defined as the ratio of the "inner" to "total" surface area, of the binary oxide films exhibits much higher values than pure IrO2 film. Although the apparent electrocatalytic activity for the OER at composite electrodes is obviously higher than that at IrO2 electrode, the real surface area-normalized activity declines after silica incorporation. The kinetic rate constants of the OER, approximated from the normalized polarization curves, also show dramatically decreased values at silica-doped electrodes. The above-mentioned results suggest that the enhanced apparent electrocatalytical activity of silica-doped IrO2 electrodes might be merely a result of geometric effect. Copyright (C) 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.