Conversion of electrodeposited Co(OH)2 to CoOOH and Co3O4, and comparison of their catalytic activity for the oxygen evolution reaction
Conversion of electrodeposited Co(OH)2 to CoOOH and Co3O4, and comparison of their catalytic activity for the oxygen evolution reaction
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DOI：
10.1016/j.electacta.2014.04.036
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发表时间：
2014-09-10
影响因子：
6.6
通讯作者：
Switzer, Jay A.
中科院分区：
文献类型：
--
作者：
Liu, Ying-Chau;Koza, Jakub A.;Switzer, Jay A.
氢氧化钴，β-Co(OH)(2)，是从三(乙二胺)钴(III)的碱性溶液中进行阴极电沉积。 Co(OH)(2)晶体生长成微锥形貌，并且在阳极电位下表面变成CoOOH。 Co(OH)(2) 薄膜在 95 摄氏度的 1 M KOH 中通过电化学氧化完全转化为 CoOOH，并在 300 摄氏度的空气中通过热分解完全转化为 Co3O4。 Co(OH)(2)和CoOOH薄膜在Au(111)上以[001]取向生长，转化后的Co3O4薄膜具有[111]取向。转化后保留了整体形态。然而，在 CoOOH 和 Co3O4 微锥的表面上观察到粗糙度增加。薄膜的电化学活性面积是通过乙腈与六氟磷酸四丁基铵电解质中的双层电容测量来估计的。 CoOOH的粗糙度系数为9.4，Co3O4的粗糙度系数为63.6。在室温下，通过 Tafel 分析比较薄膜在 O-2 饱和 1 M KOH 中的析氧反应 (OER) 催化活性。当在 Tafel 分析中使用几何面积时，CoOOH 和 Co3O4 薄膜似乎表现出不同的 Tafel 行为，其中 Co3O4 是优异的催化剂。然而，当针对测量的电化学活性面积校正观察到的电流密度时，两个塔菲尔图的线性区域落在同一条线上。结果表明，两种材料上 OER 的活性物质（可能是 Co(IV)）是相同的。 CoOOH和Co3O4的塔菲尔斜率均为60 mV dec(-1)，交换电流密度为6.1 x 10(-11) A cm(-2)。论文中概述的转化方法提供了一种生产具有大电化学活性面积的 Co3O4 的方法。 (C) 2014 Elsevier Ltd. 保留所有权利。
Cobalt hydroxide, beta-Co(OH)(2), was electrodeposited cathodically from an alkaline solution of tris(ethylenediamine)cobalt(III). The Co(OH)(2) crystals grew into a microcone morphology and the surface became CoOOH at anodic potentials. The Co(OH)(2) film was fully converted to CoOOH by electrochemical oxidation at 95 degrees C in 1 M KOH and to Co3O4 by thermal decomposition at 300 degrees C in air. The Co(OH)(2) and CoOOH films grew with a [001] orientation on Au(111), and the converted Co3O4 films had a [111] orientation. The overall morphology was retained upon conversion. However, an increase in roughness was observed on the surface of the CoOOH and Co3O4 microcones. The electrochemically active area of the films was estimated from double layer capacitance measurements in acetonitrile with tetrabutylammonium hexafluorophosphate electrolyte. The CoOOH had a roughness factor of 9.4, and the Co3O4 had a roughness factor of 63.6. The catalytic activities of the films for the oxygen evolution reaction (OER) were compared by Tafel analysis in an O-2 saturated 1 M KOH at room temperature. The CoOOH and Co3O4 films appeared to exhibit different Tafel behavior with Co3O4 being the superior catalyst when the geometric area was used in the Tafel analysis. However, when the observed current densities were corrected for the measured electrochemically active areas, the linear regions of the two Tafel plots fell on the same line. The results suggest that the active species, likely Co(IV), for the OER is the same on both materials. Both CoOOH and Co3O4 had a Tafel slope of 60 mV dec(-1) and an exchange current density of 6.1 x 10(-11) A cm(-2). The conversion method outlined in the paper provides a means to produce Co3O4 with a large electrochemically-active area. (C) 2014 Elsevier Ltd. All rights reserved.