Journal of Applied Electrochemistry ( IF 2.384 ) Pub Date : 2021-07-25 , DOI: 10.1007/s10800-021-01601-w Rylan Clark 1 , Abigail Moore 1 , Marissa MacInnis 1 , Erwan Bertin 1
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The electrooxidation of urea was investigated on Ni90Fe10 electrodeposited films as an alternative reaction to the oxygen evolution reaction (OER) during CO2 electrolysis. The results show an excellent activity, 135 mA cm−2geo (by cyclic voltammetry) and stability (90–76.5 mA cm−2geo) over 30 min in alkaline media (NaOH 1 M + 0.25 M urea). The activity was extremely pH dependent, decreasing sharply at pH 12–13, but remaining higher than the OER at all pH investigated. The activity could be recovered by replacing the electrolyte by a fresh solution. The absence of correlation between the amount of NiOOH sites formed and the current measured at different pH suggests a limitation, either kinetic in the formation of NiOOH or in the amount of hydroxyl anions available, at pH < 14. Nevertheless, at pH ≈ 14, chronopotentiometry measurements revealed a gain of 120 mV in the potential needed to achieve a current density of 50 mA cm−2geo. Meanwhile, the production of formate at a tin cathode remained constant or slightly increased in the presence of urea at the anode at all potentials tested.
Graphic abstract
中文翻译：
CO2电解过程中尿素氧化作为潜在阳极反应的研究
在 Ni 90 Fe 10电沉积薄膜上研究尿素的电氧化反应作为 CO 2电解过程中析氧反应 (OER) 的替代反应。结果显示出优异的活性、135 mA cm -2 geo（通过循环伏安法）和稳定性（90–76.5 mA cm -2 geo) 在碱性介质 (NaOH 1 M + 0.25 M 尿素) 中超过 30 分钟。活性高度依赖于 pH，在 pH 12-13 时急剧下降，但在所有研究的 pH 下仍高于 OER。可以通过用新鲜溶液替换电解质来恢复活性。形成的 NiOOH 位点的数量与在不同 pH 下测量的电流之间缺乏相关性表明，在 pH < 14 时，NiOOH 形成的动力学或可用的羟基阴离子数量存在限制。然而，在 pH ≈ 14 时，计时电位测量显示实现 50 mA cm -2 geo电流密度所需的电位增益为 120 mV. 同时，在所有测试电位下，在阳极存在尿素的情况下，锡阴极的甲酸盐产量保持不变或略有增加。
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