Impact of Alkali Metal Cations and Iron Impurities on the Evolution of Hydrogen on Cu Electrodes in Alkaline Electrolytes
Impact of Alkali Metal Cations and Iron Impurities on the Evolution of Hydrogen on Cu Electrodes in Alkaline Electrolytes
复制标题
DOI：
10.1149/1945-7111/ab987b
复制
发表时间：
2020-06-11
影响因子：
3.9
通讯作者：
Waegele, Matthias M.
中科院分区：
文献类型：
--
作者：
Li, Xiang;Gunathunge, Charuni M.;Waegele, Matthias M.
电催化铜是开发可将CO和CO2转化为碳氢化合物以及将硝酸盐转化为氨的工艺的关键。析氢反应（HER）经常与这些过程竞争。很少有研究在碱性条件下研究这种反应。在此，我们研究了在碱性条件下在含Na+和Cs+的电解质中在Cu电极上的HER。我们发现，在0.1M的NaOH和CsOH的最高市售纯度等级的溶液中，在电解过程中痕量的铁杂质存款沉积在Cu电极上。结果，HER的速率在相对于可逆氢电极从0.15 V到-0.65 V的11个循环伏安图（CV）的过程中提高了高达约5倍。在去除铁杂质之后，CV作为循环次数的函数是稳定的。通过比较0.1 M NaOH和CsOH溶液的CV值，发现Na+离子向Cs+离子的转化对HER值没有明显影响，并利用密度泛函理论（DFT）对实验结果进行了进一步的解释。我们讨论了我们的研究结果对铜电极上的电催化过程的影响。(C)2020年电化学学会（“ECS”）。由IOP出版有限公司代表ECS出版。
Electrocatalytic Cu is key to the development of processes that can convert CO and CO2 to hydrocarbons, and nitrate to ammonia. The hydrogen evolution reaction (HER) often competes with these processes. Few studies studied this reaction on Cu under alkaline conditions. Herein, we examined the HER on Cu electrodes under alkaline conditions in Na+- and Cs+- containing electrolytes. We found that in 0.1 M solutions of NaOH and CsOH of the highest commercially available purity grades, trace impurities of iron deposit on the Cu electrode during electrolysis. As a result, the rate of the HER is enhanced by up to a factor of approximate to 5 over the course of eleven cyclic voltammograms (CV) from 0.15 to -0.65 V vs the reversible hydrogen electrode. After removal of the iron impurities, the CVs are stable as a function of cycle number. Comparison of the CVs in pre-electrolyzed 0.1 M NaOH and CsOH reveals that changing the cation from Na+ to Cs+ has no measurable effect on the HER. With density functional theory (DFT), we further rationalized our experimental findings. We discuss the implications of our results for electrocatalytic processes on Cu electrodes. (C) 2020 The Electrochemical Society ("ECS"). Published on behalf of ECS by IOP Publishing Limited.