Purification of residual Ni and Co hydroxides from Fe‐free alkaline electrolyte for electrocatalysis studies
Purification of residual Ni and Co hydroxides from Fe‐free alkaline electrolyte for electrocatalysis studies
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纯化无铁碱性电解液中残留的镍和钴氢氧化物，用于电催化研究
DOI：
10.1002/celc.202200279
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发表时间：
2022
期刊：
影响因子：
4
通讯作者：
Boettcher, Shannon
中科院分区：
文献类型：
--
作者：
Liu, Lu;Twight, Liam P;Fehrs, Jessica L;Ou, Yingqing;Sun, Deen;Boettcher, Shannon
在析氧反应电催化实验中控制Fe杂质浓度是至关重要的，这样可以明确地分配活性和机理细节。制备不含Fe的KOH电解质的既定方法是通过使用颗粒状Ni（OH）2或Co（OH）2作为吸收剂来从KOH或其他中性至碱性电解质中去除Fe。然而，该方法在电解质中产生残留的Ni或Co物质，其可以再沉积在工作电极上。因此，目前的除铁方法可能会影响OER的研究。在这项工作中，我们比较了两种不同的方法：连续电解和纳米过滤，以从无铁碱性电解质中去除Ni和/或Co物质。我们发现最佳方法是使不含Fe的电解质通过亲水性0.1 μm聚醚砜过滤器，该过滤器将1 M KOH中的Ni物质浓度降低至单个ppb水平。 该结果表明，剩余的Ni或Co物质本质上主要是颗粒，与它们作为离子的小溶解度一致。相比之下，电解质的延长预电解仅去除了一部分Ni/Co。
It is critical to control Fe impurity concentrations in oxygen‐evolution‐reaction electrocatalysis experiments so that unambiguous assignments of activity and mechanistic details can be made. An established method to prepare Fe‐free KOH electrolyte is by using particulate Ni(OH)2or Co(OH)2as absorbents to remove the Fe from KOH or other neutral‐to‐alkaline electrolytes. However, this method yields residual Ni or Co species in the electrolyte which can be redeposited on the working electrode. Thus, current methods of Fe removal could convolute studies of OER. In this work, we compared two different methods, continuous electrolysis and nano‐filtration, to remove the Ni and/or Co species from Fe‐free alkaline electrolyte. We found the best approach is to pass the Fe‐free electrolyte through a hydrophilic 0.1 μm polyethersulfone filter which decreases the Ni species concentration in 1 M KOH to single ppb levels. This result suggests the remaining Ni or Co species are primarily particulate in nature, consistent with their small solubility as ions. In comparison, extended pre‐electrolysis of the electrolyte removed only a portion of the Ni/Co.