The urgent need for a stable, efficient, and affordable oxygen evolution reaction (OER) catalyst has led to the investigation of a vast amount of transition metal materials with multiple different anions. In situ and post catalytic characterization shows that most materials transform during the harsh OER conditions to layered (oxy)hydroxides (LOH). Several open questions concerning these in situ formed LOH remain such as: an explanation for their strongly varying activities, or the effect of the precatalyst structure, leaching anions, and transformation conditions on the formed LOH. Herein, we report on a cobalt selenite precursor, which, depending on pH and potential, transforms irreversibly into two different LOH OER catalysts. Combining multiple electrochemical and analytical methods ex and in situ, we prove that one of these products is near-surface catalytically active and the other one throughout the bulk with an in situ average cobalt oxidation state of 3.2. We deduce a detailed structural model explaining these differences and propose general concepts relating both the precatalyst structure and the transformation conditions to the final catalyst. Further, we apply these models to the most promising non-noble metal catalyst, NiFe LOH.

中文翻译：

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了解从亚硒酸钴前体开始的用于水氧化的本体和表面活性层状（羟基）氢氧化物的形成

迫切需要稳定，高效且负担得起的制氧反应（OER）催化剂，这导致人们对大量具有多种不同阴离子的过渡金属材料进行了研究。原位和后催化表征表明，大多数材料在苛刻的OER条件下会转变为层状（羟基）氢氧化物（LOH）。关于这些原位的几个开放性问题形成的LOH仍然是这样的：对它们强烈变化的活性的解释，或者预催化剂结构，浸出阴离子和转化条件对形成的LOH的影响。在本文中，我们报道了一种亚硒酸钴前体，它根据pH和电势不可逆地转化为两种不同的LOH OER催化剂。组合多个电化学和分析方法的前和在原位，证明这些产品中的一个是近地表的催化活性，而另一个在整个本体与原位平均钴的氧化态为3.2。我们推导了解释这些差异的详细结构模型，并提出了与预催化剂结构和最终催化剂的转化条件相关的一般概念。此外，我们将这些模型应用于最有前途的非贵金属催化剂NiFe LOH。