A layered β-NiOOH crystal with undercoordinated facets is an active and economically viable nonnoble catalyst for the oxygen evolution reaction (OER) in alkaline electrolytes. However, it is extremely difficult to enclose the β-NiOOH crystal with undercoordinated facets because of its inevitable crystal transformation to γ-NiOOH, resulting in the exfoliation of the catalytic surfaces. Herein, we demonstrate {111}-faceted Ni octahedra as the parent substrates whose surfaces are easily transformed to catalytically active β-NiOOH during the alkaline OER. Electron microscopic measurements demonstrate that the horizontally stacked β-NiOOH on the surfaces of Ni octahedra has resistance to further oxidation to γ-NiOOH. By contrast, significant crystal transformation and thus the exfoliation of the γ-NiOOH sheets can be observed on the surfaces of Ni cubes and rhombic dodecahedra (RDs). Electrocatalytic measurements show that the β-NiOOH formed on Ni octahedra exhibits highly enhanced OER durability compared to the Ni cubes, Ni RDs, and the state-of-the-art Ir/C catalysts.

中文翻译：

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NiOOH无剥落镍八面体作为碱性电解质中高活性和持久性氧分解反应的电催化剂

具有不协调的小平面的层状β-NiOOH晶体是一种活性且经济上可行的非贵金属催化剂，可用于碱性电解质中的氧释放反应（OER）。但是，由于β-NiOOH晶体不可避免地转变成γ-NiOOH，因此很难将β-NiOOH晶体围成小平面，从而导致催化表面的剥离。在此，我们证明{111}面Ni八面体为母体，其表面在碱性OER过程中容易转变为催化活性的β-NiOOH。电子显微镜测量表明，八面体镍表面上水平堆积的β-NiOOH具有抗进一步氧化成γ-NiOOH的能力。相比之下，可以在Ni立方和菱形十二面体（RDs）的表面上观察到明显的晶体转变，从而观察到γ-NiOOH片的剥落。电催化测量表明，与八角形镍，Ni RD和最先进的Ir / C催化剂相比，在八面体Ni上形成的β-NiOOH表现出更高的OER耐久性。