Identification of Highly Active Fe Sites in (Ni,Fe)OOH for Electrocatalytic Water Splitting
Identification of Highly Active Fe Sites in (Ni,Fe)OOH for Electrocatalytic Water Splitting
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DOI：
10.1021/ja511559d
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发表时间：
2015-01-28
影响因子：
15
通讯作者：
Bell, Alexis T.
中科院分区：
文献类型：
--
作者：
Friebel, Daniel;Louie, Mary W.;Bell, Alexis T.
为了开发利用太阳能从水中高效地产生氢的光电化学装置，需要用于析氧反应（OER）的高活性催化剂。在这里，我们确定了一个500倍的OER活性增强的起源，可以实现与混合（Ni，Fe）羟基氧化物（Ni 1-xFexOOH）超过其纯Ni和Fe母体化合物，导致在碱性电解质中的最活跃的目前已知的OER催化剂之一。操作X射线吸收光谱（XAS）使用高能量分辨率荧光检测（HERFD）揭示，Fe 3+在Ni 1-xFexOOH占据八面体网站异常短的Fe-O键距离，诱导与周围的[NiO 6]八面体的边缘共享。使用计算方法，我们建立了这种结构的基序的结果在接近最佳的吸附能OER中间体和低过电位在Fe网站。相比之下，Ni 1-xFexOOH中的Ni位点不是水氧化的活性位点。
Highly active catalysts for the oxygen evolution reaction (OER) are required for the development of photoelectrochemical devices that generate hydrogen efficiently from water using solar energy. Here, we identify the origin of a 500-fold OER activity enhancement that can be achieved with mixed (Ni,Fe)oxyhydroxides (Ni1-xFexOOH) over their pure Ni and Fe parent compounds, resulting in one of the most active currently known OER catalysts in alkaline electrolyte. Operando X-ray absorption spectroscopy (XAS) using high energy resolution fluorescence detection (HERFD) reveals that Fe3+ in Ni1-xFexOOH occupies octahedral sites with unusually short Fe-O bond distances, induced by edge-sharing with surrounding [NiO6] octahedra. Using computational methods, we establish that this structural motif results in near optimal adsorption energies of OER intermediates and low overpotentials at Fe sites. By contrast, Ni sites in Ni1-xFexOOH are not active sites for the oxidation of water.