Spectroelectrochemical study of water oxidation on nickel and iron oxyhydroxide electrocatalysts
Spectroelectrochemical study of water oxidation on nickel and iron oxyhydroxide electrocatalysts
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DOI：
10.1038/s41467-019-13061-0
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发表时间：
2019-11-15
影响因子：
16.6
通讯作者：
Durrant, James R.
中科院分区：
文献类型：
--
作者：
Francas, Laia;Corby, Sacha;Durrant, James R.
Ni/Fe 羟基氧化物是地球上储量最好的水氧化电催化剂。然而，他们卓越表现的起源尚不清楚。在这里，我们采用光谱电化学技术分析了一系列 Ni/Fe 羟基氧化物薄膜上的水氧化动力学：FeOOH、FeOOHNiOOH 和 Ni(Fe)OOH (5% Fe)。测定催化过程中积累的氧化态的浓度和反应速率。 Ni(Fe)OOH 表现出最快的反应动力学，但积累的态较少，从而具有与 FeOOHNiOOH 相似的性能。 FeOOH 中较晚的催化起始归因于氧化态积累的阳极转变。速率定律分析表明，每种催化剂的速率限制步骤涉及四种氧化态的积累，Ni(Fe)OOH 以 Ni 为中心，而 FeOOH 和 FeOOHNiOOH 以 Fe 为中心。最后，我们强调这些积累的物质和反应中间体之间的平衡在确定这些材料的活性方面的重要性。
Ni/Fe oxyhydroxides are the best performing Earth-abundant electrocatalysts for water oxidation. However, the origin of their remarkable performance is not well understood. Herein, we employ spectroelectrochemical techniques to analyse the kinetics of water oxidation on a series of Ni/Fe oxyhydroxide films: FeOOH, FeOOHNiOOH, and Ni(Fe)OOH (5% Fe). The concentrations and reaction rates of the oxidised states accumulated during catalysis are determined. Ni(Fe)OOH is found to exhibit the fastest reaction kinetics but accumulates fewer states, resulting in a similar performance to FeOOHNiOOH. The later catalytic onset in FeOOH is attributed to an anodic shift in the accumulation of oxidised states. Rate law analyses reveal that the rate limiting step for each catalyst involves the accumulation of four oxidised states, Ni-centred for Ni(Fe)OOH but Fe-centred for FeOOH and FeOOHNiOOH. We conclude by highlighting the importance of equilibria between these accumulated species and reactive intermediates in determining the activity of these materials.