Operando Spectroscopic Identification of Active Sites in NiFe Prussian Blue Analogues as Electrocatalysts: Activation of Oxygen Atoms for Oxygen Evolution Reaction
Operando Spectroscopic Identification of Active Sites in NiFe Prussian Blue Analogues as Electrocatalysts: Activation of Oxygen Atoms for Oxygen Evolution Reaction
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作为电催化剂的 NiFe 普鲁士蓝类似物活性位点的操作光谱鉴定：氧原子的活化以进行析氧反应
DOI：
10.1021/jacs.8b05294
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发表时间：
2018-09-12
影响因子：
15
通讯作者：
Zhang, Shuo
中科院分区：
文献类型：
--
作者：
Su, Xiaozhi;Wang, Yu;Zhang, Shuo
开发高效的析氧反应（OER）催化剂并了解其活性是电化学转化技术的关键。在这里，我们报告NiFe普鲁士蓝类似物（PBA）作为一个有前途的电催化剂在碱性条件下的OER。该材料具有令人印象深刻的258 mV的低过电位，达到10 mA cm（-2）的电流密度。经电化学处理后，催化剂完全转变为无定形氢氧化镍，Ni（OH）（2）为活性物种。Operando X射线光谱研究进一步发现，这种原位生成的Ni（OH）（2）显示出独特的特征，其允许在施加的电势下去质子化，从而产生含有Ni 4+离子的NiOOH 2-x。去质子化反应是可逆的和电位依赖性的，即，Ni ~（4+）的量随外加电位的增加而增加。理论计算表明，Ni ~（4+）的作用是引发氧化态氧离子作为亲电中心，随后激活阴离子氧化还原反应，从而实现OER。
Developing highly efficient oxygen evolution reaction (OER) catalysts and understanding their activity are pivotal for electrochemical conversion technologies. Here, we report NiFe Prussian blue analogue (PBA) as a promising electrocatalyst for OER in alkaline conditions. This material has an impressively low overpotential of 258 mV that reaches a current density of 10 mA cm(-2). Post-mortem characterization showed that the as-prepared catalyst is entirely transformed into amorphous nickel hydroxide after the electrochemical treatment, and Ni(OH)(2) acts as the active species. Operando X-ray spectroscopic studies further found that this in situ generated Ni(OH)(2) displays an unique feature that allows deprotonation under applied potential creating NiOOH2-x that contains Ni4+ ions. The deprotonation reaction is reversible and potential-dependent, i.e., the amount of Ni4+ increases with increasing applied potential. Theoretical calculations were used to show that the role of Ni4+ is to trigger oxidized oxygen ions as electrophilic centers with the subsequent activation of anion redox reactions for OER.