中国科学院大连化物所章福祥研究团队报道了X射线吸收和Mssbauer光谱的原位分析Fe，V双金属电催化剂上高价铁作为水氧化的高活性物种。相关研究成果于2023年5月25日发表于国际顶尖学术期刊《美国化学会杂志》。

铁（Fe）基双金属氧化物/氢氧化物已被广泛研究用于有前景的碱性电化学析氧反应（OERs），但Fe³⁺或Fe⁴⁺中间体是否对有效的OER具有高活性仍存在争议。

该文中，研究人员采用OER惰性V元素作为促进剂，完全避免了真正活性金属的争论，并以最近开发的一维导电磷化镍（NP）为载体，合理地设计和制备了一种Fe，V基双金属复合纳米片。所获得的分级纳米复合材料（表示为FeVOx/NP）被评估为模型催化剂，通过进行原位X射线吸收光谱和57Fe-Mssbauer光谱测量来深入了解作为高活性OER位点的铁基物种。研究发现，高价Fe⁴⁺物种只能在FeVOx/NP纳米复合材料的OER过程中检测到，而不是铁对应物本身。再加上钒和铁对应物的OER活性远不如FeVOx/NP复合物，研究证实所形成的高价Fe⁴⁺是高效OER的高活性物种。

正如密度泛函理论模拟所证明的那样，Fe和V金属的复合物被认为相对于其对应物导致水氧化的吉布斯自由能和理论超电势降低，其优异的OER性能具有极低的OER过电位（在500 mA cm^–2时为290 mV）和非凡的稳定性（在100 mA cm^–2中为1000 h）。

附：英文原文

Title: Confirming High-Valent Iron as Highly Active Species of Water Oxidation on the Fe, V-Coupled Bimetallic Electrocatalyst: In Situ Analysis of X-ray Absorption and Mssbauer Spectroscopy

Author: Rashid Mehmood, Wenjun Fan, Xu Hu, Jiangnan Li, Peijia Liu, Yashi Zhang, Zhen Zhou, Junhu Wang, Min Liu, Fuxiang Zhang

Issue&Volume: May 25, 2023

Abstract: Iron (Fe)-based bimetallic oxides/hydroxides have been widely investigated for promising alkaline electrochemical oxygen evolution reactions (OERs), but it still remains argumentative whether Fe3+ or Fe4+ intermediates are highly active for efficient OER. Here, we rationally designed and prepared one Fe, V-based bimetallic composite nanosheet by employing the OER-inert V element as a promoter to completely avoid the argument of real active metals and using our recently developed one-dimensional conductive nickel phosphide (NP) as a support. The as-obtained hierarchical nanocomposite (denoted as FeVOx/NP) was evaluated as a model catalyst to gain insight into the iron-based species as highly active OER sites by performing in situ X-ray absorption spectroscopy and 57Fe Mssbauer spectroscopy measurements. It was found that the high-valent Fe4+ species can only be detected during the OER process of the FeVOx/NP nanocomposite instead of the iron counterpart itself. Together with the fact that the OER activities of both the vanadium and iron counterparts are by far worse than that of the FeVOx/NP composite, we can confirm that the high-valent Fe4+ formed are the highly active species for efficient OER. As demonstrated by density functional theory simulations, the composite of Fe and V metals is proposed to cause a decreased Gibbs free energy as well as theoretical overpotential of water oxidation with respect to its counterparts, as is responsible for its excellent OER performance with extremely low OER overpotential (290 mV at 500 mA cm–2) and extraordinary stability (1000 h at 100 mA cm–2).

DOI: 10.1021/jacs.3c02288

Source: https://pubs.acs.org/doi/10.1021/jacs.3c02288