State Key Laboratory of Fine Chemicals, Frontiers Science Center for Smart Materials Oriented Chemical Engineering, School of Chemical Engineering, Dalian University of Technology, Dalian, 116024, P. R. China.
Laboratory of Materials Modification by Laser, Ion and Electron Beams, Ministry of Education, Dalian University of Technology, Dalian, 116024, P. R. China.
Adv Mater. 2023 Feb;35(6):e2209307. doi: 10.1002/adma.202209307. Epub 2022 Dec 19.
The regulation of atomic and electronic structures of active sites plays an important role in the rational design of oxygen evolution reaction (OER) catalysts toward electrocatalytic hydrogen generation. However, the precise identification of the active sites for surface reconstruction behavior during OER remains elusive for water-alkali electrolysis. Herein, irreversible reconstruction behavior accompanied by copper dynamic evolution for cobalt iron layered double hydroxide (CoFe LDH) precatalyst to form CoFeCuOOH active species with high-valent Co species is reported, identifying the origin of reconstructed active sites through operando UV-Visible (UV-vis), in situ Raman, and X-ray absorption fine-structure (XAFS) spectroscopies. Density functional theory analysis rationalizes this typical electronic structure evolution causing the transfer of intramolecular electrons to form ligand holes, promoting the reconstruction of active sites. Specifically, unambiguous identification of active sites for CoFeCuOOH is explored by in situ O isotope-labeling differential electrochemical mass spectrometry (DEMS) and supported by theoretical calculation, confirming mechanism switch to oxygen-vacancy-site mechanism (OVSM) pathway on lattice oxygen. This work enables to elucidate the vital role of dynamic active-site generation and the representative contribution of OVSM pathway for efficient OER performance.
活性位原子和电子结构的调节在合理设计用于电催化析氢的氧析出反应 (OER) 催化剂方面起着重要作用。然而，对于水-碱电解，精确识别表面重构行为的活性位仍然难以捉摸。在此，报道了钴铁层状双氢氧化物 (CoFe LDH) 前催化剂不可逆重构行为伴随着铜的动态演变，形成具有高价钴物种的 CoFeCuOOH 活性物种，通过原位紫外可见 (UV-vis)、原位拉曼和 X 射线吸收精细结构 (XAFS) 光谱学来确定重构活性位的起源。密度泛函理论分析合理化了这种典型的电子结构演变，导致分子内电子转移形成配体空穴，从而促进活性位的重构。具体而言，通过原位 18O 同位素标记差分电化学质谱 (DEMS) 对 CoFeCuOOH 的活性位进行了明确的鉴定，并得到了理论计算的支持，证实了晶格氧上氧空位-位机制 (OVSM) 途径的机理转换。这项工作阐明了动态活性位生成的重要作用和 OVSM 途径对高效 OER 性能的代表性贡献。
