Zhao Yonggui, Wan Wenchao, Erni Rolf, Pan Long, Patzke Greta R
Department of Chemistry, University of Zurich, Winterthurerstrasse 190, CH-8057, Zurich, Switzerland.
Department of Heterogeneous Reactions, Max Planck Institute for Chemical Energy Conversion, D-45470, Mülheim an der Ruhr, Germany.
Angew Chem Int Ed Engl. 2024 Jun 10;63(24):e202400048. doi: 10.1002/anie.202400048. Epub 2024 May 7.
Metal-based chalcogenides exhibit great promise for overall water splitting, yet their intrinsic catalytic reaction mechanisms remain to be fully understood. In this work, we employed operando X-ray absorption (XAS) and in situ Raman spectroscopy to elucidate the structure-activity relationships of low-crystalline cobalt sulfide (L-CoS) catalysts toward overall water splitting. The operando results for L-CoS catalyzing the alkaline hydrogen evolution reaction (HER) demonstrate that the cobalt centers in the bulk are predominantly coordinated by sulfur atoms, which undergo a kinetic structural rearrangement to generate metallic cobalt in S-Co-Co-S moieties as the true catalytically active species. In comparison, during the acidic HER, L-CoS undergoes local structural optimization of Co centers, and H production proceeds with adsorption/desorption of key intermediates atop the Co-S-Co configurations. Further operando characterizations highlight the crucial formation of high-valent Co species in L-CoS for the alkaline oxygen evolution reaction (OER), and the formation of such active species was found to be far more facile than in crystalline CoO and Co-LDH references. These insights offer a clear picture of the complexity of active species and site formation in different media, and demonstrate how their restructuring influences the catalytic activity.
基于金属的硫族化物在全水解方面展现出巨大潜力，但其内在催化反应机制仍有待充分理解。在这项工作中，我们采用原位X射线吸收光谱（XAS）和原位拉曼光谱来阐明低结晶度硫化钴（L-CoS）催化剂在全水解反应中的结构-活性关系。L-CoS催化碱性析氢反应（HER）的原位结果表明，体相中的钴中心主要由硫原子配位，这些硫原子会发生动力学结构重排，在S-Co-Co-S部分生成金属钴，作为真正的催化活性物种。相比之下，在酸性HER过程中，L-CoS的钴中心会进行局部结构优化，析氢过程通过关键中间体在Co-S-Co构型上的吸附/脱附进行。进一步的原位表征突出了L-CoS中高价钴物种在碱性析氧反应（OER）中的关键形成过程，并且发现这种活性物种的形成比结晶态的CoO和Co-LDH参比物要容易得多。这些见解清晰地展现了不同介质中活性物种和活性位点形成的复杂性，并说明了它们的结构重组如何影响催化活性。
