Saveleva Viktoriia A, Ebner Kathrin, Ni Lingmei, Smolentsev Grigory, Klose Daniel, Zitolo Andrea, Marelli Elena, Li Jingkun, Medarde Marisa, Safonova Olga V, Nachtegaal Maarten, Jaouen Frédéric, Kramm Ulrike I, Schmidt Thomas J, Herranz Juan
Paul Scherrer Institut, Forschungsstrasse 111, 5232, Villigen PSI, Switzerland.
Technische Universität Darmstadt, Department of Chemistry and Department of Materials- and Earth Sciences, Otto-Berndt-Strasse 3, 64287, Darmstadt, Germany.
Angew Chem Int Ed Engl. 2021 May 17;60(21):11707-11712. doi: 10.1002/anie.202016951. Epub 2021 Apr 12.
The commercial success of the electrochemical energy conversion technologies required for the decarbonization of the energy sector requires the replacement of the noble metal-based electrocatalysts currently used in (co-)electrolyzers and fuel cells with inexpensive, platinum-group metal-free analogs. Among these, Fe/N/C-type catalysts display promising performances for the reduction of O or CO , but their insufficient activity and stability jeopardize their implementation in such devices. To circumvent these issues, a better understanding of the local geometric and electronic structure of their catalytic active sites under reaction conditions is needed. Herein we shed light on the electronic structure of the molecular sites in two Fe/N/C catalysts by probing their average spin state with X-ray emission spectroscopy (XES). Chiefly, our in situ XES measurements reveal for the first time the existence of reversible, potential-induced spin state changes in these materials.
能源部门脱碳所需的电化学能量转换技术要取得商业成功，就需要用价格低廉、不含铂族金属的类似物替代目前在（共）电解槽和燃料电池中使用的贵金属基电催化剂。其中，Fe/N/C型催化剂在氧或一氧化碳还原反应中表现出了良好的性能，但其活性和稳定性不足，阻碍了它们在这类装置中的应用。为了解决这些问题，需要更好地了解其催化活性位点在反应条件下的局部几何结构和电子结构。在此，我们通过用X射线发射光谱（XES）探测两种Fe/N/C催化剂的平均自旋态，揭示了其分子位点的电子结构。主要地，我们的原位XES测量首次揭示了这些材料中存在可逆的、电位诱导的自旋态变化。
