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Evolving Highly Active Oxidic Iron(III) Phase from Corrosion of Intermetallic Iron Silicide to Master Efficient Electrocatalytic Water Oxidation and Selective Oxygenation of 5‐Hydroxymethylfurfural
Author(s) -
Hausmann J. Niklas,
BeltránSuito Rodrigo,
Mebs Stefan,
Hlukhyy Viktor,
Fässler Thomas F.,
Dau Holger,
Driess Matthias,
Menezes Prashanth W.
Publication year - 2021
Publication title -
advanced materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.707
H-Index - 527
eISSN - 1521-4095
pISSN - 0935-9648
DOI - 10.1002/adma.202008823
Subject(s) - materials science , intermetallic , electrocatalyst , silicide , chemical engineering , alloy , redox , inorganic chemistry , silicon , metallurgy , electrochemistry , chemistry , electrode , engineering
In a green energy economy, electrocatalysis is essential for chemical energy conversion and to produce value added chemicals from regenerative resources. To be widely applicable, an electrocatalyst should comprise the Earth's crust's most abundant elements. The most abundant 3d metal, iron, with its multiple accessible redox states has been manifold applied in chemocatalytic processes. However, due to the low conductivity of Fe III O x H y phases, its applicability for targeted electrocatalytic oxidation reactions such as water oxidation is still limited. Herein, it is shown that iron incorporated in conductive intermetallic iron silicide (FeSi) can be employed to meet this challenge. In contrast to silicon‐poor iron–silicon alloys, intermetallic FeSi possesses an ordered structure with a peculiar bonding situation including covalent and ionic contributions together with conducting electrons. Using in situ X‐ray absorption and Raman spectroscopy, it could be demonstrated that, under the applied corrosive alkaline conditions, the FeSi partly forms a unique, oxidic iron(III) phase consisting of edge and corner sharing [FeO 6 ] octahedra together with oxidized silicon species. This phase is capable of driving the oxyge evolution reaction (OER) at high efficiency under ambient and industrially relevant conditions (500 mA cm −2 at 1.50 ± 0.025 V RHE and 65 °C) and to selectively oxygenate 5‐hydroxymethylfurfural (HMF).