Electrochemically Robust Ferberite (FeWO4) Nanostructure as an Anode Material for Alkaline Water- and Alcohol-Oxidation Reaction

Due to the inferior conductivity and lability to dissolution during electrocatalysis, iron catalysts lack superior electrochemical performance. However, recent studies on transition-metal oxyhydroxides depict that iron is the active site for water oxidation. Herein, a heterobimetallic ferberite iron-tungstate nanostructure has been employed as an efficient anode material not only for alkaline oxygen evolution reaction (OER) involving water and ethanol oxidation but also as a non-noble metal-based anode for overall water splitting (OWS). The presence of tungstate in the nanostructure improves the efficiency of OER, as reflected in the overpotential value of 282 (±3) mV at 10 mA cm–2 and the Tafel slope of 54 mV dec–1, which is far better compared to that of pure iron-oxyhydroxides as well as some noble metal-based catalysts. A fair activity of the FeWO4 anode further helped to construct a water electrolyzer coupled with a commercial Pt cathode, giving a cell potential of only 1.66 V to reach 10 mA cm–2 current density. The strong binding of [FeO6] with the corner- and edge-shared [WO6] presumably provides facile electron conduction as well as robustness in the structure, which results in long durability during OER and OWS. This study showcases a facile approach to design a stable anode relying on earth-abundant metal precursors, which has remained a perdurable challenge so far.