Electrochemically Robust Ferberite (FeWO<sub>4</sub>) Nanostructure as an Anode Material for Alkaline Water- and Alcohol-Oxidation Reaction
Mrinal Kanti Adak, Anubha Rajput, Laxmikanta Mallick, Biswarup Chakraborty
Abstract
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.