Enhanced surface wettability and innate activity of an iron borate catalyst for efficient oxygen evolution and gas bubble detachment

Abstract

The development of facile methods to design efficient oxygen evolution electrocatalysts for electrochemical water splitting is an on-going challenge. Not only the sluggish kinetics of oxygen evolution has to be overcome, but also the adsorption of the gas bubble product which significantly contributes towards the energy consumption in water splitting. Here, we report an amorphous iron borate film deposited on nickel foam with significant catalytic activity and surface wettability which enables fast gas bubble dissipation. Through exposing a highly hydrophilic electrocatalyst surface via borate functionalization and the inclusion of Fe active sites, a low-adhesion oxygen evolution electrode with a porous and roughened surface, exhibiting significantly improved mass transfer and outstanding performance compared to unfunctionalized iron and iron hydroxide systems, is prepared. The proposed electrocatalyst shows strong oxygen evolution behavior by delivering current densities of 20 and 100 mA cm⁻² at small overpotentials of 232 and 268 mV in 1.0 M KOH, respectively. The proposed electrode also displays good durability in particular at large current densities where vigorous gas bubble evolution occurs.