A robust water oxidation electrocatalyst from amorphous cobalt–iron bimetallic phytate nanostructures

Abstract

As the rate-limiting step in the water-splitting system, the oxygen evolution reaction (OER) is restricted by sluggish kinetics. Therefore, highly efficient and earth-abundant catalysts are required to lower the anodic overpotential and accelerate the reaction rate. In this study, we developed a cobalt–iron phytate (Co–Fe–phy) nanoparticle oxygen-evolving electrocatalyst that possesses a great degree of amorphization, nanoporous structure and large electrochemically active surface area. These merits with the addition of the synergistic interaction between metals and phytate most probably lead to a superior activity. It can be noted that this catalyst displays a low overpotential of 278 mV to reach a 10 mA cm⁻² current density and a small Tafel slope of 34 mV dec⁻¹ in 1 M KOH, of which the performance exceeds commercial RuO₂. Moreover, its exceptional durability was evaluated with the current density decreases approximately 5.6% after 10 h when compared to the initial value. More significantly, Co–Fe–phy as an anode shows a decrease in energy consumption in the practical hydrogen production configuration when compared with RuO₂ and a commercial electrolyzer. This study not only highlights that the bimetallic phytate-based-catalyst owns extraordinary performance that a monometallic system can hardly reach, but also enables it as an extremely promising catalyst to substitute noble metal catalysts in water electrolysis and other devices.