Synergistic action of Co-Fe layered double hydroxide electrocatalyst and multiple ions of sea salt for efficient seawater oxidation at near-neutral pH

Seawater splitting to produce hydrogen and oxygen is compelling but greatly challenging because of the impurity of seawater and the low activity of the existing catalysts. In the present work, Co-Fe layered double hydroxide (Co-Fe LDH) nanoparticles are synthesized by separate nucleation and aging steps, and investigated as electrocatalysts for seawater oxidation at near-neutral pH. Co-Fe LDH loaded onto a Ti-mesh electrode shows high electrocatalytic activity (a current density of 10 mA cm−2 at 530 mV overpotential) and good selectivity for the oxygen evolution reaction at pH 8 in seawater. Furthermore, no additional buffered electrolytes are required, and the catalyst displays an acceptable stability for a diurnal cycle (8 h day−1) under the given operating conditions. The possible mechanism for the enhanced performance is also explored. The synergistic action of Co-Fe LDH and multiple ions of sea salt is proposed. The combination of the electrochemical metrics and the facile and cost-effective synthesis make the Co-Fe LDH as a promising catalyst for a viable renewable energy storage technology.