Heterogeneous lamellar-edged Fe-Ni(OH)2/Ni3S2 nanoarray for efficient and stable seawater oxidation

Development of efficient non-precious catalysts for seawater electrolysis is of great significance but challenging due to the sluggish kinetics of oxygen evolution reaction (OER) and the impairment of chlorine electrochemistry at anode. Herein, we report a heterostructure of Ni3S2 nanoarray with secondary Fe-Ni(OH)(2) lamellar edges that exposes abundant active sites towards seawater oxidation. The resultant Fe-Ni(OH)(2)/Ni3S2 nanoarray works directly as a free-standing anodic electrode in alkaline artificial seawater. It only requires an overpotential of 269 mV to afford a current density of 10 mA center dot cm(-2) and the Tafel slope is as low as 46 mV center dot dec(-1). The 27-hour chronopotentiometry operated at high current density of 100 mA center dot cm(-2) shows negligible deterioration, suggesting good stability of the Fe center dot Ni(OH)(2)/Ni3S2@NF electrode. Faraday efficiency for oxygen evolution is up to similar to 95%, revealing decent selectivity of the catalyst in saline water. Such desirable catalytic performance could be benefitted from the introduction of Fe activator and the heterostructure that offers massive active and selective sites. The density functional theory (DFT) calculations indicate that the OER has lower theoretical overpotential than Cl-2 evolution reaction in Fe sites, which is contrary to that of Ni sites. The experimental and theoretical study provides a strong support for the rational design of high-performance Fe-based electrodes for industrial seawater electrolysis.