Ordered 2D/3D CoNi-LDH/FeSe electrode for efficient and durable seawater oxidation

Abstract

The superior electrocatalysts for seawater oxygen evolution reaction (OER) require fast kinetic to promote reactant (OH−) transport and adsorption, and to optimize oxygenated intermediates (O* and OOH*) adsorption, but also high corrosion resistance by impeding Cl− adsorption under harsh seawater conditions, while the incomprehensive design greatly hinder the system advancement at high current densities. Herein, we propose orderly incorporating amorphous FeSe nanosheets as the dynamic anti-corrosion layer to reinforce charge redistribution of CoNi layered double hydroxide (LDH) nanosheets array and create favorable microenvironments. The ordered two-dimensional/three-dimensional structure prepared by novel non-equilibrium electrodeposition strategy allows amorphous FeSe component not only to activate CoNi-LDH for promoting OH− adsorption, optimizing oxygenated intermediates adsorption and increasing Cl− adsorption energy, but also repel Cl− by dynamic polyanion layer without blocking active sites, thus affording effective seawater OER with low overpotential, excellent stability and high selectivity at high current densities. The integrated CoNi-LDH/FeSe electrode delivers a small overpotential (338 mV at 500 mA cm−2) and possesses outstanding stability and selectivity during a 500-hour durability test at 500 mA cm−2 in alkaline seawater.