Engineering hierarchical CoSe/NiFe layered-double-hydroxide nanoarrays as high efficient bifunctional electrocatalyst for overall water splitting.

Exploitation of earth-abundant, cost-effective and high-efficient bifunctional electrocatalysts for overall water spitting in basic media is highly desirable, yet it remains a big challenge. Here, NiFe Layered-double-hydroxide nanosheet-anchored CoSe nanotubes (composed of plicated nanosheets) supported on Ni foam are prepared through our developed hydrothermal-selenization-hydrothermal method. Benefiting from the unique nanoarchitecture, optimized adsorption/desorption of oxygenated species at the interface (owing to the re-delocalization of electron spin status via π-donation), the bifunctional hybrid catalysts exhibit low overpotentials of 201 and 98 mV at 10 mA cm−2 for oxygen evolution reaction and hydrogen evolution reaction in 1 M KOH aqueous solution, respectively. Particularly, the full-cell only requires 1.53 V to drive a current density of 10 mA cm−2 when choosing the hybrid catalysts serving as both anode and cathode, being superior than that of the state-of-the-art commercial noble-metal based cells for overall water splitting. This work presents a general strategy to boost the oxygen evolution reaction and hydrogen evolution reaction kinetics of selenides, which is also expected to extend to other noble-metal-free catalysts. Image 1 • A three-step strategy was developed for synthesis of CoSe@NiFe-LDH electrocatalyst. • Re-localization of electron spin status was occurred at the interface. • The constructed full-cell requires 1.53 V to drive a current density of 10 mA cm−2. • CoSe@NiFe-LDH electrocatalysts exhibit both splendid OER and HER activities. [ABSTRACT FROM AUTHOR]