3D freestanding flower-like nickel-cobalt layered double hydroxides enriched with oxygen vacancies as efficient electrocatalysts for water oxidation

Economic, efficient, and stable layered double hydroxides (LDHs) based oxygen evolution reaction (OER) electrocatalysts are recognized as promising substitutions of precious catalysts. While LDHs composites suffer from low intrinsic activity, which slightly impedes their wide utilization in energy conversion. Here, we demonstrate a kind of three-dimensional (3D) freestanding flower-like NiCo-LDHs materials with abundant oxygen vacancies are synthesized for electrocatalytic OER application. Simple solvent-thermal method is conducted in ethanol-N, N-dimethylformamide (DMF) mixed solution, which owns slight etching effect to obtain 3D open structures. The as-synthesized Ni1Co1-LDHs-E1D1 composite (in which molar ratio of nickel‑cobalt and volume ratio of ethanol-DMF are both 1:1) is characterized with abundant oxygen vacancies on surface and ultrathin nanosheets morphology with large surface area. It exhibits a relatively low overpotential (260 mV) to drive the current density of 10 mA cm−2 with a low Tafel slope of 72 mV dec−1, as well as high durability in alkaline solution. This work confirms an ingenious strategy for designing 3D vacancy-rich LDHs functional electrocatalytic materials.