[en] Highlights: : • One-step synthesis of N-doped carbon quantum dots hybridized NiFe-LDH of 1.4 nm thickness. • The BET surface area of the products was 226.7 m² g⁻¹. • The overpotential is 363 mV at large current density of 500 mA cm⁻². • NCD@NiFe-LDH shows excellent durability and stability at 1000 mA cm⁻². -- Abstract: : Herein, we have developed a one-step ionothermal accompanied thermolysis strategy based on metal chloride deep eutectic solvent (DES) precursors to synthesize NiFe layered double-hydroxide ultrathin nanosheets hybridized with N-doped carbon quantum dots (NCD@NiFe-LDH). The NCD@NiFe-LDH hybrid shows hierarchical three-dimensional flower-like morphology assembled with ~1.4 nm ultrathin nanosheets possessing higher surface area values and well conductivity. The as-synthesized NCD@NiFe-LDH hybrid exhibits excellent performance for oxygen evolution reaction (OER) and just require 363 mV to achieve a higher current density of 500 mA cm⁻² compared to the state-of-the-art IrO₂ in 0.1M KOH. Besides, NCD@NiFe-LDH hybrid shows long-term stability and satisfactory durability even at 1000 mA cm⁻². Such an excellent OER performance at high current density can be ascribed to the unique porous ultrathin structure with abundant active edges and sites and the synergistic effect of the NCD and NiFe-LDH. The work offers a new way for the design and synthesis of other carbon-hybridized LDH ultrathin nanosheets with unique electrochemical properties.