Facile synthesis of two-dimensional (2D) nanoporous NiO nanosheets from metal–organic frameworks with superior capacitive properties

Abstract

In this work, we demonstrate the design and fabrication of porous nickel oxide nanosheets (NiO NSs). The Ni-based intermediates (Ni(H₂O)₂[Ni(CN)₄]·XH₂O) are first prepared via an easy, environmentally friendly, and room temperature solution route. NiO NSs with well preserved morphology are then obtained by annealing treatment of Ni-based intermediates at 300 °C in air. Due to the highly porous nanostructure, NiO NSs have a relatively high specific surface area of 118.2 m² g⁻¹. When evaluated for capacitive performance, the NiO NSs deliver a high specific capacitance of 527.1 F g⁻¹ at 1 A g⁻¹, and retain a good specific capacitance retention of about 80.2% even at a high current density of 5 A g⁻¹ after 500 charge–discharge cycles.