Facile one-pot synthesis of 2D vanadium-doped NiCl(OH) nanoplates assembled by 3D nanosheet arrays on Ni foam for supercapacitor application

Herein, the 2D NiCl(OH) nanosheets and 2D V-doped NiCl(OH) nanoplates assembled by 3D nanosheet arrays supported on nickel foam have been successfully synthesized by a facile one-pot hydrothermal reaction. The dependences of the microstructure and electrochemical performance on hydrothermal reaction time and reactant concentration were investigated, and the electrochemical performance was optimized at 12 h and C_Ni²⁺ = 0.15 mM. A series of characterization results reveal that the as-prepared V-doped NiCl(OH) nanoplate arrays are successfully grown on nickel foam, and these nanoplates are composed of interconnected ultrathin nanosheets. The thickness of the as-obtained nanosheets increases with increasing reaction time, and the thickness of the optimized nanosheets is about ~20 nm. Vanadium dopant is used as the template agent to alter the morphology of NiCl(OH) nanosheet arrays and form the V-doped NiCl(OH) nanoplate arrays, then leading to a higher specific surface area and lower charge transfer resistance. The cost-effective, binder-free and optimized V-doped NiCl(OH) delivers the high specific capacitances of 2753.3 and 1470.0 F g⁻¹ at the current densities of 1 and 30 mA cm⁻², respectively. Meanwhile, an asymmetric supercapacitor is constructed with the optimized V-doped NiCl(OH) sample as the positive electrode and activated carbon as the negative electrode. The fabricated device can exhibit a high energy densities of 45.5 W h kg⁻¹ at the power density of 799.5 W kg⁻¹ in the voltage window of 0–1.6 V. The efficient electrochemical performance of 3D V-doped NiCl(OH) nanoplate arrays makes it a favorable candidate for supercapacitor electrode material.