Self-Assembled 3D Flower-Like Nickel Hydroxide Nanostructures and Their Supercapacitor Applications

Three-dimensional (3D) nanostructures have attracted considerable attention because of their high surface areas and unique properties which gives outstanding performance in catalysis and energy storage applications. This paper proposes the growth mechanism of 3D flower-like β-Ni(OH)2 constructed through a two dimensional sheet framework using a one-step oleylamine-assisted solvothermal approach, where oleylamine acts as the surfactant, co-solvent, stabilizer, and reducing agent. A detailed examination of the product morphology after various reaction times suggested that the self-assembly of flower occurs through a mechanism involving nucleation, Ostwald ripening, and recrystallization. The associated characterization revealed it to be pure β-Ni(OH)2 without any sign of contamination. The effect of the morphology (sheet to 3D flower-like β-Ni(OH)2) on the electrochemical supercapacitive behavior was assessed by cyclic voltammetry and galvanostatic charge-discharge tests. The results showed that 3D flower-like β-Ni(OH)2 exhibited better specific capacitance of ~1567 F g(-1) at a current density of 1 A g(-1) and retained ~25% capacitance at a high current density of 10 A g(-1) compared to the other reference materials. The superior electrochemical properties of the 3D flower-like β-Ni(OH)2 originate from their large specific surface area and unique structure.