Abstract
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.
Highlights
Supercapacitors or electrochemical capacitors have attracted considerable attention for novel energy storage devices because they can immediately provide a higher power density with simultaneously shorter charging times than batteries, and a higher energy density than conventional dielectric capacitors[1,2,3,4]
This paper reports a simple, cost effective, one-step oleylamine-assisted solvothermal approach for the synthesis of 3D flower-like β-Ni(OH)[2], where oleylamine acts as the surfactant, co-solvent, stabilizer, and reducing agent
During the experiment the samples were collected at different time intervals and the morphological changes was carried out by scanning electron microscope (SEM) and transmission electron microscopy (TEM) analysis
Summary
Supercapacitors or electrochemical capacitors have attracted considerable attention for novel energy storage devices because they can immediately provide a higher power density with simultaneously shorter charging times than batteries, and a higher energy density than conventional dielectric capacitors[1,2,3,4]. Many studies have searched for alternative inexpensive electrode materials with good capacitive features, such as NiO, CoOx, Mn3O4, MnO2, CuO, Co(OH)[2], and Ni(OH)[] Among these metal oxides, Ni(OH)[2] has attracted more attention as an electrode material in energy and power storage devices, for supercapacitors, because of its unique physical and chemical properties, such as natural abundance, high theoretical surface area, low cost, and well-defined electrochemical redox behavior[7,10,11]. Self-assembled micro/nano three-dimensional (3D) structures as electrode materials are some of the best systems in the area of supercapacitors[13,14]. The development of a feasible and facile approach to manufacture morphology-controlled 3D flower-like β-Ni(OH)[2] structures consisting of a low-dimensional building block is desired. The excellent capacitance of the 3D flower-like β-Ni(OH)[2] was attributed to a 3D flower-like structure, which provides a high surface area and shorter conduction length for electrolytic ions
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