Lysine-assisted hydrothermal synthesis of urchin-like ordered arrays of mesoporous Co(OH)2 nanowires and their application in electrochemical capacitors

Abstract

In the work, a novel lysine-assisted hydrothermal process is first developed to produce urchin-like ordered Co(OH) 2 arrays, which are assembled from mesoporous Co(OH) 2 nanowires. The synergistic contributions from lysine and Cl À ions to the formation of the unique arrays was also tentatively proposed. Electrochemical results show that the unique urchin-like ordered Co(OH) 2 arrays show the ability to deliver large specific capacitance and good electrochemical stability at large current densities, which is reasonably ascribed to their ordered microstructure, hierarchical (meso-and macro-) porosity and good electronic conductivity. Moreover, the method we proposed here provides a universal green chemistry approach to large-scale production of Co(OH) 2 and even other metal hydroxides oriented arrays with hierarchical porosity for fast energy storage.

Facile microwave-assisted synthesis of sheet-like cobalt hydroxide for energy-storage application: Effect of the cobalt precursors

“…The blank electrode made a 13.1% contribution to CoFN electrode, 3.2% to CoFA electrode, 1.7% to CoFC electrode and 1.5% to CoFS electrode, respectively. The theoretical capacitance of b-Co(OH) 2 was as high as 3460 F/g [8,28], but the specific capacitance of samples CoFN and CoFA were inferior. The possible reasons were that charges were stored in a pseudo-capacitor through surface or near-surface faradic reaction and both samples CoFN and CoFA with small surface area provided insufficient amount of active sites, which gave rise to sluggish electrode kinetics and inferior specific capacitance [8].…”

Synthesis and supercapacitance of flower-like Co(OH)2 hierarchical superstructures self-assembled by mesoporous nanobelts

“…The formation of β-Co(OH) 2 phase was related to the unique biomolecule L-lysine. It is well known that Llysine is an alkaline amino acid with two amino group and one carboxylic acid group due to the existence of hydrolysis process [11]. And with the increase of temperature, the hydrolysis of the L-lysine can be enhanced greatly and more OH − ions can be generated accordingly.…”

“…4a. Obviously, two pairs of redox peaks (designated as O/R and O′/R′), at various scan rates as indicated, demonstrate their typical Faradaic pseudocapacitive characteristics [9][10][11][12][13][14][15][16][17], as presented by the following two equations: Specifically, the peak O is related to the oxidation of Co (II) to Co(III)OOH, and the peak R is for the reverse process, as shown in Eq. 1.…”

“…Recently, electroactive Co (OH) 2 as a good candidate has spurred enormous research in the ECs field, because of its good electrochemical capacitance performance [9][10][11][12][13][14][15][16][17]. However, the reported SCs for Co(OH) 2 are much less than its theoretic SC of 3,650 Fg −1 [9][10][11][12][13][14][15], particularly, at high rates. The next logical strategy is exploring efficient ways to enhance the electrochemical utilization of cobalt hydroxide and enhance its SC at high rates.…”

One-step cathodic electrodeposition of a cobalt hydroxide–graphene nanocomposite and its use as a high performance supercapacitor electrode material

“…[13][14][15] In view of the fact that Co(OH) 2 , as a pseudocapacitive material, has limitations such as low conductivity and intense agglomeration during charge and discharge processes, its application as a high-performance supercapacitor material has not yet been realized. 16,17 In this regard, many researchers have attempted to overcome these limitations and boost the supercapacitor properties of Co(OH) 2 by using new methods and strategies for synthesis and modication of individual structures [18][19][20][21] or hybrid structures of Co(OH) 2 . [22][23][24][25][26] In the same vein, using carbon-based materials in combination with Co(OH) 2 is one of these strategies to take advantage of synergistic effects and to improve supercapacitor properties of Co(OH) 2 .…”