3D Hierarchical Co₃O₄ Twin‐Spheres with an Urchin‐Like Structure: Large‐Scale Synthesis, Multistep‐Splitting Growth, and Electrochemical Pseudocapacitors

Abstract

Novel, 3D hierarchical Co 3 O 4 twin-spheres with an urchin-like structure are produced successfully on the large scale for the fi rst time by a solvothermal synthesis of cobalt carbonate hydroxide hydrate, Co(CO 3 ) 0.5 (OH) · 0.11H 2 O, and its subsequent calcination. The morphology of the precursor, which dominates the structure of the fi nal product, evolves from nanorods to sheaf-like bundles, to fl ower-like structures, to dumbbell-like particles, and eventually to twin-spheres, accompanying a prolonged reaction time. A multistepsplitting growth mechanism is proposed to understand the formation of the 3D hierarchical twin-spheres of the precursor, based on the time effect on the morphologies of the precursor. The 3D hierarchical Co 3 O 4 twin-spheres are further used as electrode materials to fabricate supercapacitors with high specifi c capacitances of 781, 754, 700, 670, and 611 F g − 1 at current densities of 0.5, 1, 2, 4, and 8 A g − 1 , respectively. The devices also show high chargedischarge reversibility with an effi ciency of 97.8% after cycling 1000 times at a current density of 4 A g − 1 .

Ni(OH)2/RGO nanosheets constituted 3D structure for high-performance supercapacitors

“…To date, numerous transition-metal oxides/hydroxides electrode materials, such as NiO [10,11], Ni(OH) 2 [12][13][14][15], Co 3 O 4 [16], MnO 2 [17,18], have been carefully explored in the application-oriented study. In particular, Ni(OH) 2 is proved to be a promising electroactive material for the supercapacitors owing to its high theoretical specific capacitance, cost-effective, environmentally benign and high stability in alkaline electrolyte.…”

Preparation and Electrochemical Characterization of La Doping Co3O4 Super Capacitor Electrode Materials

“…2 From these pictures, the morphologies in each figures are Co 3 O 4 spheres with many folds and stripes constituted of EG or carbon calcined from EG at 300-500 o C. Obviously in the process of the formation of the spheres, similar to HMT [17], EG acts as a shaping agent coated surface of the samples to control their morphology [18]. EG not only induce to limit their structure and morphology but also help to enhance properties if EG burn and decompose into carbon.…”

Easy approach to synthesize N/P/K co-doped porous carbon microfibers from cane molasses as a high performance supercapacitor electrode material

“…[26][27][28] The preparation of self-doped N/P/K porous carbon microbers demonstrated in this study is considered to be a simpler and greener approach rather than the incorporation of external harmful dopants that are commonly described in earlier studies. The electrochemical testing of porous carbon microbers supercapacitor electrodes is performed by cyclic voltammetry (CV), galvanostatic charge-discharge and cycling durability techniques in neutral aqueous and ionic liquids/ acetonitrile electrolytes.…”