Mesoporous Co₃O₄ and CoO@C Topotactically Transformed from Chrysanthemum‐like Co(CO₃)_0.5(OH)·0.11H₂O and Their Lithium‐Storage Properties

Abstract

In this work, a novel hydrothermal route is developed to synthesize cobalt carbonate hydroxide, Co(CO3)0.5(OH)·0.11H2O. In this method, sodium chloride salt is utilized to organize single‐crystalline nanowires into a chrysanthemum‐like hierarchical assembly. The morphological evolution process of this organized product is investigated by examining different reaction intermediates during the synthesis. The growth and thus the final assembly of the Co(CO3)0.5(OH)·0.11H2O can be finely tuned by selecting preparative parameters, such as the molar ratio of the starting chemicals, the additives, the reaction time and the temperature. Using the flower‐like Co(CO3)0.5(OH)·0.11H2O as a solid precursor, quasi‐single‐crystalline mesoporous Co3O4 nanowire arrays are prepared via thermal decomposition in air. Furthermore, carbon can be added onto the spinel oxide by a chemical‐vapor‐deposition method using acetylene, which leads to the generation of carbon‐sheathed CoO nanowire arrays (CoO@C). Through comparing and analyzing the crystal structures, the resultant products and their high crystallinity can be explained by a sequential topotactic transformation of the respective precursors. The electrochemical performances of the typical cobalt oxide products are also evaluated. It is demonstrated that tuning of the surface texture and the pore size of the Co3O4 products is very important in lithium‐ion‐battery applications. The carbon‐decorated CoO nanowire arrays exhibit an excellent cyclic performance with nearly 100% capacity retention in a testing range of 70 cycles. Therefore, this CoO@C nanocomposite can be considered to be an attractive candidate as an anode material for further investigation.

Co3O4 nanosheet-built hollow dodecahedrons via a two-step self-templated method and their multifunctional applications

“…These results correspond to the large Co 3 O 4 grains at a high calcination temperature. As is known, decreasing the grain size of the gas sensing film can improve the gas sensing response of p-type semiconductors [37]. The Co 3 O 4 NSHDs obtained at 300°C calcination temperature composed of numerous ultrafine grains may exhibit enhanced sensing performances.…”

How to improve the stability and rate performance of lithium-ion batteries with transition metal oxide anodes

“…[84][85][86] In the anodic process, broad peaks located at around 2.15 V can be ascribed to the reversible oxidation reaction from cobalt to Co 3 O 4 . 78 The total electrochemical reaction mechanism of Co 3 O 4 anode can be described by the following electrochemical conversion reaction 87 :…”

“…It is obvious that the Co 3 O 4 @C@PGC electrode still needs ten more cycles to activate all active materials for its reversible capacity increases with cycle number until the 11th cycle. 27,87 Meanwhile, the Co 3 O 4 @C composite electrode shows a stable capacity as tested at 1C. The reversible capacity of the Co 3 O 4 @C@PGC nanosheets electrode reaches a very high value of 1105 mA h/g at the 11th cycle, 78,93 while the Co 3 O 4 @C composite electrode maintains a reversible capacity of 502 mA h/g during these cycles.…”

“…In the initial 20 cycles, the specific capacity gradually increases up to 820 mA h/g, corresponding to a process of activating the active substance, which is common in the literature. 27,87 It is striking to note that the specific capacity can remain as high as 760 mA h/g even after 1000 cycles. Firstly, the well-graphitized carbon shells firmly cover Co 3 O 4 NPs and integrate into PGC nanosheets.…”

TWO-DIMENSIONAL NANOSHEETS-ASSEMBLED FLOWER-LIKE Co3O4 MICROSPHERES AND THEIR GAS SENSING PERFORMANCES

“…[11][12][13][14][15] Numerous e®orts have been devoted to the morphology-controlled synthesis of 3D Co 3 O 4 micro/ nanostructured architectures. [16][17][18][19][20][21] For example, Xiong et al 16 reported the synthesis of chrysanthemum-like Co 3 O 4 from the assembly of single-crystalline nanowires via a hydrothermal method followed by calcinations. Zhang et al 17 synthesized porous 3D Co 3 O 4 nanodendrites made of nanorods via a simple one-pot hydrothermal method combined with subsequent calcination.…”