Hydrothermal Synthesis of Hierarchical Nanocolumns of Cobalt Hydroxide and Cobalt Oxide

Abstract

In this paper, we report a facile method to prepare high-yield one dimensional hierarchical β-Co(OH) 2 nanocolumns through one-step hydrothermal synthesis with hydrazine hydrate and Na 3 PO 4 as morphologydirecting agents, which play important roles in the formation of hierarchical nanocolumn morphology. The hierarchical Co 3 O 4 nanocolumns are obtained by the β-Co(OH) 2 nanocolumns annealed at 400 °C for 4 h. The formation mechanism of hierarchical nanocolumns has been clearly demonstrated by studying morphology evolution processes of β-Co(OH) 2 nanocrystals upon reaction time, which undergo two steps, the formation of nanorods and then growing sideways in the form of thin nanoplatelets to form hierarchical nanocolumns. Moreover the UV-vis spectra and magnetic properties of Co 3 O 4 nanocolumns also have been investigated.

Mesoscopic architectures of Co(OH) 2 spheres with an extended array of microporous threads as pseudocapacitor electrode materials

“…A c c e p t e d M a n u s c r i p t 12 The obtained energy and power density values for the cylindrical cells were found to be 90 mWh and 395 W, respectively. Although these results seem to be promising, the main conclusion of this study can only be validated once the performances of these C-12 electrodes are evaluated at different temperatures for different discharging currents.…”

“…[11] Morphology, phase purity and particle size of cobalt hydroxide crystals affects their conductive properties and specific capacitance. It is quite known that well-defined morphologies of Co(OH) 2 nanocrystals, such as nanocolumns [12], nanowires [13], nanocones [14], and nanoflakes [15] can exhibit high capacitance values and good cycling stability when employed as supercapacitor electrodes. However as mentioned earlier, disadvantages related to agglomeration/aggregation during bulk processing still remains a challenge.…”

Tuning the Morphology of Metal Oxides for Catalytic Applications

“…[124][125][126][127][128][129][130][131][132][133][134][135] To date, hydrothermal and solvothermal treatments are still the major routes to fabricate these Co 3 O 4 superstructures. [126][127][128][129][130][131][132][133][134] Unfortunately, most of the hierarchical nanostructures consisted of arrays of interconnected particles with porous structures. [124][125][126][127][128] Although the building blocks were nanocubes, nanorods, and nanosheets with very smooth surfaces ( Figure 10.5c-h), nanosheets usually have diameters of several hundred nanometers or even several microns ( Figure 10.6).…”

“…[126][127][128][129][130][131][132][133][134] Unfortunately, most of the hierarchical nanostructures consisted of arrays of interconnected particles with porous structures. [124][125][126][127][128] Although the building blocks were nanocubes, nanorods, and nanosheets with very smooth surfaces ( Figure 10.5c-h), nanosheets usually have diameters of several hundred nanometers or even several microns ( Figure 10.6). [134][135][136][137][138][139][140][141][142][143][144][145] Hollow nanowires, nanotubes, nanoboxes, and nanocages have also been synthesized.…”

Shape-influenced magnetic properties of CoO nanoparticles

“…Various methods like hydrothermal process (Shao et al 2009), thermal decomposition (Liu et al 2008), sol-gel (Sinko et al 2011, electrochemical deposition (Meng et al 2011), and spray-pyrolysis (Jana et al 2011) have been used to fabricate CoO nanoparticles (NPs). It is difficult to prepare pure CoO due to surface oxidation of NPs that generates a mixture of Co 3 O 4 or Co metal with CoO.…”