Morphology nanosheets

Weng et al. [113] studied the effect of tetramethylammonium cations (TMA"") on HO2 crystal morphology under hydrothermal conditions. The as-synthesized samples were characterized by XRD, TEM and SEM methods (see Table 2). The observed morphologies include besom-like particle, nanosheet and nanotubes. The mechanism to accelerate the formation of nanotube in the base of NaOH/TMAOH mixture is illustrated in Eigure 7. Bulk HO2 is first exfoliated to be layered protonic titanate by the mineralization effect of Na". In the presence of TMA"" cations, the separation of layered protonic titanate is accelerated by intercalating TMA"" cations in layered titanate. As a result of the presence of more layered titanate in the hydrothermal solution, nanotubes are formed ahead of schedule by curliness of layered titanate. Thus, the mechanism through which TMA cations affect crystal growth in the conditions of this study is different. 

Conversions of nanosheets into nanorods have been possible for metal oxides such as ZnO (44). The self-assembled nanosheets arc first prepared by a solution phase hydrothermal synthesis. The reactant solution eontains zine nitrate, hexamethylene tetra-mine and hydrazine, whieh helps in the fonnation of precursor nanosheets in an orderly fashion. At shorter time seales ( 46), nanosheets are formed and after 8 h, hollow microspheres arc formed. The nanosheets arc calcined at 400°C to get ZnO nanorods, as depicted in Figure 7.6. This is an example where one nanostmcture transforms to a completely different morphology. 

The hydrothermal synthesis of polyaniline-V205 nanocomposites with nanosheet morphology has been reported by Zhang and coworkers [34]. Reacting V2O5 powder with aniline, in the presence of water and hydrochloric acid, in an autoclave at 120°C for 24 hours resulted in the formation of polyaniline-V2O5 intercalated... 

In a different attempt made by Zhang et al. to fabricate Au NPs-graphene composites via redox reaction between Au salt solution and GO nanosheets, an aqueous solution of HAuCl was mixed with GO and subsequently the solution was heated at 84°C for 15 min. The formation of Au NPs-rGO composites and the variation of their morphology with concentration of the reactants were executed using transmission electron... 

Co-B on Ni foam support catalyst system was produced by low temperature electroless plating method. With this approach, maximum hydrogen production rate of 24 L min g at 30°C was achieved. The catalyst system was mixture of spherical particles and a thin nanosheet-like structure of 10 nm. Layered aggregates of these nanosheet-like morphologies were seen as smooth spherical particles of size 2-10 pm. Co/B ratio in the catalyst coating was 3.67 according to EDX results and 1.45 according to XPS... 

Five methods of synthesis of CNTs are (1) arc discharge, (2) laser ablation, (3) CVD, (4) the HIPCO process, and (5) surface-mediated growth of vertically aligned tubes. CNTs can have different morphologies such as SWNT, DWNT, MWNT, nanoribbon, nanosheet, nanopeapods, linear and branched CNTs, conically overlapping bamboo-like Y-shaped tubules, nanopores, nanovoids, nanowire, and nanofiber. 

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