In and Ex Situ Studies of the Formation of Layered Microspherical Hydrozincite as Precursor for ZnO

Abstract

Layered ZnO microspheric particles were prepared by the thermal decomposition of layered hydrozincite (LZnHC), which was synthesized from zinc nitrate and urea in a water/PEG400 mixture. The influence of the starting reagents, their concentrations, and the amount of PEG in the water/PEG400 mixture on the particle growth was observed. The chemical aspect of the particle growth was proposed in the frame of the partial charge model (PCM), and the formation of [Zn(OH)(2)(OH(2))(4)](0) and [Zn(OH)(HCO(3))(OH(2))(3)](0) was predicted for the solid phase. The assumed growth mechanism, which follows the "nonclassical crystallization" concept of a self-assembling mechanism, was observed in situ by small-angle X-ray scattering (SAXS) and predicts the rapid formation of approximately 6 nm sized building units. The size of these nano building units, stable only in the reaction medium, remains nearly constant during the synthesis, as the concentration of the nano building units increases throughout the reaction. The nano building units connect into leaves of LZnHC with a thickness of 20 nm. These leaves of LZnHC are further agglomerated into porous, microsphere-like particles with sizes up to 4 μm.

Hierarchical 3D ZnO nanowire structures via fast anodization of zinc

“…The route to zinc hydroxy carbonate formation in aqueous solutions has been previously discussed by Orel et al on the basis of a partial charge model. 29 At the cathode 2H + + 2e -→ H 2(g) (6) Condensation rates via the olation mechanism can proceed rapidly, sometimes being only limited by diffusion. 31 As we have good mixing due to stirring we can assume that this reaction is not mass transfer limited, leading to rapid nanowire growth.…”

Understanding the Correlation of Crystal Atoms with Photochemistry Property: Zn5(OH)6(CO3)2vs. ZnCO3

“…The Zn−O bond has shorten a bit, while the C−O bond length (1.34 Å) of Zn 5 (OH) 6 (CO 3 ) 2 is longer than that (1.286 Å) of ZnCO 3 . It seems that the presence of hydroxyl anion has changed the chemical bonds properties, probably resulting in the different photocatalytic properties …”

Correlation of Defect‐Related Optoelectronic Properties in Zn5(OH)6(CO3)2/ZnO Nanostructures with Their Quasi‐Fractal Dimensionality

“…One can see a relative constancy of the ZnO-related emission, whereas the intensity of the blue hydrozincite emission band is reduced by almost 20%. It is well known that annealing of nanoscale hydrozincite leads to its transformation into ZnO [10][11][12][13][14][15][16][17] so local heating produced by the laser beam may contribute to partial reduction of the relative abundance of the hydrozincite phase. Time dependence shown in Figure 7 was observed consistently for all other samples (not shown).…”

“…The scope of the reported methods to fabricate ZnO nanostructures is truly remarkable and grows by the day. One of these many methods is a procedure based on converting precursor hydrozincite (Zn 5 (OH) 6 (CO 3 ) 2 ) nanostructures into ZnO nanocrystals [10][11][12][13][14][15][16][17]. In particular, this technique was shown to be effective for producing nanoporous nanoscale ZnO useful in potential solar cells [3], as well as photocatalytic and gas sensing applications [15,16,18,19].…”