Biomimetic Arrays of Oriented Helical ZnO Nanorods and Columns

Abstract

Extended helical or chiral nanostructures are usually associated with biomolecules but are mostly absent in synthetic materials. Here we report the first synthesis of unusual oriented and extended helical nanostructures in synthetic ceramics. Large arrays of oriented helical ZnO nanorods and columns are formed using simple citrate ions to control the growth habits of the ZnO crystal. This novel mechanism could lead to new approaches to control the orientation, the surface area, and the defect structure of synthetic materials that are critical for practical applications. The morphology generated in the helical ZnO nanostructure shows remarkable resemblance to the growth morphology of nacreous calcium carbonate and thus may shed new light on morphology and orientation control of biominerals.

One-dimensional ZnO nanostructures: Solution growth and functional properties

“…Citrate ions are characterized by three negative charges under the normal growth environment. Experimental results in the literature as well as theoretical calculations suggest that citrate ions strongly and specifically adsorb to the Zn 2+ ions on the (0001) surface, and thus inhibit the growth along [0001] and forced to grow along the 〈 〉 0110 or 〈 〉 2110 directions [150,157,160]. With citrate ions, rather than long hexagonal nanowires, flat hexagonal nanoplates were produced, as shown in Fig.…”

“…(c) φ-scan profiles of the ZnO nanowires/GaN/c-sapphire structure with the family of planes of ZnO nanowires on the top, and the GaN film at the bottom [153]. Reproduced with permission side surfaces and enhance the vertical growth, such as amines like polyethylenimine (PEI) [18,155,156] and ethylenediamine [67,137]; those that cap onto the basal plane of the ZnO nanostructures and promote lateral growth, such as Cl - [124] and C 3 H 5 O(COO) 3 3− (citrate ions) [150,157,158]. The isoelectric point of ZnO powder is at around pH = 9.5 [54].…”

Hierarchical structures of ZnO spherical particles synthesized solvothermally

“…The control of the morphology of ZnO nanostructures is a popular topic in modern materials science [19][20][21][22][23][24]. A wide variety of ZnO morphologies (e.g.…”

“…The growth of inorganic materials in solutions has similarities to the formation of biominerals in the morphology and orientation control. Tian et al [19,20] reported such examples where the building blocks of ZnO hierarchical structures grown from simple aqueous solutions resemble the morphology of calcium carbonate units in nacre of red abalone shells as shown in figure 2, although the former hierarchical structure is monolithic and the latter is a composite of calcium carbonate and organic polymers.…”

Synthesis of brush-like CdS nanorod arrays through a novel hydrothermal reaction of simultaneous solvent-oxidation-hydrolysis

“…In these methods, reactions used include the direct redox reaction of Cd metal with S powders under high temperature, the direct or indirect precipitation of metal ions with Na 2 S or some other sources of S 2À ions, and the thermal decomposition of molecular precursors containing M-S bonds, etc. Though there have been some reports of nanoarrays [13][14], the preparation of 1D nanorods arrays has never been reported.…”