Oriented Morphogenesis of ZnO Nanostructures from Water‐Soluble Zinc Salts under Environmentally Mild Conditions and Their Optical Properties

Abstract

Herein, we report a bottom-up, mineralization strategy, which borrows key principles from biomineralization processes, to synthesize nanostructured materials. A long-chain polyamine simultaneously mineralizes and assembles ZnO nanoparticles directly from water-soluble zinc salts under sustainable synthesis conditions. These thus-generated oriented structures undergo interesting morphogenesis that is controlled by changing the ratio of polyamine/Zn(2+) ions. As the ratio increases, the morphology changes from a spherical shape to oval-, dumbbell-, and finally hexagonal-rod-shaped structures that contain unique hollow rod structures. Using XPS, XRD, FT-IR, Raman spectroscopy, DLS, and confocal fluorescence microscopic analysis, we elucidate the mechanism of structural evolution; this mechanism involves the initial formation of a zinc/amine complex that is furnished with polyamine chains. These chains facilitate the condensation process to form ZnO nanoparticles and their assembly in aqueous medium at neutral pH. Further, the presence of defects in the thus-morphogenized ZnO structures leads to blue luminescence and efficient photoinduced activity, assisted by the surface-hole-trapping effect of polyamines.

Controlled Orientation in a Bio‐Inspired Assembly of Ag/AgCl/ZnO Nanostructures Enables Enhancement in Visible‐Light‐Induced Photocatalytic Performance

“…Mineralization of Ag/AgCl/ZnO nanostructures : As we have shown earlier, in a bio‐inspired method, positively charged simple polypeptides and related polyamines can directly mineralize and assemble ZnO nanostructures in a wet‐chemical method under “green” conditions 16. 17 The approach here is to utilize the assembling properties displayed by the polyamines to create composite structures and thus have the nanocomponents effectively interact with each other in a way that is desirable for the application envisaged. In this article we demonstrate such a nanocomposite, Ag/AgCl/ZnO, synthesized in a single step in which the polyamines act as a mineralizing, structure‐directing, and reducing agent simultaneously.…”

Controlled Assembly of a Ternary‐Component Photocatalyst: Illustrating the Importance of Interfacial‐Integration of Ag‐ZnO‐rGO in Visible‐Light‐Induced Catalytic Activity

“…So the presence of spermine was important for the formation of ZnO. As we have shown earlier, the polyamines play a crucial role via the zinc‐amine interaction, which facilitates the mineralization of ZnO nanoparticles under the mild condition . It involves hydrolysis of the zinc‐amine complex followed by condensation to produce Zn‐O−Zn linkages.…”

“…The presence of polyamine also allows directional assembly of thus generated ZnO nanoparticles to form hierarchical structures . Furthermore, since at neutral pH spermine is positively charged, it can aid in favorably bringing the negatively charged GO sheets in close proximity to the formed Ag‐ZnO particles.…”

Biomimetic Method To Assemble Nanostructured Ag@ZnO on Cotton Fabrics: Application as Self-Cleaning Flexible Materials with Visible-Light Photocatalysis and Antibacterial Activities

“…Powder XRD patterns were recorded on a Siemens (Cheshire, UK) D5000 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 Ag@ZnO. The poly(allylamine) besides its role as mineralizer for the formation of nanostructured ZnO, 24 is also known to act as a reducing agent. 27, 28 Hence its presence in the ZnO matrix facilitates the reduction of Ag(I) ions to generate Ag(0) nanoparticles (Scheme 1).…”

“…The challenge is to develop a "green" method for the coating functional materials on flexible substrates like cotton fabric enabling sufficient interfacial adhesion, smooth coating and stability. Herein, we demonstrate that effective utilization of the polyamine-mediated bio-inspired mineralization routes, 24,25 can lead to functionalization of cotton fabrics with nanostructured Ag@ZnO suitable for developing self-cleaning flexible materials (Scheme 1). Particularly, we use poly(allylamine) for the formation and coating of Ag@ZnO from a simple water-soluble zinc salt (Zn(NO 3 ) 2 ) under mild conditions.…”