Ascorbic-acid-assisted growth of high quality M@ZnO: a growth mechanism and kinetics study

Abstract

We present a general route for synthesizing M@ZnO nanoparticles (NPs) by using ascorbic acid (AA) to induce deposition of ZnO on various shaped and structured cationic-surfactant-capped NP surfaces (noble, magnetic, semiconductor, rod-like, spherical, cubic, dendrite, alloy, core@shell). The results show that the complexing (AA and Zn(2+)) and cooperative effects (AA and CTAB) play important roles in the formation of polycrystalline ZnO shells. Besides, the growth kinetics of M@ZnO was systematically studied. It was found that the slow growth rate favors the successful formation of uniform core@ZnO NPs with relatively loose shells. An appropriate growth rate allows achieving high quality M@ZnO NPs with dense shells. However, very fast growth causes significant additional nucleation and the formation of pure ZnO NPs. This general method is suitable for preparing M@ZnO using seed NPs prepared in both water and organic phases. It might be an alternative route for functionalizing NPs for bioapplications (ZnO is biocompatible), modulating material properties as designed, or synthesizing template materials for building other nanostructures.

Construction of novel hybrid PdO–ZnO p–n heterojunction nanostructures as a high-response sensor for acetaldehyde gas

“…This electrostatic attraction between the [AA-ZnIJOH) 4 ] 2− complex and the CTAB molecules went on further and eventually formed net-like chains centered around Pd NPs. 32,33 CTAB and AA behaved as templates, helped to stabilize the core and shell materials, and also helped to obstruct the continual growth of the ZnO shell. Finally, a dense ZnO shell around the Pd NPs was formed after the mixture solution was heated and aged for a long time, due to hydroxyl condensation reactions.…”

“…Finally, a dense ZnO shell around the Pd NPs was formed after the mixture solution was heated and aged for a long time, due to hydroxyl condensation reactions. 32 The morphology and structural characterization of the prepared pristine ZnO NSs and Pd@ZnO CSNSs was carried out in detail by TEM, STEM, SAED, and HR-TEM observations. The TEM image in Fig.…”

Thermal pyrolysis of Si@ZIF-67 into Si@N-doped CNTs towards highly stable lithium storage

“…Si@ZnO was synthesized according to previous report [30]. A 600 mg of silicon powder (Innochem, 99.9% metals basis, 30 nm) was ultrasonically dispersed in 150 mL ethanol solution for 15 min, before the addition of 3 g cetrimonium bromide (CTAB, Innochem, 99%), and then the solution was constantly stirred for 24 h at ambient temperature to form hydrophilic silicon particles which were harvested by centrifugation at 8500 r min À1 for 3 min.…”

Facile Synthesis of Upconverting Nanoparticles/Zinc Oxide Core–Shell Nanostructures with Large Lattice Mismatch for Infrared Triggered Photocatalysis

“…Then, the as‐prepared UCNPs@AA‐[Zn(OH) 4 ] 2− complex core–shell nanoparticles were sintered at 350 °C for 2 h, and the UCNPs@ZnO core–shell nanoparticles are obtained. In this method, l ‐ascorbic acid (AA) and zinc ions form the AA‐Zn(II) complex in the first step, and subsequently with the increase of pH value, formation of AA‐[Zn(OH) 4 ] 2− complex owing to decomposition of hexamethylenetetramine (HMTA) at 85 °C . Therefore, the formed AA‐[Zn(OH) 4 ] 2− complex should be deposited on the surface of UCNPs to form UCNPs@AA‐[Zn(OH) 4 ] 2− complex core–shell nanostructures.…”