Facile synthesis of novel hierarchical hollow ZnO microspheres

He, Kay; Zhao, Gaoling; Han, Gaorong

doi:10.1039/c3ce42563k

Cited by 6 publications

(5 citation statements)

References 18 publications

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“…XRD patterns ( Figure 2) of three early stage samples prepared from 0 -1.5 h confirmed the time scale of the phase change in the reaction mixture. The XRD pattern of the white precipitate collected prior to thermal treatment ( Figure 2a The XRD data supports the chemical reactions reported by He et al 36 which are as follows:…”

Section: Resultssupporting

confidence: 85%

“…Despite extensive differences in morphology, these particles were observed to co-exist within samples. Although the synthetic method previously reported by He et al 36 was utilised in the present work, only the disc decorated spheres have been previously reported. The remaining three types of particles were newly observed in terms of ZnO morphology.…”

Section: Resultsmentioning

confidence: 99%

“…Preparation of ZnO Specimens. The synthetic method for ZnO was the same as that previously reported by He et al 36 The procedure involved dissolving 1.00 g of zinc acetate dihydrate (4.55 mmol, 98%, from Sigma-Aldrich) in 31 mL of ethanol, followed by addition of 0.598 g of formic acid (13 mmol, ≥95%, from Sigma-Aldrich). A white precipitate appeared immediately.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

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Formation Mechanisms of ZnO Spherulites and Derivatives

Connolly

Greer

Zhou

2018

Crystal Growth & Design

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ZnO microparticles have been solvothermally synthesized from zinc acetate and formic acid. The resulting microspherulites consist of radially arranged nanorods which undergo a range of re-crystallisation pathways to produce particles with different terminal morphologies. Crystallisation on the particle surface results in hexagonal microdisc decorated hierarchical microspheres. These particles expose only the (0001) crystallographic plane of ZnO and further develop into a sea-urchin like morphology, when the microdiscs grow up along the [0001] direction into hexagonal microrods. Alternatively, crystallisation of the particle core into a ZnO plate, facilitates asymmetric assembly of nanocrystallites, forming a hexagonal cone on one side of the plate. The particle has a mushroom-like terminal morphology. When simultaneous surface and core re-crystallisation takes place, wood gyro-shaped particles are observed, in which all the surface discs face a single direction. The microstructures of the particles were investigated using XRD, electron microscopy and surface colouring with adsorbed charged dyes. Structural studies of the early growth stages and subsequent morphology evolution support a dipole field driven formation mechanism. This work offers an improved understanding of the formation of other spherulites, in particular, naturally occurring mineral calcium carbonate spherulites.

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Section: Resultssupporting

confidence: 85%

Section: Resultsmentioning

confidence: 99%

Section: ■ Experimental Sectionmentioning

confidence: 99%

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Formation Mechanisms of ZnO Spherulites and Derivatives

Connolly

Greer

Zhou

2018

Crystal Growth & Design

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“…ZnO crystals have a typical dipolar structure with a charge separation on the two {0001} surface terminations, i.e., c(+) plane and c(-)plane. The formation of nanocones instead of nanorods or hexagonal bifrustum [34] implies that crystal growth only took place on one of the {0001} faces and the growth on the other face, the exposed face on the sphere surface, was suppressed. We assume the exposed faces of nanodiscs on the spherical particles are protected by EG or HMT molecules, these faces more likely terminated with the c(+)plane.…”

Section: Supporting Information)mentioning

confidence: 99%

Nanocone Decorated ZnO Microspheres Exposing the (0001) Plane and Enhanced Photocatalytic Properties

Greer

Zhou

Zhang

et al. 2017

Adv Materials Inter

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ZnO spherical particles exposing only the (0001) planes are prepared by an established solvothermal method using a water–ethylene glycol (EG) mix as a solvent. It is found that poorly crystalline nanoparticles form first, followed by their aggregation into microspheres consisting of crystallites embedded in EG and precursor molecules/ions. The grown up nanocrystallites and nanocones in the microspheres are all radially aligned. The possible formation mechanisms, in particular, the roles of water molecules, EG, and the intrinsic dipolar field of ZnO crystals, are discussed. X‐ray photoelecton spectroscopy experiments indicate that the spherical particles are terminated solely by zinc atoms. Brunauer–Emmett–Teller measurements in conjunction with the degradation of methylene blue dye data demonstrate that the photocatalytic performance of the ZnO spheres depends on the growth time and is significantly improved compared to traditional ZnO nanorods. This study is a rare example which combines nanostructural characterization of ZnO particles terminated with a single (0001) plane of known Zn2+‐polarity with their photocatalytic performance.

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“…[12][13][14][15] Moreover, previous research has established that surfaces with high energy usually have better properties in photocatalytic reaction. 16 So high-index facets would have good performance on photocatalytic applications.…”

Section: 5-9mentioning

confidence: 99%

Adjusting the proportions of {0001} facets and high-index facets of ZnO hexagonal prisms and their photocatalytic activity

Liu

Zhang

et al. 2017

RSC Adv.

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Zinc oxide (ZnO) hexagonal prisms with unique nanostructures are successfully synthesized via a simple hydrothermal method with the assistance of polyethylene glycol (PEG). Further studies demonstrated that dissolved PEG played a critical role in adjusting the exposed proportion of {0001} facets and high-index facets. By increasing the amount of PEG, we successfully reduced the exposed proportion of {0001} facets and increased the exposed proportion of high-index facets. The morphology and the properties of ZnO hexagonal prisms were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), Brunauer-Emmett-Teller N 2 gas adsorption-desorption isotherms, and photoluminescence (PL) spectra.The photocatalytic activity of the ZnO hexagonal prisms was investigated by photocatalytic degradation of methylene blue (MB) aqueous solution under UV-vis light irradiation. Results showed that the ZnO hexagonal prism samples with a high percentage of exposed high-index facets exhibited superior photocatalytic activity. The idea that adjusting the proportion of different facets to enhance the photocatalytic activity of ZnO samples is a meaningful study.

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Facile synthesis of novel hierarchical hollow ZnO microspheres

Abstract: Novel hierarchical hollow ZnO microspheres, composed of large ZnO crystals on the outer surfaces and small ZnO crystals on the inner surfaces, were synthesized by a chemically induced selftransformation process, employing the ester elimination between zinc formate dihydrate and ethanol.

Cited by 6 publications

References 18 publications

Formation Mechanisms of ZnO Spherulites and Derivatives

Formation Mechanisms of ZnO Spherulites and Derivatives

Nanocone Decorated ZnO Microspheres Exposing the (0001) Plane and Enhanced Photocatalytic Properties

Adjusting the proportions of {0001} facets and high-index facets of ZnO hexagonal prisms and their photocatalytic activity

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