ZnO nanostructures grown on vertically aligned carbon nanotubes by laser-assisted flow deposition

Rodrigues, Joana; Mata, D.; Fernandes, A.J.S.; Neto, M.A.; Silva, Rui; Monteiro, T.; Costa, F.M.

doi:10.1016/j.actamat.2012.06.005

Cited by 25 publications

(38 citation statements)

References 38 publications

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“…In fact, the high density of the CNTs array hinders the ZnO particles penetration into the CNTs forest causing the surface particles distribution. As for the case of the as-grown samples the low temperature PL measurements performed in the ZnO/CNTs composites showed that the emission was dominated by the near band edge recombination although the green band was also observed 33 . Additionally, when a comparison is made with the samples deposited in silicon substrate an enhancement of the overall luminescence intensity was observed for the composites 33 .…”

Section: Zno/cnts Compositesmentioning

confidence: 99%

“…In order to preserve the alignment a complete cover of the CNTs with ZnO particles is needed, which has not yet been accomplished. A detailed characterization of the first type of samples can be found in a previously reported article 33 . Figure 11 shows SEM micrographs of one of those samples.…”

Section: Zno/cnts Compositesmentioning

confidence: 99%

“…The beam is focused on the tip of the extruded cylindrical rods, previously prepared by mixing the ZnO powders (AnalaR, 99.7%) with polyvinyl alcohol (PVA, 0.1 g.ml -1 , Merck). The substrates are placed on a sample holder attached to the upper spindle of the LFZ system, above the feed rod as previously described 33 .…”

Section: Lafd Growth Of Znomentioning

confidence: 99%

“…Previous studies showed that laser assisted flow deposition (LAFD) offers some advantages in the deposition of ZnO nanostructures onto vertically aligned carbon nanotubes (VACNTs) arrays since it allows the synthesis of ZnO in a single step directly on top of the VACNTs preserving their structure and alignment 33 .…”

Section: Introductionmentioning

confidence: 99%

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ZnO micro/nanocrystals grown by laser assisted flow deposition

et al. 2014

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Laser assisted flow deposition (LAFD) is a very high yield method based on a vapor-solid mechanism, allowing the production of ZnO crystals in a very short time. The LAFD was used in the growth of different morphologies (nanoparticles, tetrapods and microrods) of ZnO micro/nanocrystals and their microstructural characterization confirms the excellent crystallinity of the wurtzite structure. The optical properties of the as-grown ZnO crystals investigated by low temperature photoluminescence (PL) evidence a well-structured near band edge emission (NBE) due to the recombination of free (FX), surface (SX) and donor bound (D 0 X) excitons. Among the most representative emission lines, the 3.31 eV transition was found to occur in the stacking faults-free microrods. The luminescence behavior observed in H passivated samples suggests a closer relationship between this optical center and the presence of surface states.Besides the unintentionally doped micro/nanocrystals, ZnO/Ag and ZnO/carbon nanotubes (CNT) hybrid structures were processed by LAFD. The former aims at the incorporation of silver as a p-type dopant and the latter envisaging photovoltaic applications. Silver-related spherical particles were found to be inhomogeneously distributed at the microrods surface, accumulating at the rods tips and promoting the ZnO nanorods re-nucleation. Despite the fact that energy dispersive X-ray measurements suggest that a fraction of the silver could be incorporated in the ZnO rods, no new related luminescence lines or bands were observed when compared with the as-grown samples. For the case of the ZnO/CNT composites two main approaches were adopted: i) a direct deposition of ZnO particles on the surface of vertically aligned multi-walled carbon nanotubes (VACNTs) forests without employing any additional catalyst and ii) new ZnO/CNT hybrids were developed as buckypaper nanocomposites. The use of the LAFD technique in the first approach preserves the CNTs structure and alignment and avoids the collapse of the VACNTs array, which is a major advantage of this method. On the other hand, LAFD grown ZnO nanoparticles and tetrapods were used to produce ZnO/CNT buckypaper nanocomposites. When compared with the as-grown samples the PL spectra of the composites structures behave differently. For the case of the ZnO/VACNTs no changes on the peak position and spectral shape were observed. Only an enhancement of the overall luminescence was found to occur. On contrary, for the buckypaper nanocomposites notable changes on the spectral shape and peak position were observed, likely due to distinct surface band bending effects for the ZnO nanoparticles and tetrapods embedded in the CNTs.

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Section: Zno/cnts Compositesmentioning

confidence: 99%

Section: Zno/cnts Compositesmentioning

confidence: 99%

Section: Lafd Growth Of Znomentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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ZnO micro/nanocrystals grown by laser assisted flow deposition

et al. 2014

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“…Nas décadas passadas, a indústria química abriu novos mercados para este material, como na produção de catalisadores, cerâmicas avançadas, pigmentos, absorvedor de energia, material antibiótico, entre outros. 52,53,54 A seguir, apresentamos brevemente aplicações recentes de ZnO envolvendo interação com a radiação solar, as quais tem sido aplicações de alto interesse tecnológico nos últimos anos.…”

Section: Algumas Aplicações De Zno Nanoestruturadounclassified

Synthesis, Properties and Applications of Nanostructured Zinc Oxide

Mayrinck¹,

Raphael²,

Ferrari³

et al. 2014

Revista Virtual De Química

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Nanostructured materials are undergoing rapid development due to their potential applications in a wide variety of technological areas such as electronics, catalysis, ceramics, photodetectors, sensors, solar cells, among others. However, it is fundamental the studies of the properties, synthesis conditions and applications of nanostructured materials. A material that has been highlighted due to its mechanical, electrical, magnetic, optical and chemical properties is the zinc oxide (ZnO). In zinc oxide such properties mainly depend on the size and morphology of the material. Therefore, the present paper aims to conduct a literature review on the main synthesis methods to obtain different ZnO nanostructures.Keywords: Zinc oxide; nanostructures; synthesis. ResumoMateriais nanoestruturados vêm passando por um rápido desenvolvimento devido as suas potenciais aplicações em uma ampla variedade de áreas tecnológicas, tais como eletrônica, catálise, cerâmica, fotodetectores, sensores, células solares, entre outras. Porém, torna-se fundamental o estudo das propriedades, condições de síntese e aplicações de materiais nanoestruturados. Um material que vem se destacando devido as suas propriedades mecânicas, elétricas, magnéticas, ópticas e químicas é o óxido de zinco (ZnO). No óxido de zinco tais propriedades dependem principalmente do tamanho e morfologia de suas partículas. Sendo assim, o presente artigo tem o intuito de realizar uma revisão bibliográfica acerca dos principais métodos de síntese para obtenção de diferentes nanoestruturas de ZnO.Palavras-chave: Óxido de zinco; nanoestruturas; síntese.

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Photocatalytic Activity of Laser‐Processed ZnO Micro/Nanocrystals

Rodrigues

Pimentel

Fortunato

et al. 2018

Physica Status Solidi (a)

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With a bandgap energy of ≈3.3 eV at room temperature, zinc oxide (ZnO) exhibits physical properties that make it a potential candidate for several technological applications. Sustainable development requires, among other actions, removal of organic pollutants by employing non‐toxic structures, which can be achieved considering the photocatalytic properties of ZnO. In this work, high optical and structural quality ZnO crystals with distinct morphologies (nanotetrapods and microrods) are produced by laser‐processing. By adding silver to the growth precursors it is possible to produce ZnO/Ag composites in a single and short step, boosting a synergetic conjugation of the properties of both materials. The ZnO structures produced with and without silver are fully characterized by electronic microscopy and optical spectroscopy. Moreover, their photocatalytic activity is analyzed using methylene blue as a model‐test contaminant, revealing that the nanotetrapods exhibit a better performance than the microrods. This effect is further enhanced by the presence of silver on the ZnO surface, hindering the photoinduced carriers’ recombination, as corroborated by the photoluminescence results.

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ZnO nanostructures grown on vertically aligned carbon nanotubes by laser-assisted flow deposition

Cited by 25 publications

References 38 publications

ZnO micro/nanocrystals grown by laser assisted flow deposition

ZnO micro/nanocrystals grown by laser assisted flow deposition

Synthesis, Properties and Applications of Nanostructured Zinc Oxide

Photocatalytic Activity of Laser‐Processed ZnO Micro/Nanocrystals

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