Growth of Ultralong ZnO Nanowires on Silicon Substrates by Vapor Transport and Their Use as Recyclable Photocatalysts

Kuo, Tz-Jun; Lin, Chien‐Liang; Kuo, Chi-Liang; Huang, Michael H.

doi:10.1021/cm071568a

Cited by 276 publications

(184 citation statements)

References 22 publications

(17 reference statements)

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“…Semiconductor photo-catalysts offer huge potential for elimination of toxic chemicals [22]. ZnO, with bang gap = 3.37 eV, has become promising in the past few years because of its distinctive optoelectronic, catalytic, and photochemical properties [24,25]. It crystallizes in a hexagonal wurtzite structure (zincite).…”

Section: Introductionmentioning

confidence: 99%

Multiple-layered structure of obelisk-shaped crystalline nano-ZnO prepared by sol–gel route

2015

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Zinc oxide nanopowders were synthesized by the simple sol-gel method from an ethanol solution of zinc nitrate hexahydrate. Structural and surface morphological investigations were carried out using X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), scanning electron microscopy, Fourier transform infrared spectroscopy (FTIR) and ultraviolet-visible (UV-Vis) spectrophotometry analyses. XRD pattern showed that the zinc oxide nanoparticles exhibited hexagonal wurtzite structure. A multiple-layered structure of obelisk-shaped ZnO nanoparticles was achieved after calcinations. The average particle size of ZnO was around 20 nm as estimated by direct HRTEM observation. The size of sphere-like shaped ZnO nanoparticles was measured in the range of 20-80 nm and the size of pyramid-like shaped annealed samples was achieved in the range of 40-100 nm with less agglomeration. The energy dispersive spectroscopy spectrum showed peaks of zinc and oxygen. The sharp peaks in FTIR spectrum determined the Zn-O stretching and absorbance peak of UV-Vis spectrum showed the wide bandgap energy of 3.35 eV.

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Section: Introductionmentioning

confidence: 99%

Multiple-layered structure of obelisk-shaped crystalline nano-ZnO prepared by sol–gel route

2015

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“…16,17 The dense and uniform NWs have the length of ∼50 µm, diameter of ∼200 nm, and growth direction along the c-axis…”

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confidence: 99%

Flexible High-Output Nanogenerator Based on Lateral ZnO Nanowire Array

et al. 2010

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We report here a simple and effective approach, named scalable sweeping-printing-method, for fabricating flexible highoutput nanogenerator (HONG) that can effectively harvesting mechanical energy for driving a small commercial electronic component. The technique consists of two main steps. In the first step, the vertically aligned ZnO nanowires (NWs) are transferred to a receiving substrate to form horizontally aligned arrays. Then, parallel stripe type of electrodes are deposited to connect all of the NWs together. Using a single layer of HONG structure, an open-circuit voltage of up to 2.03 V and a peak output power density of ∼11 mW/cm 3 have been achieved. The generated electric energy was effectively stored by utilizing capacitors, and it was successfully used to light up a commercial light-emitting diode (LED), which is a landmark progress toward building self-powered devices by harvesting energy from the environment. This research opens up the path for practical applications of nanowire-based piezoelectric nanogeneragtors for self-powered nanosystems.KEYWORDS Nanogenerator, ZnO, nanowire, light-emitting diode, self-powering E nergy harvesting is critical to achieve independent and sustainable operations of nanodevices, aiming at building self-powered nanosystems. 1-3 Taking the forms of irregular air flow/vibration, ultrasonic waves, body movement, and hydraulic pressure, mechanical energy is ubiquitously available in our living environment. It covers a wide range of magnitude and frequency from cell contraction to ocean waves. The mechanical-electric energy conversion has been demonstrated using piezoelectric cantilever working at its resonating mode. [4][5][6][7] However, the applicability and adaptability of the traditional cantilever based energy harvester is greatly impeded by the large unit size, large triggering force and specific high resonance frequency. Recently, a series of rationally designed nanogenerators (NGs) with piezoelectric nanowires (NWs) have shown great potentialtoscavengetinyandirregularmechanicalenergy. [8][9][10][11][12][13][14][15] However, insufficient electric output hinders their practical applications. We report here a simple and effective approach, named scalable sweeping-printing-method, for fabricating flexible high-output nanogenerator (HONG). An open-circuit voltage of up to 2.03 V and a peak output power density of ∼11 mW/cm 3 have been achieved. The generated electric energy was effectively stored by utilizing capacitors, and it was successfully used to light up a commercial lightemitting diode (LED), which is a landmark progress toward building self-powered devices by harvesting energy from the environment. Furthermore, by optimizing the density of the NWs on the substrate and with the use of multilayer integration, a peak output power density of ∼0.44 mW/cm 2 and volume density of 1.1 W/cm 3 are predicted.The mechanism of converting mechanical energy by a single ZnO NW that is laterally bonded to a substrate has been discussed in details in our previous rep...

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“…20 To achieve nitrogen doping in ZnO nanowires as well as to passivate defect states, NH 3 plasma irradiation was subsequently carried out using plasma-enhanced chemical vapor deposition at high frequency (40.68 MHz). The plasma power density was 1.2 W/cm 2 and the deposition was carried out at 350 C. To activate nitrogen dopants and control dopant concentration, samples were post-annealed in a N 2 atmosphere at different temperatures.…”

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confidence: 99%

Nitrogen deep accepters in ZnO nanowires induced by ammonia plasma

Huang

Guo

et al. 2011

Applied Physics Letters

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Nitrogen doping in ZnO nanowires was achieved through ammonia plasma treatment followed by thermal annealing. The strong dependence of the red light emission from the nanowires excited by 2.4 eV on the nitrogen concentration, suggests that the red light emission originates from nitrogen related defects. The mechanism responsible for the red light emission is in good agreement with the deep-acceptor model of nitrogen defects, clarifying that nitrogen atoms caused deep accepters in ZnO nanowires. Based on this model, the enhanced green emission from defects in nitrogen-doped samples (excited by 325 nm line) can be well explained by the increase of the concentration of activated oxygen vacancies resulting from the compensation of nitrogen deep acceptors.

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Growth of Ultralong ZnO Nanowires on Silicon Substrates by Vapor Transport and Their Use as Recyclable Photocatalysts

Cited by 276 publications

References 22 publications

Multiple-layered structure of obelisk-shaped crystalline nano-ZnO prepared by sol–gel route

Multiple-layered structure of obelisk-shaped crystalline nano-ZnO prepared by sol–gel route

Flexible High-Output Nanogenerator Based on Lateral ZnO Nanowire Array

Nitrogen deep accepters in ZnO nanowires induced by ammonia plasma

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