Violet Emission in ZnO Nanorods Treated with High-Energy Hydrogen Plasma

Chen, Cong; Lu, Yangfan; He, Haiping; Xiao, Mu; Wang, Zheng; Chen, Lingxiang; Ye, Zhizhen

doi:10.1021/am403133u

Cited by 23 publications

(18 citation statements)

References 31 publications

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“…These PL emission bands originated from recombination of photoinduced charge carriers, zinc interstitial defects and oxygen vacancies in pure ZnO, as previously reported [1,26]. The violet emission band at 440 nm could be attributed to the zinc interstitial defects, while blue emission band at λ=490 nm and the green emission band at λ=510 nm could be attributed to surface states and oxygen vacancies in the ZnO NR [1,51]. Interestingly, the emission intensity of ZGQD1, ZGQD2 and ZGQD3 heterojunctions decreases as compared to bare ZnO, which indicate the decreased recombination of photoinduced electron-hole pairs, which is highly beneficial for photocatalytic activity.…”

Section: Photoluminescence Studiessupporting

confidence: 78%

ZnO-graphene quantum dots heterojunctions for natural sunlight-driven photocatalytic environmental remediation

Kumar

Dhiman

Sudhagar

et al. 2018

Applied Surface Science

139

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In this work, we report the formation of heterojunctions comprising of graphene quantum dots (GQD) decorated ZnO nanorods (NR) and its use as efficient photocatalysts for environmental remediation. The heterojunctions has been designed to be active both in the UV and visible light regions and anticipated utilize the maximum part of the solar light spectrum. In this view, we examined the photocatalytic performance of our heterojunctions towards the degradation of colored pollutant (methylene blue (MB) dye) and a colorless pollutant (carbendazim (CZ) fungicide) under sunlight irradiation. Compared to bare photocatalyst ZnO and GQD, the heterojunction with 2 wt% of GQD (ZGQD2) showed the best photocatalytic activity by effectively degrading (about 95%) of organic pollutants (MB and CZ) from water within a short span of 70 min. The superior photocatalytic activity of these ZnO-GQD heterojunctions could be attributed to efficient charge carrier separation lead suppressed recombination rate at photocatalyst interfaces. In addition to the enhanced light absorption from UV to visible region, the high specific surface area of ZGQD2 heterojunction (353.447 m² g-1) also imparts strong adsorption capacity for pollutants over catalyst surface, resulting in high photoactivity. Based on the obtained results, band gap alignment at ZnO-GQD heterojunction and active species trapping experiments, a plausible mechanism is proposed for photocatalytic reaction. The excellent photostability and recyclability of the ZnO-GQD heterojunctions fostering as promising photocatalyst candidate for environmental remediation applications.

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Section: Photoluminescence Studiessupporting

confidence: 78%

ZnO-graphene quantum dots heterojunctions for natural sunlight-driven photocatalytic environmental remediation

Kumar

Dhiman

Sudhagar

et al. 2018

Applied Surface Science

139

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“…Indeed, the low amount of oxygen vacancies in the ZnO film leads to an enhancement in the band gap emission [40,41]. Moreover it has been reported in literature that healing of oxygen vacancies by surface oxidation of ZnO surface promotes improvement in its optical properties [40][41][42]. This can explain the highest intensity of PL obtained in the case of ZnO film treated at 1.8 V, although this film has moderate surface area compared to the other films treated at 2.4 and 3.0 V.…”

Section: Accepted M Manuscriptmentioning

confidence: 99%

Nanostructuration and band gap emission enhancement of ZnO film via electrochemical anodization

et al. 2014

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A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT2 We report fabrication of nanostructured zinc oxide (ZnO) thin films with improved optical properties through electrochemical anodization. The ZnO films were produced over silicon substrates via radio-frequency (RF) plasma magnetron sputtering technique followed by electrochemical treatment in potassium sulfate solution. After electrochemical treatment, the effect of applied potential on the band gap emission behavior of ZnO films was investigated for the potential drop of 1.8, 2.4 and 3.0 V against reference electrode of Ag/AgCl/0.1M KCl. Depending on these values, ZnO films with different degrees of nonporous morphology, improved structural quality and oxygenrich surface chemistry were obtained. The treatment also resulted in enhancement of band gap emission from ZnO films with the degree of enhancement depending on the applied potential. As compared to the as-deposited films, a maximum increase in the photoemission intensity by more than 2.2 times was noticed. In this paper, any changes in the structure, surface chemistry and band gap emission intensity of the RF sputter deposited films, as induced by the anodization treatment at differential potential values, are discussed.

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“…[1][2][3][4][5] A variety of post-treatments, e.g. annealing, 6,7 plasma processing, 8,9 or coating with metal nanoparticles 10,11 or oxides, 12,13 have been explored with this aim in mind. The results and conclusions from different groups are frequently in disagreement, however, even in studies involving similar posttreatments.…”

Section: Introductionmentioning

confidence: 99%

Reagent concentration dependent variations in the stability and photoluminescence of silica-coated ZnO nanorods

Yin

Sun

Wang

et al. 2015

Inorg. Chem. Front.

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Silica (SiO 2 ) coating is finding increasing use as a means of improving the properties of ZnO nanomaterials. However, the current literature contains seemingly contradictory reports of the effect of such coatings on their photoluminescence (PL) properties. Two types of ZnO nanorod (henceforth termed Types A and B) were synthesized using the same hydrothermal method (differing only in the chosen precursor concentrations), then subjected to the exact same SiO 2 -coating procedure. SiO 2 coating is seen to have a strikingly different effect on the Type A and B nanorod morphologies and their PL. In the case of Type A nanorods, (i.e. nanorods grown using high precursor concentrations), SiO 2 coating has no discernible morphological effect but causes an obvious increase in the intensity of the visible component within the PL emission. Type B nanorods (grown from 20-times less concentrated reactive solution), in contrast, show a very different response to SiO 2 coating: morphologically, they appear as many ZnO nanodots in the silica shell that surrounds the etched ZnO core, and their ultraviolet PL is boosted. Systematic investigation of the effects of various other post-treatments on the PL from Type A and B nanorods leads to the conclusion that the different responses to SiO 2 coating can be traced to the different nanorod growth chemistries -i.e. by precipitation from Zn(OH) 2 intermediates (Type A nanorods) or by direct reaction of Zn 2+ and OH − ions (Type B material). The present study advances our understanding both of the controlled synthesis and of routes to optimising the properties of bare and silica-coated ZnO nanomaterials for nanodevice applications.

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Violet Emission in ZnO Nanorods Treated with High-Energy Hydrogen Plasma

Cited by 23 publications

References 31 publications

ZnO-graphene quantum dots heterojunctions for natural sunlight-driven photocatalytic environmental remediation

ZnO-graphene quantum dots heterojunctions for natural sunlight-driven photocatalytic environmental remediation

Nanostructuration and band gap emission enhancement of ZnO film via electrochemical anodization

Reagent concentration dependent variations in the stability and photoluminescence of silica-coated ZnO nanorods

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