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The relaxed atomic structures of S-doped ZnO in the simulation supercell in (a) substitutional (SO) and (b) interstitial (SI) geometries. Red (grey) balls indicate O (Zn) atoms, while the yellow balls represent S atoms. Visible local bond distortions accompany S inclusion in the ZnO matrix, because of its larger atomic radius with respect to O. Two different orientations (along-a-and perpendicular-b-the polar axis) are represented to highlight different features; unitary cell in panel b is replicated for clarity.
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The synthesis of ZnO porous nanobelts with high surface-to-volume ratio is envisaged to enhance the zinc oxide sensing and photocatalytic properties. Yet, controlled stoichiometry, doping and compensation of as-grown n-type behavior remain open problems for this compound. Here, we demonstrate the effect of residual sulfur atoms on the optical prope...
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... can interpret the aforeshown experimental results on the basis of the theoretical predictions of Density Functional Theory. To get a one-to-one understanding of the effect of sulfur, we adopted a simplified model, representative of the experimental system (see Fig. 5): bulk calculations of S inclusion in substitutional O sites have been performed at similar amounts of sulfur as evaluated by EDX studies (~0.8-1.6%). The overall exper- imental sample dimensions, that present ZnO contiguous portions of several hundreds of nm 3 , can be properly reproduced by a bulk simulation; the presence of a ...
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... that present ZnO contiguous portions of several hundreds of nm 3 , can be properly reproduced by a bulk simulation; the presence of a surface or interface does not induce remarkable effects: a discussion of the ZnO/ZnS interface is reported in Supplementary Information (SI) for completeness. At these defect contents, upon atomic relaxation (see Fig. 5a), we observe a small local rearrangement of atomic coordi- nates around the dopant site, induced by the large atomic radius of S compared to O. The bond distortion close to the defect site is accompanied by charge rearrangements that are responsible for an occupied extra filled peak mid-gap in the DOS, ~0.8 eV above the host valence ...
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... in the ZnO lattice (Fig. 4b): S I almost substitutes an oxygen atom (O I ), which is displaced in an interstitial site, confirming the attitude of S to assume O-substitutional configurations. The simultaneous interaction with nearest-neighbor Zn and O I atoms promotes a shift of the S-related extra-peak at higher energies in the band gap (Fig. 5, bottom panel). Both in the substitutional and interstitial configurations these are filled peaks at ~0.8-1 eV above the ZnO VBM: this effect is not consistent with the interpretation of a possible role in n-doping for S 13 ...
Citations
... In the literature, there some studies on sulfur -doped ZnO nanostructures with different sizes and shapes, such as the nanorods [15,16], nanospires [17], nanowires [18][19][20][21], nanonails [22] mesoporous nanobelts [23], nanostars [24] nanosphere [25], microspheres [26] and nanoparticles [27][28][29]. All these studies mentioned above have been achieved to enhance the optoelectronic features of ZnO nanostructures and then used for various kinds of applications, including the environmental pollution, transparent flexible nanogenerator, antibacterial activity, solar cells and photocatalyst, etc. ...
... Due to the large electron negativity and the anionic radius difference between S (r 2-= 0.18 nm) and O(r 2-= 0.14 nm), sulfur doping can modify the structure, optical and electrical properties of ZnO thin films and hence ZnO:S can be attracted as alternative window or electron transport layer in photovoltaic devices. Even though S doping in ZnO lattice can modify the optical properties by its negative (S − 1 /S 2-)states, the coexistence positive of charge states (S + /S 2+ ) may leads to the p-type conductivity and it can cause charge compensation [41]. Hence, simultaneous band gap modification and charge compensation are possible by sulfur doping in ZnO. ...
... The incorporation of the S into the ZnO narrows the optical band gap to 2.8 eV as seen inset Fig. 7d). The modification of optical band gap can be attributed to the induced intraband states responsible by the S doping [41]. The sharp absorption edge can be identified around 400 nm corresponding to a direct electron transition from the valence band to the conduction band [7]. ...
In this study, we deposit sulfur incorporated ZnO thin films (ZnO:S) by ultrasonic deposition and analyze changes in the structure, morphology, optical and electrical properties of the films in comparison with the pristine ZnO thin films. Further, electronic band structures of ZnO and (ZnO:S) were theoretically calculated using DFT-VASP method. ZnO and (ZnO:S) thin films formed at different conditions showed hexagonal crystal structure with crystallites of 30–40 nm in size fully oriented along [002] direction perpendicular to substrate. The optical band gap of ZnO was 3.2 eV which was reduced to 2.8 eV due to sulfur incorporation. Vacuum annealed ZnO showed a very low sheet resistance of 67 Ω/□ and the value was increased to 470 Ω/□ in ZnO:S films, nearly metallic behavior. Hall effect measurements confirmed the n-type conductivity with a maximum carrier concentration of 5.6 × 1020 cm−3. These films can find potential applications as window layers with improved charge extraction contacts for solar cell applications.
... Finally, the mixture (S/ ZnO) was filtered, washed with double distilled water until the pH of the removed water reaches 7 to check the purity of the product, air-dried overnight, and heat-dried at 300°C for 1 h. 26,27 ZnO−ZnS heterostructures were obtained using the sol−gel synthesis method after ZnO-NPs were doped with ZnS. The procedures were summarized pictorially as indicated in Figure 1. ...
Metal oxide nanoparticles (MO-NPs) are presently an area of intense scientific research, attributable to their wide variety of potential applications in biomedical, optical, and electronic fields. MO-NPs such as zinc oxide nanoparticles (ZnO-NPs) and others have a very high surface-area-to-volume ratio and are excellent catalysts. MO-NPs could also cause unexpected effects in living cells because their sizes are similar to important biological molecules, or parts of them, or because they could pass through barriers that block the passage of larger particles. However, undoped MO-NPs like ZnO-NPs are chemically pure, have a higher optical bandgap energy, exhibit electron-hole recombination, lack visible light absorption, and have poor antibacterial activities. To overcome these drawbacks and further outspread the use of ZnO-NPs in nanomedicine, doping seems to represent a promising solution. In this paper, the effects of temperature and sulfur doping concentration on the bandgap energy of ZnO nanoparticles are investigated. Characterizations of the synthesized ZnO-NPs using zinc acetate dihydrate as a precursor by a sol-gel method were done by using X-ray diffraction, ultraviolet-visible spectroscopy, and Fourier transform infrared spectroscopy. A comparative study was carried out to investigate the antibacterial activity of ZnO nanoparticles prepared at different temperatures and different concentrations of sulfur-doped ZnO nanoparticles against Staphylococcus aureus bacteria. Experimental results showed that the bandgap energy decreased from 3.34 to 3.27 eV and from 3.06 to 2.98 eV with increasing temperature and doping concentration. The antibacterial activity of doped ZnO nanoparticles was also tested and was found to be much better than that of bare ZnO nanoparticles.
... In order to modify the optical and electrical properties of 1D ZnO nanomaterials, doping elements, such as In, Mn and Ga, into those ZnO nanostructures has become an important subject in recent years [21][22][23]. Due to the size differences as well as electrostatic (Coulomb) repulsion between S and O, S-doped ZnO materials are expected to modify the electrical and optical properties of ZnO [24,25]. ...
The photochemical properties of nanomaterials have always been a research focus in the preparation and optoelectronic applications of nanomaterials. In this work, the porous S-doped ZnO nanowires with cigarette shape were firstly fabricated by direct reaction of zinc foil in aqueous solution of sodium hyposulfite at constant temperature (65 °C). It can be determined that the as-synthesized nanomaterial is elemental S-doped ZnO nanowire with a half-arc mesoporous superstructure characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersion spectroscopy (EDX). Further, through the characterization of photochemical properties, an enhanced photochemical property was observed, indicating the S-doped ZnO nanowire with half-arc mesoporous superstructur have potential applications in dye sensitized photoelectrochemical cells, gas sensors, biosensors, optoelectronic devices, and so on.
... Wide band gap semiconductors, such as TiO 2 , SnO 2 , In 2 O 3 , and ZnO, have attracted many researchers due to their potential applications for future electronic, optic, and optoelectronic devices [5]. Among the wide band gap materials, the ZnO structure is more attractive due to the controllable electrical [6] and optical properties [7,8]. Based on these properties, ZnO has wide applications for use in transparent thin film transistors [9], transparent electrodes [10], light emitting diodes [11], gas sensors [12], and especially for UV photodetectors [13]. ...
We study the influence of Ti doping on the photodetection properties of zinc oxide (ZnO) thin films. The pure ZnO and ZnO:3%Ti (TZO) films were deposited on Si substrates by using DC-unbalanced magnetron sputtering. From the scanning electron microscopy (SEM) images, the TZO film grows more homogeneously in comparison with the pure ZnO structure. We suggest that Ti dopants play a role in uniformly distributing ZnO elements from the sputtering target to the Si substrate. The transmittance spectra of the Fourier transform infrared spectroscopy show a peak splitting of Zn-O stretching in the TZO film, which is also related to the dopant-modified film morphology. X-ray diffraction (XRD) spectra show that the Ti dopants also change the main ZnO crystal orientation from (0 0 2) to (1 0 3). The ZnO and TZO film-based photodetectors were fabricated by using a metal-semiconductor-metal planar configuration with Ag as the metal contact. Based on the I-V characteristics, Ti doping in the ZnO system reduces the dark current and induces the enhancement of the photo-to-dark-current ratio. Our study shows the important role of Ti doping on the improvement of photodetection performance.
Incorporating non-metal elements through doping proves to be a highly effective strategy for expanding the photoresponse range of ZnO. This study prepared pristine ZnO and 1%S-doped ZnO through an environmentally friendly approach, employing the biosynthesis method using bidara leaf extract. The synthesized samples were characterized using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and UV-Vis spectroscopy to investigate the structure, morphology, and the optical properties of ZnO, respectively. The XRD analysis revealed a noticeable shift in the diffraction pattern towards smaller angles, indicating the successful incorporation of sulfur into the ZnO lattice. Additionally, FESEM images displayed a distinct modification in the morphology of the ZnO particles upon sulfur doping, accompanied by a reduction in particle size. UV-Vis spectroscopy confirmed that both ZnO and sulfur-doped ZnO exhibited optical absorption predominantly in the ultraviolet (UV) region. Notably, the presence of sulfur doping led to an increase in the optical absorption of ZnO, while simultaneously narrowing its energy bandgap. These findings highlight the potential of sulfur doping as an effective means to enhance the structural, morphological, and optical properties of ZnO semiconductor materials, thereby opening up possibilities for various optoelectronic applications.
The influence of S doping on the structural, electronic, and photocatalytic properties of the ZnO surface has been investigated by using the GGA+U method. We found that the doping with S atoms is energetically favored. The calculated DOS curves show that the S doping leads to the appearance of new electronic levels in the forbidden band. Consequently, the electronic structures and properties of the ZnO (101¯0) surface may be greatly affected. Furthermore, we found that the work function of the ZnO (101¯0) surface was decreased after doping with sulfur. This decrease in work function is accompanied by an increase in the band gap. The suitability of the S-doped ZnO (101¯0) surface for photocatalytic applications was also discussed and compared to the case of the O-deficient surface. We found that the formation of the SO-VO defect may enhance the photocatalytic properties of the ZnO (101¯0) surface.
The 1D nanomaterials, which may exist as wires, fibers, belts, tubes or rods, arouse wide attention because they are significant in fundamental scientific research and may potentially be applied in the field of nanotechnology (Li and Xia in Nano Lett 4:933–938, 2004; Tian et al. in Nature 449:885–889, 2007; Zheng et al. in Science 333:206–209, 2011).
Many green synthesis methods are used for synthesizing the nanoparticles in order not to harm humankind which makes use of it. Sunscreen is one of the vital products that play a vital role in human life nowadays. Sunscreens are generally prepared with titanium dioxide and zinc oxide nanoparticles due to their higher bandgap which helps to protect the skin from UVB and UVA rays respectively. These nanoparticles are chemically prepared as far as now in the case of sunscreen products. Titanium dioxide nanoparticle does not give full protection over the UV-A spectrum when compared to Zinc oxide nanoparticle. So, sunscreen manufacturers opt for ZnO nanoparticles to give better results. Our motivation is to prepare green synthesized ZnO nanoparticles to use in the preparation of transparent sunscreen. Here we use Aloe barbadensis leaf extract for the synthesis of ZnO nanoparticles.
Engineering of highly efficient and cost-effective photoanodes are urgently required for the clean fuel generation. Herein, a CdSe(en)0.5 (en = ethylenediamine) hybrid photoanodes were synthesized by a solvothermal approach. It was revealed that the second in-situ hydrothermal successfully converts the cadmium foil-based inorganic–organic CdSe(en)0.5 hybrid nanosheets to oriented cadmium hydroxide crowned CdSe nanowire-decorated porous nanosheet (Cd(OH)2/CdSe NW/NS) heterostructure by dissolution and regrowth mechanism. The alteration in second hydrothermal reaction conditions could modify the morphology and optical properties of the Cd(OH)2/CdSe NW/NS) heterostructure photoanodes. The possible growth mechanism of Cd(OH)2/CdSe NW/NS porous structure is studied at various second hydrothermal times using the control experiments of the synthesis. The optimized 3D porous Cd(OH)2/CdSe NW/NS photoanodes exhibited outstanding photocurrent density of 6.1 mA.cm⁻² at 0 V vs Ag/AgCl, which is approximately 7.6 times higher than that of inorganic–organic CdSe(en)0.5 hybrid under light irradiation (>420 nm cut off filter). A mechanism is proposed to explain the enhanced charge separation at the Cd(OH)2/CdSe NW/NS photoanode/electrolyte interface. which is supported by PL and photoelectrochemical analyses. These findings open an avenue of phase and morphology transmutation for efficient formation of other hierarchical structures of metal selenides and sulfides. Additionally, the Al2O3 co-catalyst can act as effective hole trapping sites and improves the stability of the photoelectrode through the timely consumption of the photogenerated charges, particularly the holes.
