S-doped ZnO Research Articles

S-doped ZnO photoelectrode modified with silver and platinum nanoparticles and their photocatalytic activity for progesterone degradation

Zinc oxide doped with sulfur (ZnO-S) has presented improved photocatalytic activity under visible irradiation. In this work, ZnO-S film was efficiently prepared by thermal decomposition from zinc sulfide (ZnS) in an oxidizing atmosphere. X-ray diffraction analysis (XRD) showed ZnS phase transformation occurred from cubic sphalerite to ZnO hexagonal wurtzite at temperatures between 500 and 600 °C. ZnO-S electrodes prepared onto a transparent conductive substrate were modified by silver (Ag0) or platinum (Pt0) nanoparticles (NPs). X-ray photoelectron spectroscopy (XPS) confirmed that sulfur was incorporated into ZnO structure. Field Emission Gun-Scanning Electron Microscope (FEG-SEM) images showed that occur a drastic modification in the particle morphology of the films treated at distinct temperatures. Photoelectrochemical investigation displayed a negative photopotential (∆E<0) for all photoelectrode investigated as well as superior photocurrents for samples modified with metallic Ag0 and Pt0 NPs. In order to investigate the photoelectroactivity, ZnO-S6, Ag0/ZnO-S6, Pt0/ZnO-S6 and commercial ZnO electrodes were used to degrade progesterone solution under polychromatic irradiation. The superior performances were observed for ZnO-S films functionalized with Ag0 or Pt0. Therefore, the results showed advances in the degradation of organic contaminants in the water treatment process and possible contributions to a better use of solar radiation.

Cost-effective efficient materials for dye degradation using non-aqueous sol-gel route.

In the present studies, the synthesis of pure ZnO nanoparticles and Mg and S-doped ZnO particles were carried out using a non-aqueous sol-gel method. The synthesized nanoparticles (NPs) are characterized using XRD, FESEM, EDX, FTIR, UV-Vis-DRS, XPS, PL, and BET surface area analysis. X-ray diffraction (XRD) techniques were used to examine the crystallization of ZnO, Mg-ZnO, and S-ZnO samples. The Mg-ZnO and S-ZnO samples exhibit significant c-axis compression and smaller crystallite sizes as compared to undoped ZnO. The optical band gap of Mg-ZnO and S-ZnO NPs were found to be 2.93eV and 2.32eV, respectively, which are lower than that of ZnO NPs (3.05eV). The S-doped ZnO resulted in the homogenous distribution of sulfur ions in the ZnO lattice crystal. XPS analysis revealed that the doped S element was mostly S4+ and S6+. A systematic evaluation has been conducted to assess the influence of several operational parameters, including doped/undoped stoichiometry, solution pH, catalyst dosage, and radical trapping experiment, on the photocatalytic degradation of Rhodamine 6G (Rh 6G) dye. Furthermore, we investigated the photocatalytic degradation activity of ZnO, Mg-ZnO, and S-ZnO samples with aquoues solution of 5ppm Rhodamine 6G (Rh 6G) at room temperature. Results indicated that pure ZnO nanoparticles have the highest photocatalytic degradation rate constant (0.00344min-1), compared to the samples Mg-ZnO (0.00104min-1) and S-ZnO (0.00108min-1) with Rh 6G dye in presence of visible light emitting diode (Vis-LED) source at room temperature. The enhanced visible light photocatalytic activities of pure ZnO NPs were attributed to their superior surface properties (18.30 m2/g) and effective electron-hole separation.

Physical properties of different polymorphs of sulfur doped ZnO studied in the framework of first-principles approaches

Various physical properties of pure and sulfur-doped zinc oxide in the germanium phosphide (GeP), cesium chloride (CsCl), and nickel arsenide (NiAs) type structures are studied using the first-principles approaches in this research. The structural characteristics of the ZnOS alloys in GeP, CsCl, and NiAs type polymorphs show a slight deviation from Vegard's law, which is consistent with the available literature. It is observed that the electronic band structures of the ZnOS alloys show an exciting impact of sulfur (S) substitution in the ZnO. The ZnOS alloys, in CsCl type structure, display their metallic character. The static dielectric constants of the GeP, CsCl, and NiAs type’s polymorphs demonstrate that with increasing S concentration, polarization is enhanced. Moreover, the CsCl type phase of the ZnOS alloys exhibits the maximum value of the static dielectric constant along with showing metallic character. The optical results highlight the potential of S-doped ZnO in these structures as the highest absorption, reflectivity, and conductivity peaks shift towards low photon energies. The examination of the absorption spectra demonstrates that GeP-type ZnOS alloys are suitable for infrared to visible regime applications. On the other hand, NiAs-type ZnOS alloys are appropriate for use in the visible light regime.

Biosynthesis of sulfur-doped zinc oxide using bidara leaf extract

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.

Visible light assisted degradation of Rhodamin B by reusable S-doped ZnO thin film photocatalyst

The use of zinc oxide-based photocatalysts has been extensively conducted to breakdown harmful pollutants in wastewater treatment. Recently, ZnO doped non-metal can improve photocatalytic activity by reducing charge carrier recombination. Here, S-doped ZnO thin films, with a sulfur dopant of 1 and 5% molar, were synthesized by a seed-mediated hydrothermal process. The enhancement in crystal structure and morphology were noted with the presence of sulfur in the ZnO system. The photocatalytic test shows that the presence of sulfur enhances Rhodamine B (RhB) degradation efficiency up to 92% with reaction rates of 1.67 × 10−2 min−1 under visible light. The S-doped ZnO thin film is potentially applied as a stable photocatalyst for wastewater purification, with a noted photocatalytic efficiency of 75% after repeated use.

Conductometric acetic anhydride gas sensors based on S-doped porous ZnO microspheres with enhanced Lewis base interaction

Acetic anhydride is an essential raw material for manufacturing the drug heroin. Its rapid detection using semiconductor sensors has great significance to curb the spread of drugs. However, there are few reports on the design of semiconductor sensors for acetic anhydride, and the sensing mechanism remains unclear. For this reason, the strategy enhancing the Lewis base sites on the ZnO surface via S-doped is proposed in view of the Lewis acid properties of acetic anhydride combined with Lewis acid base theory. The synthesized S-doped porous spherical ZnO (S-ZnO-600) sensor response (312.4) to 100 ppm acetic anhydride is 4.9 times than ZnO-600 (64.1) with a detection limit of 200 ppb. X-ray photoelectron spectroscopy (XPS), Electron paramagnetic resonance (EPR) and the electron localization function (ELF) indicate that S-doped greatly modulates the electronic structure of ZnO through lattice defects. Meanwhile, the increase of Lewis basicity on the ZnO surface through S doping is further confirmed using CO2 temperature programmed desorption (CO2-TPD), the frontier molecular orbital and the charge density difference (CDD). Gas-phase mass spectrometry (GP-MS) combined with DFT further reveals the catalytic degradation of acetic anhydride sensing process.

One-pot integration of S-doped BiOCl and ZnO into type-II photocatalysts: Simultaneously boosting bulk and surface charge separation for enhanced antibiotic removal

Ameliorating the charge separation behavior of photocatalysts is urgent and promising in current investigation of solar light-driven antibiotic removal. Herein, we introduce a facile hydrothermal approach for one-pot integration of sulfur-doped BiOCl (denoted as S-BiOCl) and ZnO into type-II photocatalysts (denoted as ZnO/S-BiOCl). The as-prepared ZnO/S-BiOCl exhibits an appealing removal rate for antibiotic (including tetracycline (TC) and tetracycline hydrochloride (TC-HCl)) in comparison with ZnO/BiOCl composites, individual S-BiOCl and ZnO. This satisfactory performance could be ascribed to the synergic effect of S dopant level in band gap of BiOCl and type-II heterojunctions between S-BiOCl and ZnO for simultaneously boosting charge separation in both bulk and surface. This work can afford an ingenious strategy in constructing high-performance BiOCl-based photocatalysts coupled heterojunction engineering with element doping engineering for antibiotic removal.

Effect of doping with sulfur atoms on the electronic and photocatalytic properties of the ZnO(10[formula omitted]0) surface: A DFT+U study

The influence of S doping on the structural, electronic, and photocatalytic properties of the ZnO(101¯0) 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.

One-Pot Integration of S-Doped Biocl and Zno into Type-Ii Photocatalysts: Simultaneously Boosting Bulk and Surface Charge Separation for Enhanced Antibiotic Removal

One-Pot Integration of S-Doped Biocl and Zno into Type-Ii Photocatalysts: Simultaneously Boosting Bulk and Surface Charge Separation for Enhanced Antibiotic Removal

Enhanced photochemical properties of S-doped ZnO half-arc mesoporous superstructured nanowires

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.

Tuning the Electronic Structure and Optical Properties of S-Doped ZnO under Pressure

In this work, the geometrical, electronic structures and optical properties of S-doped ZnO at high pressures have been investigated. The pressure effects on the lattice parameters, the electronic band structures, and partial density of states (PDOS) of crystalline S-doped ZnO are calculated up to 10 GPa by performing density functional calculations. Within the studied pressure range, the lattice parameters have the strongest pressure dependence with $$\Delta c = 0.152\;\AA$$ , whereas a show a pressure dependence $$\Delta a = 0.075\;\AA$$ of up to 10 GPa. The non-uniform pressure dependence of the lattice parameters may imply that the sample undergoes anisotropic compression with pressure. The electronic structure of S-doped ZnO under high pressure is also discussed. Moreover, the evolution of the dielectric function, absorption coefficient ( $$\alpha ({\omega })$$ ), reflectivity ( $$R({\omega })$$ ), and the real part of the refractive index ( $$n({\omega })$$ ) at high pressure are also presented.

Chitosan modified N, S-doped TiO2 and N, S-doped ZnO for visible light photocatalytic degradation of tetracycline.

N, S-doped TiO2 (NST), N, S-doped ZnO (NSZ) and their composite with chitosan (NST/CS, NSZ/CS) were synthesized by sol gel-hydrothermal method. The prepared samples were characterized using XRD, FTIR, TEM and BET techniques. These photocatalysts were used for the photocatalytic degradation of tetracycline under visible light irradiation. At screening test, NST/CS had the highest tetracycline degradation efficiency of 91% for duration of 20 min under visible light. The blending of chitosan with NST increases the rate of photocatalytic degradation of tetracycline about 2 times. A detail characterization including HRTEM, SEM, EDS and DRS were conducted for NST/CS, the most active photocatalyst in this study. Photocatalytic activity test was conducted by varying tetracycline concentration, irradiation time, catalyst's concentration and pH using response surface methodology to find out the optimum condition for photocatalytic activity. The reusability of as-synthesized NST/CS was assessed which due to its high recoverability can be applied as an effective catalyst for degradation of organic substances in water and wastewater especially for degradation of emerging pollutants such pharmaceutical pollutants. The results from this work show a promising material for local authorities and pharmaceutical facilities to use for the treatment of pharmaceutical pollutants and tetracycline removal in water resource.

First-principle calculation of the electronic structures and optical properties of the metallic and nonmetallic elements-doped ZnO on the basis of photocatalysis

In the present paper, the electronic structure and the optical properties of metallic and nonmetallic elements-doped ZnO were investigated based on the principle of photocatalysis by first-principle density functional theory. Element doping shortens the band gap of ZnO. Due to the p-type characteristics, Fe, Cu, B and N doping brings impurity states over the Fermi level of ZnO, resulting in the shortening of the band gap, extending the absorption and utilization of solar light and thus enhancing the photocatalytic properties of ZnO. However, no impurity states appear in the band gap of Cd- and S-doped ZnO due to the intrinsic doping of Cd and S. Further investigations indicate that different doping atoms can indeed alter the near-Fermi level density of states (DOS) of ZnO and their electronic structures via substitution of zinc and oxygen atoms. In addition, the optical properties of ZnO are improved after doped with different atoms by comparing with those of pure ZnO. Due to the difference of their outer shell electrons of the doped atoms, the optical absorption properties of the investigated materials are followed as the following order: Fe-/B-doped ZnO > Cu-/N-doped ZnO > Cd-/S-doped ZnO > pure ZnO.

One-pot synthesis of the g-C3N4/S-doped ZnO composite with assistance of sodium lignosulfonate and its enhanced photodegradation on organic pollutants

Lignin is one of the most abundant materials in nature, but its highly value-adding utilization is still a challenge. Herein, sodium lignosulfonate (SLS) was adopted to fabricate ZnO centering on the concept of “using lignin valuably”. And the g-C3N4/S-ZnO (CNSZ) composite was successfully prepared. SLS serves as a linkage reagent, interacting with ZnO on one hand and simultaneously helping urea (processor of g-C3N4) to be deposited with ZnO. The structure and morphology of CNSZ were fully characterized. It is shown that g-C3N4 co-exists in the composite. Meanwhile, EDS and XPS analyses indicate the presence of S in the composite, which originates from SLS. The composite is found to show good photocatalytic property. Its degradation efficiency on phenol is 8.5 times higher than bare ZnO. Due to its facile synthesis and excellent property, the newly-synthesized CNSZ is anticipated to be promising for water treatment application.

Synthesis and Photoluminscence Properties of Morphology- and Microstructure-Controlled S-Doped ZnO Nanostructures

Synthesis and Photoluminscence Properties of Morphology- and Microstructure-Controlled S-Doped ZnO Nanostructures

Tunable Schottky contact humidity sensor based on S-doped ZnO nanowires on flexible PET substrate with piezotronic effect

Abstract A novel, flexible sulfur (S)-doped ZnO (ZnO:S) nanowire relative humidity (RH) sensor with a self-powered piezoelectric nanogenerator is proposed. A sensor based on ZnO NWs was also prepared. With a constant bias applied, the measured current of the sensor increased with increasing RH in the dark and under ultraviolet (UV) exposure. With an operating temperature of 50 °C and a loading weight of 12.5 g/cm 2 , the RH response of the sensor rapidly increased ∼3 orders of magnitude at 80% RH. The S dopant improved the RH sensing ability of ZnO nanowires. The sensitivity of the RH sensor can be tuned via the Schottky barrier height, which is affected by loading weight compressive strain. The sensor can also generate electrical power, with energy converted from environmental vibration. The ZnO:S nanowire piezoelectric nanogenerator outputs 11.6 and 18.6 nW in the dark and under UV exposure, respectively, under a loading weight of 12.5 g/cm 2 .

A novel fabrication methodology for sulfur-doped ZnO nanorods as an active photoanode for improved water oxidation in visible-light regime

Incorporation of foreign moiety in the lattice of semiconductors significantly alters their optoelectronic behavior and opens a plethora of new applications. In this paper, we report the synthesis of sulfur-doped zinc oxide (S-doped ZnO) nanorods by reacting ZnO nanorods with diammonium sulfide in vapor phase. Microscopic investigation revealed that the morphological features, such as, the length (2–4 μm) and width (100–250 nm) of the original hexagonal ZnO nanorods remained intact post-sulfidation. X-ray photoelectron spectroscopy analysis of the sulfide sample confirmed the incorporation of sulfur into ZnO lattice. The optical measurements suggested the extension of absorption threshold into visible region upon sulfidation. Photoelectrochemical (PEC) activities of pure and S-doped ZnO nanorods were compared for water oxidation in visible light (λ > 420 nm), which showed several-fold increment in the performance of S-doped ZnO sample; the observed amelioration in the PEC activity was rationalized in terms of preferred visible light absorption and low resistance of sulfide sample, as evidenced by optical and electrochemical impedance spectroscopy.

Synthesis of S-doped hierarchical ZnO nanostructures via hydrothermal method and their optical properties

Herein, hierarchical flower-like ZnO nanostructures and S-doped ZnO flower-like hierarchical nanostructures composed of porous nanosheets were synthesized via a one-step hydrothermal method. In this method, Zn(NO3)2·6H2O was used as a precursor and CS(NH2)2 was the dopant. Field emission scanning electron microscope (FESEM), Energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), UV–Vis absorption spectra and photoluminescence spectra (PL) were used to characterize the samples. It demonstrates that small portions of S are successfully incorporated into the lattice of the ZnO nanostructures. The incorporation of S into ZnO is supported by broadening and lower Bragg angle shift in XRD pattern and EDS analysis. Cell Parameters of hierarchical flower-like S-doped ZnO nanostructures are obtained from Rietveld Analysis. The results show that the molar ratio of Zn and S determines the structure, surface morphology and optical properties of the samples significantly. PL spectra show that the effective S doping enhances the green emission and suppresses the near band gap emission.

Photochemical Degradation of Diclofenac Sodium By Nanophotocatalyst ZnO Doped C, N, S in Aqueous Solution Using UV Irradiation

Novel C, N, and S-doped ZnO nanoparticles were prepared by a solid phase reaction. The catalyst was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The results showed that crystallite size of synthesized C, N, and S-doped ZnO were in nanoscale. The degradation was studied under different conditions such as the catalyst concentration, concentration of drug, initial pH value and presence of electron acceptor. The results showed that photocatalytic degradation of drug was strongly influenced by these parameters. The best conditions for the photocatalytic degradation of diclofenac sodium were obtained. The optimum concentrations of N, S, C -ZnO was found to be 0.44g/L. The photodegradation efficiency of diclofenac sodium decreased with an increase in the initial concentration of diclofenac sodium. In acidic solutions, photocatalytic degradation efficiency was higher than in alkaline solutions. The photodegradation efficiency of diclofenac sodium was accelerated by addition of a small amount of K2S2O8 and H2O2. Figure 1

Structural, optical and transport properties of SxZnO

In this paper, S-doped ZnO (SxZnO) was prepared using sol-gel method at different S amounts. The structural, optical and transport properties were investigated. The introduction of S atoms into the ZnO network was found to lower the crystallization level which results in reducing the crystallite size up to x=0.3. The doping process is confirmed by the observed peak at ~610cm−1 in the ATR spectrum related to the Zn-S linking. EDX mapping shows a homogeneous distribution of S atoms on the particles surface. The best compromise between the band gap (Eg=2.96eV), the charge carriers (NA=2.139×1022cm−3), the conductivity (σ=5.56×10−4Ω−1m−1) and the mobility (µ=16.26×10−14m2V−1s−1) is obtained for x=0.1. The conduction mechanism is assumed by small hopping polaron. The S-doping has impacted positively the photocatalytic activity of ZnO, with particularly high performance for S0.2ZnO.