Oxide ZnO Research Articles

Mesoporous ZnO@CO3O4 nanosphere for sensitive detection of 3-hydroxy-2-butanone

It is important to detect foodborne pathogens in food and water, such as Listeria monocytogenes (L.monocytrogenes), which can cause foodborne illness in people with compromised immune systems. Volatile organic compounds (VOC) and 3‑hydroxy-2-butanone (3H-2B) produced by L.monocytrogenes can be used as biomarkers for indirect detection of microbial contamination. In this study, the mesoporous ZnO@CO3O4 nanosphere was prepared through the simple hydrothermal synthesis method of ZIF-l-Zn@Co, the cage construction of mesoporous ZnO@CO3O4 nanosphere was remained unchanged after the calcination of the ZIF-l-Zn@Co at 600 °C for 2 h in air. The mesoporous ZnO@CO3O4 nanosphere was selected as the gas sensor showed the strongest response to 3H-2B, and 7–12 times higher than the response of other test gases. In addition, compared with ZnO and Co3O4 single metal oxide gas sensor, the ZnO@CO3O4 sensor possessed better repeatability and stability after repeated repeatability tests under the same conditions.

Synthesis and Characterization of Ternary BexZn1-xO Nano Thin Films prepared by Pulsed Laser Deposition Technique

Beryllium Zinc Oxide (BexZn1-xO) ternary nano thin films were deposited using the pulsed laser deposition (PLD) technique under a vacuum condition of 10-3 torr at room temperature on glass substrates with different films thicknesses, (300, 600 and 900 nm). UV-Vis spectra study found the optical band gap for Be0.2Zn0.8O to be (3.42, 3.51 and 3.65 eV) for the (300, 600 and 900nm) film thicknesses, respectively which is larger than the value of zinc oxide ZnO (3.36eV) and smaller than that of beryllium oxide BeO (10.6eV). While the X-ray diffraction (XRD) pattern analysis of ZnO, BeO and Be 0.2 Zn 0.8 O powder and nano-thin films indicated a hexagonal polycrystalline wurtzite structure. The crystal structure showed a preferential orientation line at (101). Besides the nano thin film Be0.5Zn0.5O has all orientations of ZnO and BeO. Moreover, the calculated average crystallite size for nano thin film was 16.48 nm. The surface morphology of the nano thin films investigated by atomic force microscope (AFM) showed a decrease in the average grain sizes (94.8, 79.2 and 59.4 nm) with the increase of films thickness due to quantum confinement effect.

Study of zinc salt concentration effect on the growth of zno nanostructured oxides obtained by direct electrodeposition

"Effect of zinc salt concentration on the growth of electrodeposited zinc oxide phases was investigated. ZnO thin films were elaborated via chronoamperometry on fluorine doped tin oxide (FTO) substrates from aqueous mixed bath of zinc nitrate and chlorate at 70°C. X ray diffraction patterns showed nanocrystalline films of hexagonal wurtzite phase with (101) preferential orientation for ZnO as grown in low concentration of Zn2+ salt. High concentration of Zn2+ favor the formation of Zn5(OH)8Cl2H2O simonkolleite phase. After heat treatment at 400 °C for 1h this later decomposes to ZnO oxide which presents no preferential orientation. The route mean square RMS roughness of surfaces estimated from AFM technique shows that ZnO generated from heat treated Zn5(OH)8Cl2H2O present more increasing roughness than ZnO deposits obtained at lower salt concentration. The photoelectrochemical answer indicated important generated photocurrents for both films which present n-type electrical conductivity"

Improving the absorption spectrum and performance of CIGS solar cells by optimizing the stepped band gap profile of the multilayer absorber

In this paper, we investigate a way to improve the performance of thin films CIGS-based solar cells by optimizing their spectral responses. Band gap profile grading, aroused this last decade as a very promising strategy to achieve higher efficiency. This work was performed on a CIGS-based thin-film solar cell model, using cadmium sulphide CdS as a buffer layer, with zinc oxide ZnO as window layer. Focusing on electrical properties such as band gap and electron susceptibility, we modified gallium content of the absorber layer of a reference cell. Using aforementioned band gap grading strategy, we stacked three CIGS layers with different gallium contents, and we modelled a stepped band gap profile using SCAPS-1D. The comparative analysis of the results obtained through numerical simulation, with those of six different band gap profiles of the absorber layer, supports the statement that, stepped band gap profile is a promising approach for engineering improvement of high-efficiency CIGS-based solar cells. In fact, the absorption spectrum of the optimized cell has improved compared to the other band gap profiles simulated in this work; with a peak external quantum efficiency (EQE) of 94%. Efficiencies losses dues to recombination were reduced and the generated photocurrent is higher than that of classical profiles. Record efficiency of 28.03% was achieved with a fill factor of 86.42%. We believe absorber layer stacked in a stepped band gap profile, as a complementary approach to improve performances, is definitely a must-have technology for all future generations high efficiency thin films solar cells.

Role of modifiers on the structural, mechanical, optical and radiation protection attributes of Eu3+ incorporated multi constituent glasses

The effect of modifiers on the optical features and radiation defying ability of the Eu3+ ions doped multi constituent glasses was examined. XRD has established the amorphous nature of the specimen. The presence of various functional/fundamental groups in the present glasses was analyzed through FTIR spectra. The physical, structural and elastic traits of the glasses were explored. The variation in the structural compactness of the glass structure according to the incorporated modifier was enlightened to describe their suitability for a better shielding media. For the examined glasses, the metallization criterion value varied in the range 0.613–0.692, indicating the non-metallic character of the glasses with possible nonlinear optical applications. The computed elastic moduli expose the Li-containing glass (BTLi:Eu) to be tightly packed and rigid, which is a requirement for a better shielding channel. Furthermore, the optical bandgap and the Urbach energy values are calculated based on the optical absorption spectra. The evaluated bonding parameters revealed the nature of the fabricated glasses covalent. In addition, we investigated the radiation attenuation attributes of the prepared Eu3+ ions doped multi constituent glasses using Phy-X software. We determined the linear attenuation coefficient (LAC) and reported the influence of the five oxides Li2O3, CaO, BaO, SrO, and ZnO on the LAC values. The LAC varied between 0.433 and 0.549 cm−1 at 0.284 MeV. The 39B2O3−25TeO2−15Li2O3−10Na2O−10K2O −1Eu2O3 glass has a much smaller LAC than the other glasses.

N-type polysilicon passivating contact combined with hydrogen-containing TCO as the interconnected structure for perovskite/silicon tandem solar cells

An interconnected structure of perovskite/silicon tandem solar cell is the key point to accomplishing high efficiency over 30% due to its high performance of carrier recombination and tunneling. In general, an interconnected structure is designed by a polysilicon (poly-Si) passivating contact structure and a hydrogen-containing transparent conductive oxides (TCO). When the bottom cell structure was fabricated in mass production, poly-Si passivating contact inevitably suffered from a degradation of the passivation quality associated with the metallization firing process. In this work, we investigated the effect of hydrogen-containing indium tin oxide (ITO:H) and Al-doped ZnO (AZO:H) prepared by dc magnetron sputtering on poly-Si passivating contacts passivation degradation. The passivation quality of the poly-Si passivating contacts can be significantly improved by sputtering and annealing at 350 °C after firing of both the hydrogen-containing TCOs. The improvement on poly-Si passivating contacts passivation quality increased with the increased of annealing dwell time. When at the optimal annealing time of 30 min, the iVoc value of ITO:H increased to 725 mV while that of AZO:H increased to 710 mV, respectively. In addition, the optical and electrical properties of ITO films can be improved by annealing process, including transmittance, optical bandgap, Hall mobility and resistivity. When the annealing time is less than 30min, the contact resistivity between Ag/ITO and doped poly-Si increases slightly with the increase of annealing time. However, the optical and electrical properties of AZO films degraded, which may be due to the instability of the prepared AZO:H films. Eventually, based on this interconnected structure, a perovskite/Si tandem cell structure was designed, and silicon substrate cells could be fabricated in mass production.

Simulation and Comparison of Current-Voltage Characteristics in Double Gate Nanowire FET Using ZnO and SiO2 as Gate Oxide Materials

The aim of the project is to simulate and compare current-voltage characteristics in double gate nanowire field effect transistors made of ZnO and SiO2 gate oxides with thicknesses ranging from 1 to 30 nm. Materials and methods: The drain characteristics of double gate nanowire FET for the two gate oxides were considered for analysis. Altogether 147 drain current samples were considered for each group. Results: The two groups are subjected to an independent sample test using SPSS software, which calculates the significant mean value. The SPSS tool's chart builder is used to create a statistical graph. The mean for those in the highest quartile of drain current of ZnO based DG NW FET (drain current=0.461 mA, 95% CI:0.232-0.458 mA, p<0.05), but in SiO2 based DG NW FET (drain current=0.115 mA, 95% CI:0.232-0.458 mA, p<0.05). Conclusion: ZnO nanowire field-effect transistors have better switching characteristics and higher drain current than SiO2. The drain current is altered by varying the oxide thickness of the material. The drain current of ZnO is significantly higher than that of SiO2.

Structure, optical properties, and ionizing radiation shielding performance using Monte Carlo simulation for lead-free BTO perovskite ceramics doped with ZnO, SiO2, and WO3 oxides

This study reports the influence of different oxides doping on the structure, optical characteristics, and radiation protecting performances of perovskite BaTiO3 (BT used thereafter) ceramic synthesized by solid-state reaction process. The crystal structure and phase identification are examined through X-ray diffraction technique (XRD) and Rietveld refinement analyses that confirm a monophasic tetragonal structure with a P4mm space group in BT ceramic. The tetragonality is maintained with ZnO doping, however, for ceramics doped with WO3 and SiO2, a cubic structure is detected with the presence of some impurities. The variation in the structural parameters is indicative of the distortion in the unit cell under the influence of different oxides doping. The optical properties reveal a variation in optical bandgap under the effect doping. The values of Eg follow the order of BT: Zn < BT < BT: W < BT: Si. BT doped with SiO2 exhibits a wider bandgap energy (3.41 eV) compared to all prepared ceramics. The radiation shielding studies were examined using Monte Carlo simulation. The linear attenuation coefficient (μ) values for BaTiO3 are 1.238, 0.453, and 0.297 cm−1 for photons with energies 0.244, 0.662, and 1.332 MeV, respectively, and these values were increased gradually with the addition of ZnO or WO3 metal oxides. In contrast, the addition of SiO2 compounds to the basic composition BT causes a reduction in both the density and shielding capacity of the fabricated BT. The half-value thickness (Δ0.5) was evaluated and the results demonstrated that the Δ0.5 increases between 0.560 and 2.399 cm (for BT ceramics), 0.555–2.370 cm (for BT: Zn), 0.528–2.293 cm (BT: W), and 0.609–2.619 cm (for BT: Si ceramics) when the γ-ray energy raised between 0.244 and 1.408 MeV, respectively. Also, the addition of ZnO and WO3 slightly enhance the Δ0.5 values by a factor of 1.142% and 4.532%. On the other hand, the addition of the SiO2 compound to BaTiO3 increases the Δ0.5 value by a factor of 9.16%.

Highly efficient quantum-dot-sensitized solar cells with composite semiconductor of ZnO nanorod and oxide inverse opal in photoanode

Photoelectric conversion is realized by a series of processes in quantum-dot-sensitized solar cells (QDSSCs), including light capture, photoelectron generation, and electron transmission. In addition to obtaining photoelectrons, the photoanode provides a channel for electron transmission. Therefore, the photoanode plays important roles in improving the performances of QDSSCs. This paper presents the fabrication of a novel photoanode based on a semiconductor composite of ZnO nanorods and TiO2/ZnO inverse opal. QDSSCs with composite semiconductors of ZnO nanorods and oxide inverse opal in the photoanode were demonstrated to facilitate better charge transfer and reaction rates at the interface and obtain higher photocurrents and power conversion efficiencies than those of QDSSCs with pure inverse opal photoanodes. Using a CdS/CdSe co-sensitizer in the QDSSCs, a maximum cell efficiency of 8.18% was obtained, and it was further improved to 11.24% after interface modification with NH4F and ZnS.

Structural evolution and catalytic performance in CO2 hydrogenation reaction of ZnO-ZrO2 composite oxides

ZnO-ZrO2 composite oxides are used as catalysts for CO2 hydrogenation reaction. Herein, we prepare a series of ZnO-ZrO2 composite oxides via co-precipitation method and comprehensively study their structural evolution and catalytic performance in CO2 hydrogenation reaction. Via combined spectroscopic and microscopic characterization techniques, we found that, as the Zr content increased, phase structures of ZnO-ZrO2 composite oxides evolved from the mixture of hexagonal ZnO phase and Zn-doped ZrO2 solid solution phases to the pure Zn-doped ZrO2 solid solution phase. Zn-doped ZrO2 solid solution nanoparticles of mixed-phased ZnO-ZrO2 composite oxides were observed to preferentially nucleate and grow within the bulk of ZnO nanoparticles. Surfaces of mixed-phased ZnO-ZrO2 composite oxides are enriched with Zn, while the pure Zn-doped ZrO2 solid solutions exhibit uniform bulk and surface compositions. ZnO-ZrO2 composite oxides are much more catalytic active than pure ZnO, t-ZrO2 and m-ZrO2 in catalyzing CO2 hydrogenation reactions. The pure Zn-doped ZrO2 solid solution phase exhibit high selectivity toward CH3OH production, while pure ZnO, t-ZrO2, m-ZrO2 and mixed-phased ZnO-ZrO2 composite oxides exhibit high selectivity toward CO production. Bidentate formate species and carbonates/bicarbonates species are the key intermediates of the CO2 hydrogenation to methanol and CO, respectively. These results deepen the fundamental understanding of structure–activity relation and reaction mechanisms for ZnO-ZrO2 composite oxides-catalyzed CO2 hydrogenation reaction.

X-ray peaks profile analysis, optical and cathodoluminescence investigations of cobalt-doped ZnO nanoparticles

Effects of Co doping on the structural and optical properties of ZnO oxide nanoparticles (NPs) prepared by a solvothermal method are reported. X-ray diffraction examinations using Rietveld refinement confirms the hexagonal wurtzite symmetry ZnO phase nanostructure belonging to P63mc space group. No segregated secondary phases or Co rich clusters were detected. The X-ray diffraction peaks shifts towards higher angle gradually as the concentration of nominal Co content increases in ZnO. This shifting in peak position reflect that Co is well replaced Zn in ZnO matrix. With increasing the Co content to 3%, both lattice parameters a and c of the hexagonal ZnO tended to gradually decrease, suggesting substitutional doping of Co at the tetrahedral Zn2+sites. For Co loading of5%, these trends reversed and the lattice showed a gradual expansion, which is explained by additional interstitial incorporation of Co. The Williamson-Hall (W–H) method with various models i.e. uniform deformation model (UDM), uniform stress deformation model (USDM) and uniform deformation energy density model (UDEDM), as well as size-strain plot (SSP) method, and the morphological observations using transmission electron microscopy (TEM) image were used to evaluate the crystallite size as well as the lattice strain. Optical studies carried out by diffuse reflectance spectroscopy (DRS) indicated a decrease in the value of the band gap from 3.238 eV to 2.993 eV with increasing Co doping concentration. The obtained results are confirmed by cathodoluminescence technique.

An attempt to tailor methane oxidation behaviors over Pd/Al2O3 systems through the concerted fashion of Zn and alkaline-metal promoters

Aiming to manipulate the properties of Pd/Al2O3 catalysts towards CH4 oxidation, trace of Zn and alkaline-earth metal (X = Mg, Ca, Sr and Ba) were dual-doped into mesoporous alumina. This was mainly inspired by their multi-functionality, in terms of the feature of semiconductor structure from amphoteric oxide ZnO, the higher metallicity and electron-donating effect from alkaline-earth metals, and the ability from both Zn and alkaline-earth metals to generate spinel phase with alumina. Eventually, the electron density throughout oxygen and metal atoms underwent rearrangement, the interfacial interaction and the surface work function of catalysts were altered. This in turn gave the distinction in the nanoparticle sizes and reducibility of palladium oxides, surface-concentration and stability of active PdO, distribution of surface oxygen species, and surface acid-base functionalities along the series of catalysts. Results demonstrated that the trade-off of these entire properties allowed Pd/ZnMg-MA with maximum light-off activity, whilst affording minimum drop in methane conversion over both Pd/ZnMg-MA and Pd/ZnBa-MA not only during long-term online test but also when water was injected into the feed.

The Effect of Oxygen and Air Flow on the Characteristic of Zinc Oxide ZnO Nanorods

In this study, ZnO nanorods are synthesized by the means of chemical bath deposition (CBD). Further objectives, to study the effect of new parameters (oxygen and air flow) on ZnO nanorods on morphology and length of alignment of the nanorods. It was observed that 0.100M for both zinc nitrate hexahydrate and hexamethylenetetramine give a best result. Here, we added an oxygen gas pressure as others idea in chemical bath deposition method and a p-type silicon substrate to investigate the length of ZnO nanorods through their cross-section. It was found that the biggest grain sizes obtain from sample 14, which is 58.87nm produces a high crystal quality, among others. Sample 14 also has a long nanorods (1.434μm-1.451μm) compared to other samples. The hexagonal structure was observed by Field Emission Scanning Electron Microscope, FESEM and well aligned, compact and perpendicular ZnO nanorods grew on the surface of glass substrate. XRD data shows that it has a larger grain size with low lattice strain. The cross-sectional view of the samples demonstrates long nanorods with a range 2.763μm-2.844μm. Finally, the growth of ultra-long ZnO nanorods by using a modified chemical bath setup was successfully observed and recorded.Keywords: ZnO nanorods, CBD, Growth duration, FESEM images, pressure flow.

Nanoscale-Resistive Switching in Forming-Free Zinc Oxide Memristive Structures.

This article presents the results of experimental studies of the impact of electrode material and the effect of nanoscale film thickness on the resistive switching in forming-free nanocrystalline ZnO films grown by pulsed laser deposition. It was demonstrated that the nanocrystalline ZnO film with TiN, Pt, ZnO:In, and ZnO:Pd bottom electrodes exhibits a nonlinear bipolar effect of forming-free resistive switching. The sample with Pt showed the highest resistance values RHRS and RLRS and the highest value of Uset = 2.7 ± 0.4 V. The samples with the ZnO:In and ZnO:Pd bottom electrode showed the lowest Uset and Ures values. An increase in the number of laser pulses from 1000 to 5000 was shown to lead to an increase in the thickness of the nanocrystalline ZnO film from 7.2 ± 2.5 nm to 53.6 ± 18.3 nm. The dependence of electrophysical parameters (electron concentration, electron mobility, and resistivity) on the thickness of the forming-free nanocrystalline ZnO film for the TiN/ZnO/W structure was investigated. The endurance test and homogeneity test for TiN/ZnO/W structures were performed. The structure Al2O3/TiN/ZnO/W with a nanocrystalline ZnO thickness 41.2 ± 9.7 nm was shown to be preferable for the manufacture of ReRAM and memristive neuromorphic systems due to the highest value of RHRS/RLRS = 2307.8 ± 166.4 and low values of Uset = 1.9 ± 0.2 V and Ures = −1.3 ± 0.5 V. It was demonstrated that the use of the TiN top electrode in the Al2O3/TiN/ZnO memristor structure allowed for the reduction in Uset and Ures and the increase in the RHRS/RLRS ratio. The results obtained can be used in the manufacturing of resistive-switching nanoscale devices for neuromorphic computing based on the forming-free nanocrystalline ZnO oxide films.

Gamma irradiation effectuality on the antibacterial and bioactivity behavior of multicomponent borate glasses against methicillin-resistant Staphylococcus aureus (MRSA).

Recently some borate bioactive glasses have been discovered to have an antibacterial effect when interacting with pathogenic bacteria. In this study, borate bioactive glasses (BG) doped with metal oxide (MO) ZnO, TiO2, TeO2, and CeO2 (encoded BG-Zn, BG-Ti, BG-Te, and BG-Ce, respectively) were prepared using the melt-quench method and have been characterized before and after gamma irradiation at 25.0kGy. X-ray diffraction was performed to recognize the amorphous phases of all samples. Infrared absorption of glasses confirms vibrational bands in their wave number according to mixed main triangular and tetrahedral borate groups. After immersion in the simulated body fluid (SBF) solution, two characteristic peaks are generated indicating the bioactivity of the studied glasses through the formation of hydroxyapatite. SEM micrographs of glass after immersion display that the crystalline phases are identified to be more distinct in different shapes because of the multi-composition involved. The antibacterial activity of borate glasses was assessed against methicillin-resistant Staphylococcus aureus (MRSA) ATCC 6538. The antibacterial results showed that BG-Te was the most efficient against S. aureus ATCC 6538. Furthermore, BG-Te reduced biofilm production (79.23%) at the concentration of 20.0mg/mL. (BG-Te) at 20.0mg/mL significantly decreased the viability percent, cell count, protein content, and protease activity of S. aureus cells. BG-Te presents powerful activity against bacterial infections. It was necessary to equilibrate the antibacterial efficiency with the biocompatibility, so the MTT assay confirmed that BG-Te has low cytotoxicity on the human fibroblast cells (WI-38). It is expected that borate bioglass contained TeO2could be a promising biomaterial for bone tissue engineering.

Structure and Photocatalytic Activity of Copper and Carbon-Doped Metallic Zn Phase-Rich ZnO Oxide Films

ZnO is one of the most important industrial metal oxide semiconductors. However, in order to fully realise its potential, the electronic structure of ZnO has to be modified to better fit the needs of specific fields. Recent studies demonstrated that reactive magnetron sputtering under Zn-rich conditions promotes the formation of intrinsic ZnO defects and allows the deposition of metallic Zn phase-rich ZnO films. In photocatalytic efficiency tests these films were superior to traditional ZnO oxide, therefore, the purposeful formation of intrinsic ZnO defects, namely Zn interstitials and oxygen vacancies, can be considered as advantageous self-doping. Considering that such self-doped ZnO remains a semiconductor, the natural question is if it is possible to further improve its properties by adding extrinsic dopants. Accordingly, in the current study, the metallic Zn phase-rich ZnO oxide film formation process (reactive magnetron sputtering) was supplemented by simultaneous sputtering of copper or carbon. Effects of the selected dopants on the structure of self-doped ZnO were investigated by X-ray diffractometer, scanning electron microscope, X-ray photoelectron spectroscope and photoluminescence techniques. Meanwhile, its effect on photocatalytic activity was estimated by visible light activated bleaching of Methylene Blue. It was observed that both dopants modify the microstructure of the films, but only carbon has a positive effect on photocatalytic efficiency.

Low-cost processing of pure and Al-doped capped ZnO nano powder for industry scale applications C

Zinc oxide and metal-doped oxides are multifunctional nanomaterials used in the Nano World due to their distinctive characteristics and unique physical and chemical properties such as extraordinary chemical stability, anti-corrosion, low electrons conductivity, a broad range of radiation absorption, high photo stability, and tremendous heat resistance. To synthesize zinc oxide and Al-doped ZnO nanostructures with the inexpensive sol-gel method is our research objective, further we aimed to analyse the characterization of undoped and Al-doped ZnO nanopowder. Al-doped zinc oxide with compositional formula AlxZn1-xO (x = 0, 2, 4, 6) was synthesized using Zinc acetate dihydrate (Zn (CH3COO)2. 2H2O) as a precursor, Sodium hydroxide (NaOH) and distilled water were used as a second-hand medium for the preparation of the solution. Ethanol (CH2COOH) served as a versatile intermediate and was used as a solvent. The X-ray diffraction peaks suggest a hexagonal wurtzite crystal structure which matches with the pattern of the standard hexagonal structure of ZnO and Al-doped zinc oxide in all samples. X-ray diffraction result exhibits good crystallinity. The scanning electron microscopy images confirm the clear formation of spherical ZnO nanopowder and the change of the morphology of the nanopowder with the incorporation of the aluminium. The scanning electron microscopy results are in adjacent settlement with that estimated by the DebyeSheerer formula created on the X-ray diffraction pattern. The usual crystallite size of Aldoped zinc oxide decreases by an increase in Al concentration with capping without varying the temperature. X-ray diffraction and scanning electron microscopy with energy dispersive x-ray analysis revealed that all samples crystallize in polycrystalline nature with wurtzite lattice. The result of energy dispersive x-ray analysis characterization shows that the ZnO nanopowders with no other main adulterated phase. Extant learning ventures this as a low-cost method for the synthesis of pure and capped Al-doped ZnO for industry scale applications.

Manganese (Mn2+) Doped Hexagonal Prismatic Zinc Oxide (Zno) Nanostructures by Hydrothermal Route for Chemiresistive Measure of No2

Manganese (Mn2+) Doped Hexagonal Prismatic Zinc Oxide (Zno) Nanostructures by Hydrothermal Route for Chemiresistive Measure of No2

A Comparative Theoretical Study of ZnO and BeO Oxides in Terms of Electronic Properties

A Comparative Theoretical Study of ZnO and BeO Oxides in Terms of Electronic Properties

Synthesis, Characterization and Application of Chitosan-TPP-ZnO Nanocomposite for Efficient Treatment of Effluent Containing Sulphur Dye

In this present study, an attempt has been made to synthesize Chitosan-TPP (sodium tripolyphosphate)-ZnO (CT/ZnO) nanocomposite for wastewater treatment to enhance the degradation of dyes and harmful compounds in effluent water. CT/ZnO nanocomposite was synthesized by a very facile method of chemical precipitation at room temperature. The structural, morphological, optical, elemental and thermal properties of CT/ZnO nanocomposite were studied using X-ray Diffraction (XRD), High-Resolution Scanning Electron Microscopy (HRSEM), UV–visible-Diffuse Reflectance Spectroscopy (UV–vis-DRS), Fourier Transform Infrared (FTIR) Spectroscopy, X-ray Photoelectron Spectroscopy (XPS), Thermogravimetric Analysis/Differential Thermal Analysis (TGA/DTA) and Differential Scanning Calorimetry (DSC). XRD analysis showed the crystalline nature of CT/ZnO nanocomposite and confirmed the crystal structure as hexagonal primitive. The average crystallite size calculated using Debye Scherrer’s formula was found to be 42 nm. HRSEM images revealed the agglomeration of nanoparticles which resulted in increased particle size. Energy Dispersive X-ray Spectroscopy (EDAX) performed along with HRSEM confirmed the purity of CT/ZnO nanocomposite. UV–vis-DRS analysis displayed peaks corresponding to chitosan and ZnO nanoparticles in the UV region, which suggests that ZnO nanoparticles had dispersed well into the chitosan nanoparticle system. This nanocomposite could be used effectively in UV screening. FTIR and XPS results exhibited enhanced interaction between the amine groups of chitosan and the metal oxide ZnO in the nanocomposite. The three-step mass reduction was observed in the TGA thermogram of the sample which was in good agreement with DTA and DSC thermograms and displayed good thermal stability at ambient conditions. CT/ZnO nanocomposite showed efficient decolourization of effluent water due to the combined effect of the adsorption, photocatalysis and coagulation.