Doped Zinc Oxide Research Articles

Versatile eco-friendly electrochemical sensor based on chromium-doped zinc oxide nanoparticles for determination of safinamide aided by green assessment criteria

Safinamide, a highly selective monoamine oxidase B inhibitor, is currently used as a monotherapy or as add-on therapy to levodopa for the treatment of Parkinson’s disease. A selective, ecofriendly, voltammetric method was developed for the determination of safinamide. A new nanotechnology-based sensor was fabricated and fully characterized using different techniques (scanning electron microscopy, transmission electron microscopy and X-ray diffraction). The designed electrode, chromium doped-zinc oxide nanoparticles/modified carbon paste electrode, displayed a wide dynamic linear range 0.5 – 20 µg/mL alongside a good sensitivity with an LOD of 162 ng/mL. The inclusion of the electrode with chromium doped zinc oxide nanorods (Cr/ZnO-NPs) increases its surface area, the number of active sites available for interaction with Safinamide. The best sensitivity was achieved using an optimum electrode composition 11 % chromium efficiently incorporated into ZnO nanoparticles relative to carbon paste. The good sensitivity could be attributed to increase in the electrode surface area which in turn linked to doping with chromium. Hence, doping of chrome augment the surface area, thus chromium doped ZnO nanoparticles exhibit high surfacearea, and good thermal stability, which is a remarkable nanomaterial characteristic. The developed method exhibited high selectivity for the determination of Safinamide in presence of its co-administered drug (l-Dopa). The fabricated sensor was utilized in Safinamide quantitation in commercial tablets, and human plasma. Method greenness was validated using Analytical Eco-Scale methodology.

A promising antimicrobial bionanocomposite based poly(3-hydroxybutyrate-co-3-hydroxyvalerate) reinforced silver doped zinc oxide nanoparticles

A bionanocomposite based on biosynthesized poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and reinforced with silver@zinc oxide (Ag–ZnO) was synthesized in variable loadings of Ag–ZnO using the in-situ casting dissolution technique. The degradable biopolymer PHBV had been biosynthesized from date waste as a renewable carbon source. The fabricated products were investigated as promising antibacterial materials. The Ag–ZnO nanoparticles were also synthesized using the green method in the presence of Gum Arabic. The Ag–ZnO nanoparticles were loaded within the PHBV biopolymer backbone at concentration of 1%, 3%, 5% and 10%, PHBV/Ag–ZnO(1,3,5,10%). The chemical structure, morphology, physical and thermal properties of the PHBV/Ag–ZnO bionanocomposites were assessed via common characterization tools of FTIR, TGA, XRD, SEM and EDX. One step of the degradation process was observed in the range of 200–220 °C for all the obtained materials. The onset degradation temperature of the bionanocomposites have been noticeably increased with increasing the nanofiller loading percentage. In addition, fabricated products were investigated for their interesting antibacterial performance. A detailed biological screening for the obtained products was confirmed against some selected Gram-positive and Gram-negative strains S. aureus and E. coli, respectively. Overall, the bionanocomposite PHBV/Ag–ZnO(10%) was the most potent against both types of the selected bacteria. The order of bacterial growth inhibition on the surface of the fabricated bionanocomposites was detected as follows: PHBV/Ag–ZnO(10%) > PHBV/Ag–ZnO(5%) > PHBV/Ag–ZnO(3%) > PHBV/Ag–ZnO(1%).

Optimizing the Morphology, Structure and Optoelectronic Properties of Aluminum Doped Zinc Oxide Thin Films Developed via Wet Chemical Synthesis

Transparent conducting oxides (TCOs) are wide band gap semiconductors having found their use in optoelectronics, flexible electronics, flat panel displays, electrochromic windows, transparent heater windows, and many more. Aluminum (Al) doped zinc oxide (AZO) is an important TCO material which is being widely investigated for such applications. Its optoelectronic properties can be tuned by adjusting the Al content. In this work we study the variation patterns of the electrical conductivity and the optical transparency of AZO thin films with altering the Al content between 0 and 8 at%. The AZO thin films were prepared by wet chemical synthesis from its stabilized sol of zinc acetate dihydrate and aluminum nitrate nonahydrate dissolved in an ethanol and methanol mix. The morphological, electrical, and optical characteristics of these films were explored employing optical microscopy, Hall effect measurements, and UV-Vis-NIR spectrophotometry, respectively. We found out that annealing induces cracks into the AZO thin films and can severely degrade its electrical conductivity. Therefore, it’s imperative to control the Al content as well as the film morphology and structure. Before studying the effects of the Al content, the cracks were mitigated by optimizing the deposition and annealing conditions. The films were spin coated from its sol at 3000 RPM for 30 seconds. The films were dried at 100 °C and were subsequently annealed at 450°C. Since annealing induced cracks, therefore three coats were applied and annealed each time to mitigate the number of transverse cracks across the thickness of the film. The crack minimization was also confirmed by the enhancement in electrical conductivity. For the uniform crack-free AZO films, the Al doping was found to significantly modify the electronic behavior of the films. We expect an initial increase in the conductivity up to around 2 at% Al doping beyond which a decrease in conductivity is expected due to Al2O3 formation.

Green Facile Synthesis of Silver-Doped Zinc Oxide Nanoparticles and Evaluation of Their Effect on Drug Release.

Silver doped zinc oxide nanoparticles (ZANPs) were synthesized by the gelatin mediated and polymerized sol-gel method, and a calcination temperature of 700 °C was applied for 2 h. X-ray diffraction (XRD), FESEM, TGA, DSC, and EDS were performed to study the structure of the prepared nano-powders. Both cubic silver and hexagonal ZnO diffraction peaks were detected in the XRD patterns. The XRD results, analyzed by the size strain plot (SSP) and Scherrer methods, showed that the crystalline sizes of these nanoparticles increased as the Ag concentration increased. The results were observed via transition electron microscopy (TEM), where the particle size of the prepared samples was increased in the presence of silver. Catechin was chosen as a drug model and was loaded into the hydrogels for release studies. The drug content percentage of catechin in the hydrogels showed a high loading of the drug, and the highest rate was 98.59 ± 2.11%, which was attributed to the Zn0.97Ag0.03O hydrogels. The swelling of the samples and in vitro release studies were performed. The results showed that Zn0.91Ag0.09O showed the highest swelling ratio (68 3.40%) and, consequently, the highest release (84) within 300 min. The higher amount of silver ions in the hydrogel structure causes it to enhance the osmotic pressure of the inner structure and increases the relaxation of the structure chain.

Mechanochemically induced synthesis of N-ion doped ZnO: solar photocatalytic degradation of methylene blue

ABSTRACT N-ion doped zinc oxide was synthesized by the mechanochemically induced solvent-deficient method using zinc nitrate hexahydrate and ammonium bicarbonate as the precursors. The synthesis was carried out using different calcination temperatures to investigate the dependence of how calcination temperature affects the crystal structure, bandgap, and photocatalytic activity of the zinc oxide doped with nitrogen. The morphological, structural, and optical properties of ZnO were investigated by thermal analysis (TG/DSC), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), diffuse reflectance spectroscopy (DRS), scanning electronic microscopy (SEM), X-ray Photoelectron Spectroscopy (XPS), and N2 adsorption-desorption (BET). Photocatalytic properties of synthesized materials were determined by methylene blue (MB) degradation in an aqua medium exposed to sunlight. N-ion doped zinc oxide samples calcined at 400, 500, and 600°C are found to be highly efficient photocatalysts, with the MB almost completely degraded after 180 min. Per contra, N-ion doped zinc oxide sample calcined at 300°C is found to be less efficient, most likely caused by different defect chemistry.

Synergistic Influences of Doping Techniques and Well‐Defined Heterointerface Formation to Improve the Photocatalytic Ability of the S‐ZnO/GO Nanocomposite

AbstractEnvironmental pollutants such as organic dyes are major focal areas of the current era. For this reason, excellent photocatalytic substances are needed time to degrade such water bodies and get pollution‐free water. In this study, Sulphur doped zinc oxide nanoparticles were fabricated utilizing a solution‐free technique, while graphene oxide was synthesized using a modified hummer‘s method. Sulphur‐doped zinc oxide nanoparticles were mixed with graphene oxide in five distinct weight percentages to achieve the S‐ZnO/GO (SZO) composites. The 8 % SZO NC demonstrated superior photocatalytic efficiency, degrading 100 % of MB in 110 minutes under sunlight irradiation. The synthesized composites were characterized by the techniques viz. TEM, SEM, EDXS, FTIR, XPS, and UV spectrophotometry to determine their chemical nature and morphological features. Methylene blue was used as a reference pollutant to evaluate the photocatalytic activity of the composites. According to the radical scavenger‘s test observations, •OH and •O2– were the primary species responsible for MB decomposition. Furthermore, the nanocomposites were found highly stable, with a continuously high degree of dye degradation throughout six catalytic cycles. As a result, the SZO nanocomposites have the prospective to be an extremely effective and versatile photocatalyst for the photodegradation of organic wastes.

Fabrication and Characterization of Acute Myocardial Infarction Myoglobin Biomarker Based on Chromium-Doped Zinc Oxide Nanoparticles.

In this article, we describe the fabrication and characterization of a sensor for acute myocardial infarction that detects myoglobin biomarkers using chromium (Cr)-doped zinc oxide (ZnO) nanoparticles (NPs). Pure and Cr-doped ZnO NPs (13 × 1017, 20 × 1017, and 32 × 1017 atoms/cm3 in the solid phase) were synthesized by a facile low-temperature sol-gel method. Synthesized NPs were examined for structure and morphological analysis using various techniques to confirm the successful formation of ZnO NPs. Zeta potential was measured in LB media at a negative value and increased with doping. XPS spectra confirmed the presence of oxygen deficiency in the synthesized material. To fabricate the sensor, synthesized NPs were screen-printed over a pre-fabricated gold-coated working electrode for electrochemical detection of myoglobin (Mb). Cr-doped ZnO NPs doped with 13 × 1017 Cr atomic/cm3 revealed the highest sensitivity of ~37.97 μA.cm−2nM−1 and limit of detection (LOD) of 0.15 nM for Mb with a response time of ≤10 ms. The interference study was carried out with cytochrome c (Cyt-c) due to its resemblance with Mb and human serum albumin (HSA) abundance in the blood and displayed distinct oxidation potential and current values for Mb. Cr-doped ZnO NP-based Mb biosensors showed 3 times higher sensitivity as compared to pure ZnO NP-based sensors.

Breakdown behavior of SiC photoconductive switch with transparent electrode

The breakdown behavior of a V-doped 4H silicon carbide photoconductive switch with a transparent electrode under a high electric field is studied. The device is triggered by a laser pulse below the bandgap wavelength with a repetition rate of 100 Hz. The light peak-power of the laser pulse reaches hundreds of kW, and the bias voltage is increased from 10 to 20 kV. With the accumulation of the number of pulses, the device shows breakdown behavior. Through the microscopic diagnosis of damaged and breakdown devices, according to the analysis of theoretical and simulation results, the breakdown of the device is due to the interaction between the laser and the aluminum doped zinc oxide transparent electrode on the device surface, resulting in the melting of the transparent electrode. The direct illuminate of the laser can form a field enhancement effect at the junction of the substrate and the transparent electrode, resulting in the damage of the device and the formation of pre-breakdown. Finally, the breakdown of the device inevitably occurs.

Optimization and development of ITO-free plasmonic gold nanoparticles assisted inverted organic solar cells

We report an indium tin oxide (ITO) free inverted organic solar cell with an alternate aluminium doped zinc oxide (AZO) front cathode layer based on the consideration of blocking harmful ultraviolet (UV) rays, which is one of the prominent reasons for degradation of organic solar cells. To further enhance the power conversion efficiency of AZO/ZnO/PTB7:PC71BM/MoO3/Ag organic solar cell, plasmonic gold nanoflowers were embedded inside the active layer. The critical parameter of thickness of electron transport layer (ETL), hole transport layer (HTL) and active layer war first optimized through simulations using general purpose photovoltaic device model (GPVDM) software. The experimental fabrication of the desired geometry was then carried out based on optimized thickness. The power conversion efficiency (PCE) under UV exposure was found remarkably constant for AZO front electrode solar cell was as compared to conventional ITO based organic solar cells. This is attributed to the UV blocking property of AZO. The PCE was boosted from 6.19% to 7.01% on further use of plasmonic Au nanoparticles in the active layer of AZO/ZnO/PTB7:PC71BM/MoO3/Ag. This work provides a practical insight of developing an ITO free, plasmonic nanoparticles assisted inverted organic solar cell with enhanced efficiency and stability.

Structural and antibacterial properties of doped zinc oxide and their composites with hydroxyapatite

ZnO nanoparticles (NPs) doped by Mn2+ and Cu2+ ions at various doping levels and their hydroxyapatite (HA) composites are prepared by a facile hydrothermal and sol-gel method. The resultant doped ZnO NPs are of wurtzite crystal structure and nanorod morphology. The doping of transition metals in ZnO lattice structure offers feasible means to prepare effective antibacterial agent. The antibacterial property against gram-negative bacteria (E. coli) and gram-positive bacteria (S. aureus) shows that both Mn and Cu-doped ZnO NPs are more sensitive to S. aureus and revealed improved antimicrobial activity relative to pristine ZnO. 5% Mn and 10% Cu-doped ZnO NPs exhibited the best antibacterial property. Moreover, the composites by loading 10 wt% Mn-doped ZnO and 10 wt% Cu-doped ZnO on HA exhibit significant antibacterial activity. The CCK-8 experiments show that ZnO/HA composites are noncytotoxic and can promote osteosarcoma cell growth.

Advanced bio-nanoscaffold for bone tissue regeneration in animal model

Bone tissue engineering is one of the fascinating areas in the field of tissue engineering that aims to develop new strategies for repair of defects in bones using state of the art technologies. New strategies for bone tissue regeneration such as scaffolding are highly encouraged and researched worldwide. The aim of this study was to construct novel scaffolds for regeneration of bone tissue. A base scaffold was synthesized with polyacrylonitrile (PAN) using electrospinning technique. This scaffold was coated with chitosan and then calcium doped zinc oxide nanocrystals were grown on its surface using hydrothermal treatment. The calcium was doped to the nanocrystals to give rise to osteoinductive property. The shape and size of the prepared scaffold was revealed by FE-SEM analysis and it was found to be rod-shaped nanocrystals with size around 218 nm. The XRD pattern and FTIR spectrum indicated the presence of ZnO. The biological characterization of the scaffolds showed superior protein adsorption, biodegradability, bioresorbability and biomineralization properties. In vitro cytotoxicity assessments indicate slight to mild toxicity of scaffolds to L929 and Saos-2 cells. The bone defect filling study using wistar rat indicate complete healing of bone tissue after 28th day of implantation of Ca-doped ZnO covered PAN-chitosan scaffold.

Structural and optical investigations in undoped and rare-earth doped zinc oxide nanoparticles for photon upconversion based applications

The present work reports comprehensive investigations of the physical properties of undoped and rare-earth (RE3+) doped ZnO based upconversion nanoparticles. X-ray diffraction analysis of these nanoparticles reveals the hexagonal wurtzite structure. The induced-strain value of the RE3+ doped ZnO nanoparticles increased by almost one order of magnitude, and their mean particle size reduced from 36 nm to 17 nm. The scanning electron microscopic images showed that the particles retained the spherical shape in the undoped and doped conditions. The elemental maps confirmed the uniform distribution of the RE3+ dopants. The recorded absorbance spectrum for the doped nanoparticles showed significant absorption in ultraviolet and near infra-red regions owing to the band-band transitions and the deep defect level transitions that are induced due to intrinsic and extrinsic defect states. A detailed analysis of the defect states of these samples is described based on the Urbach energy studies. An intense peak observed at 980 nm suggests the possibility of photon upconversion in the doped nanoparticles. A simplified energy diagram (as depicted below) has demonstrated the multi-photon absorption and possible upconversion mechanisms. The optical absorption spectrum of RE3+ doped ZnO nanocrystals encourages the promising application of these materials in diverse fields, particularly in biomedical and photovoltaic applications.

A comprehensive investigation of structural and optical properties of the spray coated Nd-doped ZnO

We report on the synthesis and characterization of Nd3+ doped Zinc oxide (ZnO) thin films fabricated using the chemical spray pyrolysis technique at 723 K. A comprehensive investigation using a combination of experimental techniques is undertaken to unveil the structural, morphological, compositional, electrical, linear, and nonlinear optical characteristics of the Nd-doped (a higher ionic radius dopant) ZnO thin films. The X-ray diffraction reveals a hexagonal wurtzite structure of the polycrystalline deposits with preferred orientation change from (101) to (002) plane at dopant concentrations above 5%. The inclusion of Nd dopants causes the morphology to change from fibrous to needle-like. The oxidation states of the dopant elements were identified by using XPS spectra. The Raman spectroscopy elucidates the deterioration of crystallinity with the increase in the dopant concentrations. The additional absorption band at higher dopant concentrations in the Fourier transform infrared spectra points to a new phase. The optical bandgap and charge carrier concentrations decrease and increase, respectively, with dopant concentrations up to 5 at%, followed by a reversal in the trend at still higher doping. The optical refractive index and extinction coefficient of the doped samples show an increase compared to pure ZnO. The defect-mediated energy transfer from the host ZnO to Nd dopants was identified from photoluminescence spectra. The sign of the third-order nonlinear refractive index changes from negative for pure ZnO to positive with Nd doping.

Effect of sputtering power and substrate temperature on structural, optical, wettability and anti-icing characteristics of aluminium doped zinc oxide

Thin films of ZnO:Al were synthesized on glass substrates by RF magnetron sputtering. Structural, optical, wettability and anti-icing properties of the thin films are studied as a function of substrate temperature and sputtering power. XRD patterns showed an increase in the intensity of (002) peak when the sputtering power and substrate temperature are increased. The roughness and average grain size also increased with an increment in substrate temperature and sputtering power. Transmittance and band gap energy observed in the wavelength range of 350–800 showed the average transmittance was in the range of 90 to 76% and 3.12–2.88 eV. The contact angle and anti-icing properties observed during the investigation demonstrated that the synthesized coatings are hydrophobic and the formation of ice was delayed when compared to uncoated substrates.

Assessing the efficiency of photocatalytic removal of alizarin red using copper doped zinc oxide nanostructures by combining SERS optical detection

Tracking of photocatalytic reaction via surface enhanced Raman spectroscopy (SERS) can facilitate enriched information regarding degradation pathway and kinetics of the reaction. Herein, photocatalytic removal of alizarinred S (ARS) was investigated using a model photocatalytic system like copper doped zinc oxide nanostructures by SERS-assisted optical detection and UV–visible spectroscopic analysis. Zn1-xCuxO (ZCO, x =0–10%) were synthesized using facile co-precipitation method. XRD and Raman studies proved that as-prepared nanoparticles possess a hexagonal wurtzite structure with well intense crystalline peaks even without an annealing process. Structural properties of ZCO nanoparticles were well investigated in terms of optical properties and correlated to photocatalytic activity for decomposing ARS. Photocatalysis studies indicated 92% degradation of ARS within 160 min of light exposure. The degradation profile of ARS using optimum catalyst conditions was investigated by SERS as well. The analysis of fingerprint bands of ARS showed successive deterioration of peak intensities with time. The analysis of the peak at 1477 cm−1 provided a kinetic coefficient of 1.2 × 10−2 min−1 which is concordant with that obtained from UV–visible spectroscopic analysis. Degradation mechanism of as-synthesized ZCO nanoparticles was also well demonstrated. Obviously, complimentary analysis of photocatalytic progression of ARS using SERS was demonstrated; which provided insight into reaction kinetics as well.

Environmental Stability Evaluation of Aluminium Doped Zinc Oxide (AZO) Transparent Electrodes Deposited at Low Temperature for Solar cells

The degradation of transparent electrodes’ electrical conductivity under environmental conditions is considered as a major failure mode for solar cells’ long-term efficiency. In this paper, AZO thin films were subjected to the International Electrotechnical Commission (IEC) 61646 test to examine their environmental stability and suitability as front electrodes for solar cells. To explore the interplay between AZO deposition parameters and environmental stability, AZO films were deposited by radio frequency magnetron sputtering at different parameters and without external heating. The conductivity stability evolution upon the testwas investigated via studying the AZO electrical, structural, and morphological characteristics at different deposition conditions. A direct dependence was identified between the samples’ conductivity degradation rates and the samples’ structural and morphological characteristics including grain size, grain boundary density, surface roughness, and compactness. The samples’ resistivity increases linearly over the test period due to both electron density and mobility degradations. Improved stability was observed for thicker AZO samples (360 nm) originating from enhanced grain size, surface profile, and compactness. These samplesmaintained solar cells' applicable sheet resistance of 21.24 Ω/sq (ρ=7.64×10-4 Ω.cm) following the test. The conducted aging studies demonstrated that manipulating the AZO films growth process via optimizing the deposition parameters is an effective pathway for low-temperature deposited electrodes with enhanced environmental stability

Antibacterial study of ZnO and Zn0.5Mg0.5O nanoparticles synthesized by co-precipitation method

In the present study, zinc oxide (ZnO) and magnesium doped zinc oxide (Zn0.5Mg0.5O) nanoparticles were synthesized by simple and cost-effective co-precipitation method. The synthesized materials were characterized by X-ray Diffraction (XRD), Fourier Transform Infrared (FTIR) spectroscopy, Field Emission Scanning Electron Microscopy (FESEM) with Energy dispersive X-ray spectrum (EDAX). Finally, the effect of magnesium (Mg) doping on the structural, morphological and anti-bacterial property of ZnO nanoparticles was analyzed. From the XRD results, it was found that there was a formation of hexagonal structured ZnO and the average crystallite size of ZnO and Zn0.5Mg0.5O was calculated to be 71 nm and 36 nm respectively. The FTIR analysis confirmed the existence of possible functional groups in ZnO and Zn0.5Mg0.5O. There was formation of almost spherical shaped particles as evident from FESEM images and agglomeration of particles was observed upon doping Mg into ZnO. The EDAX spectra of the prepared nanoparticles provided the composition of Zn, O in ZnO and Zn, Mg, O in Zn0.5Mg0.5O. No other elements have been found in the EDAX spectra of ZnO and Zn0.5Mg0.5O that confirmed the formation of pure materials. Finally the anti-bacterial study demonstrated that ZnO and Zn0.5Mg0.5O was effective in inhibiting E. coli bacteria.

Growth and characterization of transparent vanadium doped zinc oxide thin films by means of a spray pyrolysis process for TCO application

Growth and characterization of transparent vanadium doped zinc oxide thin films by means of a spray pyrolysis process for TCO application

Synthesis and Characterization of Copper Doped Zinc Oxide Thin Films Deposited by RF/DC Sputtering Technique

Synthesis and Characterization of Copper Doped Zinc Oxide Thin Films Deposited by RF/DC Sputtering Technique

Synthesis, characterization, and applications with the manifestation of antifungal activity and seed germination properties of nickel doped zinc oxide nano platform by biochemical contrivance

In the recent era, nanotechnology, a rapidly emerging field, has been explored as the most studied field worldwide. The goal of this study is to use neem leaves extract as an effective ‘reducing agent’ and ‘stabilizing agent’ in the green synthesis of bio-medically important Zn1-XNiXO (X = 0.00, 0.04, 0.08, 0.12) nanoparticles. The molar concentrations of nickel nitrate and zinc nitrate are varied to produce nickel-doped ZnO nanoparticles. Color change is the first indicator of nanoparticle formation during this biosynthesis. The hexagonal wurtzite structure with good crystallinity is confirmed by X-ray diffraction. FTIR analysis reveals the fact that the Zn–O stretching vibration shifts with the introduction of impurities into the ZnO matrix. UV–Vis spectra show the typical surface plasma resonance around 370 nm and the hydrodynamic diameter is larger than the size calculated from the XRD value, according to DLS. The main finding of this study is that Ni0.12Zn0.88O has a strong antifungal activity against and a significant growth rate after treating wheat seeds with biologically synthesized Ni0.12Zn0.88O nanoparticles.