Pure Zinc Oxide Nanoparticles Research Articles

Enhanced catalytic degradation of amoxicillin by phyto-mediated synthesised ZnO NPs and ZnO-rGO hybrid nanocomposite: Assessment of antioxidant activity, adsorption, and thermodynamic analysis

Abstract Antibiotics are resistant compounds that become emerging contaminants that cause hazards to human health and the ecological environment due to their wide production and consumption. The present research reveals the remediation of amoxicillin (AMX) antibiotic by catalytic degradation using fabricated zinc oxide (ZnO) and zinc oxide-reduced graphene oxide (ZnO-rGO) catalysts. The characterization of the catalyst was carried out via UV–Vis spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, energy dispersive X-ray spectroscopy, and scanning electron microscopy to evaluate the morphology and composition of synthesised catalyst. The catalytic ability of ZnO-rGO and ZnO was investigated by analysing the degradation of AMX. The ZnO-rGO nanocomposites (NCs) showed improved catalytic performance towards AMX degradation (96%) than pure ZnO nanoparticles (85%), which may be attributed to the incorporation of rGO, which enhanced the adsorption rate and changed the electron–hole recombination rate. The antioxidant potential of synthesised nanomaterials was also analysed by three different methods. The adsorption behaviour was explained through the Langmuir and Freundlich models, and the results revealed that AMX adsorption followed the Freundlich model more closely for both catalysts. The adsorption of AMX was also studied thermodynamically at different temperatures. The negative Gibbs energy change, positive enthalpy change, and entropy change showed the reaction’s spontaneity and endothermic nature. Finally, it can be assumed that the ZnO-rGO NCs could be an effective semiconductor for the degradation of AMX from wastewater.

Structural, electrostatic force microscopy, work function, and optical characterization of pure and Al-doped ZnO nanoparticles

The electrical and optical characteristics of pure and Al-doped zinc oxide (ZnO) nanoparticles were analyzed. The work function of these nanoparticles was investigated using Kelvin Probe Force Microscopy (KPFM). The work function of the Al-doped ZnO nanoparticles was found to be lower than that of undoped ZnO nanoparticles. Electrostatic Force Microscopy (EFM) was employed to map the distribution of charges and conductivity in both ZnO and Al -doped ZnO, revealing enhanced charge trapping and increased conductivity in the Al-doped ZnO nanoparticles compared to the undoped ones. XRD analysis verified that both pure ZnO and Al-doped ZnO nanoparticles exhibited a hexagonal wurtzite crystal structure. Additionally, Raman spectroscopy revealed new vibrational modes at 572 cm−1, which were attributed to E1 (LO) in Al-doped ZnO. UV–visible spectroscopy indicated that the band gap of Al -doped ZnO nanoparticles is wider than that of pure ZnO nanoparticles, Additionally, photoluminescence spectroscopy demonstrated a blue shift in the emission spectrum of the Al-doped ZnO nanoparticles, accompanied by a reduction in green emission defects.

Investigation of Ethanol gas sensing properties of pristine and Al doped ZnO nanoparticles synthesized by Sol-gel method

Pure and Aluminum-doped Zinc Oxide nanoparticles were prepared by using a simple Sol–gel method. Al contents were varied with 1 wt% and 3 wt% at a fixed concentration of pure ZnO. Synthesized samples were calcinated at 400 °C for 2 h. The results of x-ray diffraction (XRD) confirm that the synthesized nanoparticles have a Hexagonal Wurtzite structure. The average crystallite size of the nanoparticles shows variation from 16 nm to 21 nm. Grain size and surface morphology were investigated with the help of a Field Emission Scanning Electron Microscope (FESEM). Functional groups present in the prepared samples were analyzed by using Fourier Transform Infra-red spectroscopy (FTIR). The percentage response of the fabricated sensor, containing Al-doped ZnO nanoparticles, was examined with exposure to the toxic gas Ethanol. It was observed that percentage response changes due to various sensing parameters like response time and percentage response which, were calculated at 100 ppm and 200 ppm concentrations of toxic Ethanol gas. It was found that with an increase in Al concentration as well as Ethanol ppm level the percentage response of synthesized samples is increased. The maximum percentage response of 17.82 and 20.91 at 100 and 200 ppm with 3 wt% of Al-doped ZnO nanoparticles was observed respectively, which is greater than that of pure ZnO. Also, the same sample shows the lowest response time of 215 s and 120 s at 100 ppm and 200 ppm, respectively. Thus, aluminum doping enhanced the gas sensing response of pristine zinc oxide nanoparticles.

Enhancing dielectric properties of ZnO nanopowders with 2D hBN doping: production, structural, morphological and dielectric characterization

In this study, it was aimed to improve the dielectric properties of ZnO nanoparticles with the addition of hBN, which was not previously available in the literature, and thus to expand their usage areas. Sol–gel synthesis method was used in this study to create pure and hexagonal boron nitride (hBN) doped zinc oxide (ZnO) nanoparticles. Zinc acetate dihydrate Zn(CH3COO)22H2O), sodium hydroxide NaOH, and hexagonal boron nitride (hBN), all from Sigma Aldrich, were used as starting reagents. The reagents were dissolved during the sol–gel synthesis by being heated to 90 °C for 4 h in a magnetic stirrer. FT-IR, XRD, FE-SEM, EDX characterization techniques, and impedance analyzer were used to find functional groups, structural, morphological, and chemical composition, and dielectric properties of the nanoparticles, respectively. The produced un-doped and hBN-doped ZnO particles consist of nano-sized structures. Changes occurred in the intensities and locations of the XRD diffraction peaks and FT-IR peaks with the addition of hBN. Characteristic peaks of both ZnO and hBN were observed in the diffraction peaks of the doped nanoparticles. All nanoparticles were of high purity and were successfully produced by the sol–gel method. It was shown that as the hBN doping level increased, there were more hBN nanoplates in the ZnO matrix, and the EDX results also showed an increase in hBN addition. The frequency stability of the dielectric properties improved after hBN doping. While the dielectric constant at 1 kHz frequency at room temperature is 12.07 in pure ZnO nanoparticles, the increase up to 55.21 is observed in 10% hBN doped nanocomposites. This situation is considered as a great potential for technological applications of this novel nanocomposite material.

Visible‐Light‐Active Electrospun Membranes Based on Cobalt‐Doped ZnO Nanohybrids: Applications for Food Packaging

AbstractA cellulose acetate electrospun membrane based on Cobalt doped ZnO (Co‐ZnO) was developed. The synthesis of pure zinc oxide nanoparticles (NPs) and cobalt‐zinc oxide nanorods with varying cobalt‐to‐zinc atomic ratios of 5 %, 10 %, 15 %, and 20 % was carried out, using the co‐precipitation method. The successful incorporation of cobalt into ZnO was confirmed by using the techniques of Powder X‐ray Diffraction (PXRD), X‐ray Photoelectron Spectroscopy (XPS), and Energy Dispersive X‐ray Spectroscopy (EDX). Scanning Electron Microscopy (SEM) studies denoted the change in shape from spherical to rod‐shaped upon doping Co. A red shift was observed in band gap energies from 3.26‐3.01 eV upon increasing the Co concentration. The photocatalytic activity was evaluated, using methylene blue under sunlight and a 50 W LED lamp. The most effective photocatalyst observed in this study was a composition consisting of 15 % Co‐ZnO. When exposed to sunshine, this photocatalyst demonstrated a degradation rate of 40 % over a one‐hour period. Similarly, when subjected to a lamp, the degradation rate was found to be 24 % over the same duration. A nanofiber membrane was produced by incorporating Co‐ZnO at a concentration of 15 % (w/w) into the cellulose acetate (CA) polymer matrix by the electrospinning technique. The created CA nanofiber mat with Co‐ZnO was employed to extend the shelf life of strawberries up to 18 days along with the reduced pH increase and lower reduction of weight, firmness, and titratable acidity.

Synthesis of Pure and Manganese Doped Zinc Oxide Nanoparticles by a Solution Growth Technique: Structural and Optical Investigation

Pure and manganese doped zinc oxide nanoparticles have been successfully synthesized over the composition range, Zn1-xMnxO (0<x<0.5), by a solution growth process. The effect of Mn doping on the structure, morphology and optical properties were investigated by several techniques. X-Ray diffraction studies confirmed the formation of a single-phase polycrystalline hexagonal wurtzite structure of ZnO within the range, 0 < x < 0.3. No Mn related secondary phases were detected, within this range, which could be attributed to the fact that the dopant atoms had been well incorporated into the ZnO crystal lattice. For Zn1-xMnxO (x = 0.5), several low intensity peaks belonging to remnants of Manganese acetate were observed in the diffractogram, establishing a solubility limit for the synthesis technique used. The variation of d-spacing with Mn percent doping showed a very good agreement with Vergard’s law within the range (0<x<0.25). EDAX analysis of the nanoparticles was consistent with the formation of Mn doped ZnO. The optical band gap of the ZnO nanoparticles decreased linearly with increasing Mn percent doping, suggesting the possibility of tuning the band gap of ZnO by doping with Mn.

Polymer-Assisted Coprecipitation Synthesized Zinc Oxide Nanoparticles and Their Uses for Green Chemical Synthesis via Photocatalytic Glucose Conversions.

Biomass conversions to chemicals via various conventional technologies require high energy consumption, high temperature, high pressure, or high system cost. Alternatively, photocatalysis is one of the greener technologies because it utilizes the energy from lamps or natural sunlight with catalysts to synthesize chemicals under mild conditions and room temperature. In this work, zinc oxide (ZnO) particles were successfully synthesized using polyvinylpyrrolidone as an additive in coprecipitation to control the size and protect the aggregation. The crystal structure of hexagonal wurtzite was found in the obtained nanoparticles. The photocatalytic activities of the obtained samples were evaluated for the production of high-value chemicals (gluconic acid, xylitol, arabinose, and formic acid) via the photocatalytic conversion of glucose under UV-A irradiation. The photocatalytic results indicated the relationship of defects (i.e., oxygen vacancies and zinc vacancies) with glucose conversions. From the ZnO nanoparticles calcined at various temperatures from 400 to 700 °C, the one calcined at 700 °C showed the highest glucose conversion of 21.5% with a high yield of carboxylic acid products (gluconic acid and formic acid). The gluconic acid showed the highest yield of 15% for 180 min, while the formic acid, arabinose, and xylitol presented the highest yields of 7, 1, and 0.5% for 180 min, respectively. Pure ZnO nanoparticles can convert glucose into value-added products without adding an acid or base in the reaction.

Photocatalytic wastewater treatment and disinfection using green ZnO-NP synthesized via cera alba extract

This is the first report to describe the green fabrication of zinc oxide nanoparticles starting with cera alba (beeswax) extract as an eco-friendly reducing and capping agent. The reaction of zinc nitrate with an aqueous extract of Cera Alba resulted in the formation of zinc oxide nanoparticles (ZnO-W). Treatment of ZnO-W at 550 °C gave pure zinc oxide nanoparticles (ZnO-G). Various techniques, including FT-IR, XRD, TGA, SEM, and HR-TEM, were used to analyze the structures of synthesized nanoparticles. A methylene blue dye solution was used to evaluate the photocatalytic activity. The impact of catalyst dose, reaction time, and pH on photocatalytic degradation under sunlight was studied. At optimal conditions, complete photodegradation of 10 ppm methylene blue occurs in 40 min. The antimicrobial activity of ZnO-G was evaluated against three microbial strains: Bacillus cereus, Escherichia coli, and Candida albicans. The impact of exposing the ZnO-G to various light wavelengths (265 nm, 346 nm, visible light, and sunlight) to inhibit microbial growth was investigated. The best result was obtained when ZnO-G was exposed to 265 nm light. This study's findings support using ZnO-G prepared via cera alba as a powerful photocatalytic and antimicrobial agent.

Enhancing antimicrobial and photocatalyst properties of Mg-doped ZnO nanotubes via novel laser-assisted chemical bath synthesis

Laser-Assisted Chemical Bath Synthesis (LACBS) was used to fabricate pure and magnesium-doped zinc oxide nanoparticles. Analysis of these nanoparticles' structural, morphological, optical, and antimicrobial characteristics was conducted. This analysis spanned across varying concentrations of magnesium-doped zinc oxide from 1 % to 3 %. XRD confirmed the nanoparticles' crystalline nature, revealing the hexagonal wurtzite phase. SEM analysis showcased their nanometric domain existence and hexagonal crystalline morphology, transforming from nanorods to nanotubes. Optical analysis showed band gap energy decrease from 3.27 to 2.85 eV correlating with the magnesium doping concentration increase. Optical absorption displayed a distinctive redshift for the nanoparticles as magnesium concentration increased from 1 % to 3 %. Photocatalytic assessments highlighted the superior degradation ability of 3 % Mg-doped nanoparticles, showing a 98.04 % degradation rate against methylene orange dye under blue light exposure. Antimicrobial activity tests against various pathogens showed that Mg ions' incorporation significantly enhanced antimicrobial performance, demonstrating the effectiveness of the LACBS method.

Boosting the photocatalytic activity of ZnO-NPs through the incorporation of C-dot and preparation of nanocomposite materials

Due to their applications in cosmetology, medicine, antibacterial and other fields, zinc oxide nanoparticles (ZnO-NPs) are among the nanoscale materials experiencing exponential growth. In contrast, pure ZnO-NPs have been reported to have a very large energy bandgap, a large exaction binding energy, electron-hole recombination, no visible light absorption, and poor photocatalytic activities, which limit their potential uses. ZnO-NPs can be further extended through the incorporation of trace amounts of carbon materials to engulf these problems. We investigate the photocatalytic degradation of methylene blue (MB) dye with pure ZnO-NPs infused with a limited amount of carbon dot (C-dot) materials. Consequently, adding 10% C-dot to ZnO-NPs reduced their energy bandgap from 3.1 to 2.8 eV and significantly increased their photocatalytic activity. MB was almost completely degraded (98.4%) after 60 min when 50 mg of C-dot-incorporated ZnO-NPs were added. By comparison, the nanocomposite's photocatalytic activity exceeded that of pure ZnO-NPs by more than 50%. A surface charge and stability improvement are responsible for the extraordinary photocatalytic improvement. As far as we know, this is the best-ever photocatalytic improvement achieved by incorporating a trace amount of C-dot material into pure ZnO-NPs.

Biosynthesis of Al-doped ZnO nanoparticles with different Al doping ratio for methylene orange dye degradation activity

Al-doped ZnO nanoparticles were synthesized using the green method for dye degradation activity for the first time. The Allium Calocephalum Wendelbow (ACW) plant leaf extract has been employed in the biosynthesis of the aluminum (Al) doped and undoped (pure) zinc oxide (ZnO) nanoparticles (NPs) for the applicability of dye degradation capability. In order to investigate the dye degradation behavior process, methylene orange (MO) is being used. For produced Al-doped and undoped ZnO NPs, the efficiency and sustainability of the (ACW) leaf plant for the dye decomposition process has been examined. The produced Al-doped and pure ZnO NPs have been studied for their quality and structure using a variety of characterization technique. For the first time, the green synthesis process was applied in order to thoroughly examine the impact of the various Al-doped green ZnO nanoparticle ratios on the average size, shape, distribution, crystal structure, functional group, optical capabilities, chemical compositions, and energy band-gap. The ratio of Al-doped ZnO NPs consisted of 0% (pure), 0.025%, 0.050%, 0.075%, 0.10%, and 0.20%. The results demonstrate that the characteristics of the doped and pure green ZnO NPs are significantly affected by the varied Al-doped ZnO ratio. ACW plant leaf extract was examined using FTIR and UV–Visible spectroscopy, and the results suggested that this extract might be a promising alternative for the environmentally friendly synthesizing of both doped and undoped ZnO NPs. At ambient temperature, the UV–Visible spectra of leaf extract displayed two separate absorption peaks roughly at 262 nm and 350 nm. As additional proof of the ACW plant's use of the green method in this research, the examination of the MO dye degrading activity by Al-doped and pure ZnO NPs was conducted utilizing the newly produced Al-doped and pure ZnO NPs made to utilize the green technology. The Al-doped ZnO NPs produced at a ratio of 0.075% displayed a significant degradation rate percentage when dye degradation ability was measured with UV light. Also, the average dye degradation percentage of 90.5% for 80 min of the fabricated Al-doped green ZnO NPs displayed a quicker than average dye degradation percentage of 74% for 140 min of the fabricated pure green ZnO NPs.

Impact on The Structural, Morphological Properties, and Band Gap Tuning on Zinc Oxide Nanoparticles Substituted By Aluminum

In the present study, we report the effect of Aluminum (Al) doping on the properties of zinc oxide (ZnO) nanoparticles. The sol-gel method was used to synthesize the pure and Al-doped ZnO nanoparticles. Al doping was done at three different concentrations 3%, 5%, and 7%. The presence of Al, Zn, and O is confirmed by EDX and XPS. The crystal structure and morphologic analysis of prepared nanoparticles using XRD, FESEM, and TEM-SAED techniques. An increase in the doping concentration has reduced the average crystallite size considerably in the range of 18–14 nm. The optical properties have been studied using UV–Vis spectrophotometer. The UV–Vis spectroscopic studies showed that Al was incorporated into the ZnO lattice as Al3+ due to the decreasing optical band gap of nanoparticles. The XPS and EDX analysis is done to confirm the elemental composition of the pure and Al-doped ZnO nanoparticles. The addition of a suitable doping agent will lead to the improvement of structural as well as optical properties. The variation in different properties due to the addition of Alas a dopant is also studied.

Effect of green synthesized zinc oxide nanoadditives and rice bran oil biodiesel blend on performance and combustion characteristics of a variable compression ratio diesel engine: an experimental study

AbstractThe aim of this research was to investigate experimentally the performance and combustion characteristics of a four‐stroke, single‐cylinder, water‐cooled variable compression ratio diesel engine using rice bran oil biodiesel blends with zinc oxide nanoparticles. Rice bran oil biodiesel was prepared using a transesterification reaction with a 6:1 methanol‐oil molar ratio and 1% w/w potassium hydroxide as catalyst. Zinc oxide nanoparticles were synthesized using a green method incorporating Psidium guajava leaf extract as a capping agent to reduce precursor use and to reduce the toxicity of the nanomaterial. The synthesized zinc oxide nanoparticles were characterized by using X‐ray diffraction and Fourier‐transform infrared spectroscopy to confirm the formation of highly crystalline pure zinc oxide nanoparticles with a hexagonal wurtzite crystal structure with an average diameter of 20.963 nm. Rice bran‐oil biodiesel‐diesel blend was prepared by volumetrically mixing 20% biodiesel and 80% mineral diesel and was considered as a base fuel for comparison. Zinc oxide nanoparticles were diffused in the base fuel at dosage levels of 25, 50, and 75 ppm, with the aid of ultrasonication. Measurement of the major physicochemical properties of test fuels showed an increase in the cetane number and calorific value and a reduction in viscosity with an increase in the zinc oxide concentration. The overall properties of all the test fuels were found to be similar in comparison with commercial diesel. An experimental engine test was carried out under different loading conditions with a constant speed of 1500 RPM and two different compression ratios – that is, 17.5:1 and 15:1. Among all the test fuels at both compression ratios, engine performance and combustion properties improved with an increase in the zinc oxide concentration. Test fuel with 75 ppm of zinc oxide additive at 17.5 compression ratio resulted in an overall improvement at full load: brake thermal efficiency increased by 2.45%, brake specific fuel consumption reduced by 5.45%, cylinder peak pressure increased by 3.27% and net heat release increased by 10.32% in comparison with base fuel.

Novel Laser-Assisted Chemical Bath Synthesis of Pure and Silver-Doped Zinc Oxide Nanoparticles with Improved Antimicrobial and Photocatalytic Properties

Antimicrobial resistance poses a significant threat to global health, amplified by factors such as water scarcity and suboptimal hygienic practices. Addressing AMR effectively necessitates a comprehensive strategy encompassing enhanced access to potable water, developing innovative antibiotics, and exploring alternative treatment modalities, such as harnessing solar photocatalysis with zinc oxide nanoparticles for water purification and antimicrobial applications. The Laser-Assisted Chemical Bath Synthesis (LACBS) technique facilitates the fabrication of pure ZnO nanostructures, providing a potentially efficacious solution for mitigating pathogen proliferation and managing wastewater. The photocatalytic degradation of MB and MO dyes was investigated using blue laser light at 445 nm, and degradation rates were determined accordingly. Ag-doped ZnO nanostructures were characterized through X-ray diffraction, field emission scanning electron microscopy, energy dispersive X-ray spectroscopy, and Fourier-transform infrared spectroscopy. The antimicrobial efficacy of LACBS-synthesized ZnO nanoparticles was assessed against C. albicans, S. aureus, B. subtilis, E. coli, and K. pneumoniae using the disc diffusion method, revealing 40 mm, 37 mm, 21 mm, 27 mm, and 45 mm inhibition zones at the highest concentration of doped-Ag (4.5%), respectively. These inhibition zones were measured in accordance with the guidelines established by the Clinical and Laboratory Standards Institute. X-ray diffraction patterns for ZnO, ZnOAg(1.5%), ZnO:Ag(3%), and ZnO:Ag(4.5%) samples revealed variations in intensity and crystallinity. Scanning electron microscopy exposed morphological disparities among the nanostructures, while energy-dispersive X-ray spectroscopy verified their elemental compositions. UV-Vis absorption analyses inspected the optical band gaps, and Fourier-transform infrared spectra identified the stretching mode of metal-oxygen bonds. Under blue laser irradiation, Ag-doped ZnO exhibited enhanced photocatalytic activity during the photocatalytic degradation. These nanoparticles, synthesized via the cost-effective and straightforward LACBS method, benefit from silver doping that augments their electron-trapping properties and photocatalytic activity, thereby enabling efficient dye degradation. Consequently, Ag-doped ZnO nanoparticles hold promise as a potent solution for counteracting drug-resistant microorganisms and as an effective disinfectant.

Dye-sensitized solar cells fabricated using ZnO:Cu thin films and dye extracted from Hypericum perforatum L. flowers

Dye-sensitized solar cells (DSSC) were designed utilizing pure and copper-doped zinc oxide (ZnO:Cu) nanoparticles and the dye extracted from dried Hypericum perforatum L. (H. perforatum) flowers. The ZnO:Cu thin films were grown using the successive ionic layer adsorption and reaction (SILAR) method on tin-doped indium oxide-coated (ITO) glass substrates at 85 °C. Regarding the molar ratio of Cu ions to Zn ions, Cu had a doping concentration of 0.5%, 1%, and 2%. The crystalline nature, morphological, compositional, and optical properties of the synthesized ZnO:Cu thin films were studied using an X-ray diffractometer (XRD), a scanning electron microscope (SEM), energy dispersive x-ray spectrometry (EDS), UV-vis spectroscopy, and Fourier transformation infrared (FTIR) spectroscopy. The SEM results indicated the formation of a porous structure on the surface of ZnO:Cu thin films, which provided more active sites for dye molecules and electrolyte ions. A DSSC, produced by using a pure ZnO thin film, showed a current density (Jsc) of 7.66 mA/cm2 with an open-circuit voltage (Voc) of 0.98 V and an overall efficiency (η) of 2.47%

Characterization of green synthesized of ZnO nanoparticles by using pinus brutia leaves extracts

Zinc oxide (ZnO) nanoparticles have been synthesized by the leaf extracts of the Pinus Brutia (PB) Tree. The impact of the Pinus Brutia (PB) tree extracts and several pH values of the green fabrication mixture (6 to 12) on the ZnO NPs' characteristics has been investigated using several characterization techniques. The obtained results of both analysis of FTIR and UV–Visible spectroscopies of the acquired chosen plant, PB, were demonstrated and proposed to be a better option for the GS ZnO NPs at various pH levels. The UV–Visible spectrum of PB tree leaf extracts displayed one strong absorption peak at 275.3 nm at ambient temperature. The obtained FESEM results analysis demonstrated that the pH values have a noticeable and huge impact affecting the morphology, orientation, shape, and dimensions of the Green Synthesized (GS) ZnO NPs, which are spherical in form and range in size from (37.47 to 73.70 nm). Additionally, the XRD data demonstrate that the produced GS ZnO NPs are GS ZnO that has hexagonal and wurtzite crystal structure, having particle sizes along the (002) peak within the (16.9–24.15) nm range. The UV–Visible analysis of the synthetic GS ZnO NPs revealed a significant peak for ZnO NPs made at various pH levels; the absorption is high in the UV area of less than (400 nm), and with a low absorption rate in the visible range. The band-gap energy (Eg) measured is in the (2.6–2.724) eV range. Additionally, the FTIR analysis of GS ZnO nanoparticles at various pH levels revealed no apparent peak throughout the visible range, demonstrating pure GS ZnO nanoparticles produced by employing PB tree leaf extracts. According to the results of the GS ZnO NP investigations, the GS ZnO NPs produced at pH 8 showed good quality and good improvement in comparison to the ZnO NPs produced at other pH values,

Enhanced detection of low concentration volatile organic compounds using advanced doped zinc oxide sensors.

Pure zinc oxide nanoparticles, as well as those doped with 3% calcium, aluminum, and gallium, were synthesized using a sol-gel method and then deposited onto an alumina substrate for sensing tests. The resulting nanoparticles were characterized using a variety of techniques, including X-ray diffraction (XRD), scanning electron microscopy (SEM) equipped with energy dispersive X-ray analysis (EDX), transmission electron microscopy (TEM), UV-VIS-NIR absorption spectroscopy, and photoluminescence (PL) measurements, to examine their structural, morphological, and optical properties. The prepared nanoparticles were found to have the hexagonal wurtzite structure of ZnO with a P63mC space group. The UV-Vis-IR spectra showed that the samples are highly absorbent in the UV range, while the PL spectra confirmed the presence of many defects in the ZnO structure, such as oxygen vacancies and zinc interstitials. The doped samples exhibited more defects than the pure sample. SEM images of the deposited film surface showed agglomerates with a spherical shape and confirmed the nanometer scale size of our prepared samples, as corroborated by the TEM images. The EDX spectra indicated the high purity of the ZnO deposited films, with a high presence of Zn and O and the presence of the doped elements (Ca, Al, and Ga) in each doped sample. Sensing tests were performed on ZnO, Ca3%-doped ZnO (C3ZO), Al3%-doped ZnO (A3ZO), and Ga3%-doped ZnO (G3ZO) sensors in the presence of volatile organic compounds (VOCs) gases such as ethanol, formaldehyde, methanol, and acetone at low concentrations. The sensors exhibited high responses to low ppm level concentrations of the VOCs gases. At a low operational temperature of 250 °C, the C3ZO sensor had the highest response to 5 ppm of ethanol, methanol, and formaldehyde gases compared to the pure and other doped sensors. Additionally, the A3ZO sensor exhibited the highest response to acetone gas. In conclusion, our findings suggest that the doping of zinc oxide can enhance the low concentration detection of VOCs gases, with the C3ZO and A3ZO sensors showing the highest response to specific gases.

Photocatalytic Degradation of Methyl Green Dye Mediated by Pure and Mn-Doped Zinc Oxide Nanoparticles under Solar Light Irradiation

Herein this study, pure and manganese- (Mn-) doped ZnO (2 wt. %) nanoparticles have been synthesized using the chemical precipitation method and characterized for the photodegradation of methyl green (MG) pollutant dye under natural sunlight. The structural analysis via XRD patterns has revealed that both intrinsic and Mn-doped ZnO (2 wt. %) samples have hexagonal wurtzite structures with appropriate phase purity, clearly indicating the absence of any external impurity. The incorporation of Mn in the host ZnO lattice has decreased the crystallite size (21.10 → 18.76 nm), and nanoparticle-type surface features with sizes in the 50–100 nm range have been observed through FESEM-based surface morphological studies. Both aforementioned observations have merit in providing more active area and a high surface area to volume ratio for photocatalytic reaction. The investigation of photophysical properties indicates that in Mn-doped ZnO nanoparticles, the absorption peak is blue-shifted by 5 nm (365 → 360 nm), due to the widening of the bandgap. The degradation kinetics of MG dye follow the pseudo-second-order kinetics, and the degradation efficiency has been observed to be 62.78% mediated by pure ZnO and 66.44% by Mn-doped ZnO (2 wt. %) photocatalyst under 60 minutes of sunlight irradiation. Specifically, the rate of photocatalytic reaction (K) ~0.01792 min-1 and [Formula: see text]~0.97992 has been achieved for pure ZnO, whereas slightly higher (K) ~0.02072 min-1 and [Formula: see text]~0.97299 have been observed for Mn-doped ZnO, respectively. Conclusively, the synergistic interactions with multiple charge transfer pathways, improvement of e−/h+ pair charge separation, improved surface area, and efficient generation of hydroxyl radicals are supposed to be responsible for the highly efficient photocatalytic activity of the Mn–doped ZnO photocatalyst for MG dye.

Effect of La3+ and Ce3+ dopant ions on structural, optical, magnetic, and antibacterial activity of ZnO nanoparticles

In the present study, pure and co-doped zinc oxide (ZnO) nanoparticles (Zn 1−2 x La x Ce x O) with atomic percentages x = 0, 0.5, 1.5, 2.5, and 3.5 at% were synthesized via the chemical co-precipitation method. The impact of lanthanum and cerium dopant ions (La 3+ and Ce 3+ ions, respectively) on the structural, morphological, optical, magnetic, and antibacterial activity of the ZnO nanoparticles was investigated. X-ray diffraction patterns reveal the wurtzite hexagonal crystal structure of ZnO nanoparticles (NPs) with the formation of two secondary phases (CeO 2 and La 2 O 3 ) when x =1.5 and 2.5 at% or higher, respectively. La 3+ and Ce 3+ ions show a high impact on the morphology of ZnO NPs, as revealed by transmission electron microscopy analysis. Fourier transform infrared spectroscopy results indicate that La 3+ and Ce 3+ ions induce a red shift in the zinc–oxygen (Zn–O) vibrational mode. The incorporation of La 3+ and Ce 3+ ions into the ZnO matrix showed a remarkable impact on the ZnO NP optical properties. At room temperature, the M–H magnetic hysteresis of the synthesized samples reveal a combination of both diamagnetic and ferromagnetic contributions. The antibacterial properties of the synthesized NPs were also evaluated against six bacterial strains using the agar well diffusion method. The synthesized NPs suppressed the growth of the investigated bacteria with various degrees of toxicity.

Green Hydrothermal Synthesis of Zinc Oxide Nanoparticles for UV-Light-Induced Photocatalytic Degradation of Ciprofloxacin Antibiotic in an Aqueous Environment

The design and development of new cost-effective, clean, and efficient synthesis procedures for the synthesis of nanoparticles have recently become an intriguing research topic with broad implications. This study aimed to develop an eco-friendly biogenic method that uses minimum nontoxic chemicals to yield ZnO nanoparticles with enhanced capabilities for degradation of pharmaceutical by-products. The present study used black dried lemon peel aqueous extract as a biological stabilizing agent to prepare pure and stable zinc oxide nanoparticles (LP-ZnO NPs). The surface morphology, elemental composition, crystalline properties, size, optical properties, the role of functional groups in stabilization, capping, and the thermal stability of LP-ZnO NPs were investigated using scanning electron microscopy equipped with energy dispersive X-ray (SEM-EDX), X-ray diffraction (XRD), UV–visible diffuse reflectance spectroscopy (UV-DRS), PL, Fourier transform infrared (FTIR), Raman spectra, and thermogravimetric (TGA) analyses. Multiphoton resonances were observed in LP-ZnO NPs along the crystalline structure as per Raman analysis. The developed LP-ZnO NPs were thermally stable at an annealing temperature of 500 °C with a weight loss of 53%. Photodegradation of antibiotic ciprofloxacin was observed in the presence of UV light via LP-ZnO NPs (serving as photocatalyst). In addition, in optimal reaction media, the biogenic LP-ZnO NPs retained improved photocatalytic performance toward ciprofloxacin. Meanwhile, in the photodegradation process of CPI molecules via ZnO as a photocatalyst, the optimum catalytic dose, concentration of CIP molecules, and pH were attained at 10 mg, 2 × 10−5 M, and pH 8, respectively. The aim of this research work was to develop a simple, affordable photocatalytic technique for the photodegradation of antibiotics in aqueous media. The photocatalytic process was performed under different experimental conditions, including varying catalytic doses, ciprofloxacin concentrations, and pH of the reaction mixture.