Structure Of ZnO Research Articles

Modulation of optical and photoluminescence properties of ZnO thin films by Mg dopant

Nanostructured Zn1−xMgxO (x = 0–0.04) thin films were deposited on a glass substrate through the sol–gel dip coating. X-ray diffraction indicates the films exhibited a hexagonal wurtzite structure with maximum intensity at (1 0 1) plane. The intensity of the diffraction peak decreased with increasing the Mg doping concentration. The crystallite size varied as a function of the increase in Mg doping concentration. The deposits showed a nanograin structure for pure ZnO, which changes in the presence of Mg content, and elemental composition was confirmed by using energy-dispersive spectra. Optical analysis showed a significant increase in transmittance from 80 to 90% in the visible range and a decrement in the optical bandgap energy from 3.305 to 3.261 eV with an increase in Mg doping. Photoluminescence spectra showed there was a quenching of near band edge emission with doping concentration and a red emission for Zn0.96Mg0.04O film. The color coordinates of the deposits were in the nearly white light region, showing the maximal white light emission.

Boosting the Antibacterial Performance of Natural Rubber Latex Foam by Introducing Silver-Doped Zinc Oxide.

Natural rubber (NR) latex foam is one of the rubber products that are increasingly in demand in the market. This is simply because of its lightweight, good thermal insulation, and resilience. The applications of NR latex foam are mostly for pillows and mattresses. This has resulted in these products requiring antibacterial performance which is very important for the safety of the end-users. In this study, the antibacterial NR latex foam was prepared by incorporating the silver-doped zinc oxide (Ag-doped ZnO) into the NR latex foam. Ag-doped ZnO was prepared by microwave-assisted method and then characterized through morphological characteristics and X-ray diffraction (XRD). The content of Ag doped onto ZnO was designed by varying the AgNO3 content at 15 wt%, 50 wt%, and 100 wt% of ZnO. The results confirmed that the Ag was successfully doped onto ZnO. The silver particles were found to be in the 40-50 nm range, where the size of ZnO ranges between 300 and 400 nm, and the Ag attached to the ZnO particles. The XRD patterns of Ag-doped ZnO correspond to planes of hexagonal wurtzite ZnO structure and cubic metallic Ag. This Ag-doped ZnO was further added to NR latex foam. It was observed that Ag-doped ZnO did not affect the physical properties of the NR latex foam. However, it is clear that both the inhibition zone and percent reduction of bacteria (e.g., E. coli and S. aureus) were enhanced by the addition of Ag-doped ZnO. It showed a decrease in the amount of cell growth over contact time. The content of 100 wt% AgNO3 could reduce E. coli and S. aureus up to 64.72% and 58.90%, respectively, when samples were maintained for 24 h. This study provides a scientific understanding of how Ag-doped ZnO could facilitate the development of eventual rubber foam products based on the respective results.

NiFe2O4/ZnO nanocomposites for degradation of MB dye with their local electrical behavior

In the present work NiFe2O4/ZnO nanocomposites were successfully prepared by in-situ wet chemical co-precipitation process. XRD study reveals the presence of the cubic structure of NiFe2O4 and wurtzite hexagonal structure of ZnO. FTIR reveals the distribution of cations and anions at different interstitials sites. Further, the morphology of synthesized sample is analyzed by use of TEM. The oxidation state was explained from X-ray photoelectron spectroscopy (XPS). Dielectric constant is calculated from impedance spectroscopy. UV–vis spectroscopy was used to evaluate the band gap (1.68eV-3.2 eV) of the materials by Tauc's plot. As a model contaminant methylene blue (MB) dye used to check the performance and (0.5) NiFe2O4 - (0.5) ZnO sample shows the maximum degradation efficiency which is 91.36%. The photocatalytic activity of composites is found to be better than bare materials.

Physical characterizations and methane gas–sensing of AlxZn1-xO nanoparticles

The effects of the Al ratio on the morphological and structural parameters, thermal stability, surface area, optical band gap, and methane (CH4) gas–sensing of AlxZn1-xO nanoparticles were investigated. The homogeneous precipitation method was used to prepare AlxZn1-xO nanoparticles (x = 0, 0.5, 1, 2, and 4 at.%) and their compositions were revealed by EDX mapping. The hexagonal crystal structure of ZnO was obtained by annealing at 600 °C and wasn’t affected by the Al ratio. The crystallite/particle size was decreased while dislocation density and stacking fault were increased as Al content increased. The Al ratio controls the morphology of AlxZn1-xO e.g., rod-like, and nano-sheet shapes were observed for higher Al ratios. UV–visible absorption spectroscopy was utilized to investigate the optical absorbance and optical band gap (Eg), e.g., increasing the Al content increased Eg from 3.38 eV (for ZnO) up to 5.8 eV for Al0.04Zn0.96O. Al-doped ZnO has a considerable impact on both the surface area and the thermal stability of ZnO. The maximum surface area (189.72 m2/g) was achieved for the Al0.005Zn0.995O. The sensing parameters as a function of operating temperature and Al doping ratio have been thoroughly tested. The Al0.005Zn0.995O revealed the best sensing performance toward CH4 gas.

Ultrasonically synthesized MgZnO nanoparticles for enhanced piezo-photocatalysis and MgZnO/p-Si heterojunction diode characteristics

ABSTRACT Limitations in practical implementations of ZnO nanomaterials could be solved by tuning the properties of ZnO via doping process. We have doped the Mg2+ ions in the ZnO nanostructures (MgZnO) via the ultrasonic synthesis procedure. The structural study revealed the shrinkage of the crystallite size of the wurtzite system for Mg2+ doping concentration. The TEM images revealed the morphological changes for Mg2+ doping from particulate (50 nm) to nanoflower structures (200 nm) in ZnO. Optical studies revealed the enhanced UV photons absorption and emission intensities for Mg doped ZnO compared to pristine ZnO. The calculated bandgap values from the absorption spectroscopy of the ZnO, MgZnO-1, MgZnO-3, and MgZnO-5 are 3.34 eV, 3.40 eV, 3.51 eV, and 3.57 eV. The prepared MgZnO/p-Si heterojunction diodes showed excellent rectification behavior and enhanced electrical properties for Mg2+ doping. The diode obtained with 5% of Mg2+ had exhibited the ideality factor value of 3.1. Pristine ZnO had exhibited only 66% of photocatalytic methylene blue (MB) degradation efficiency. One hundred percent degradation of MB had been achieved via piezo-photocatalytic effect with 5% Mg2+ doped ZnO, whereas piezocatalysis and photocatalysis had shown 82% and 98% respectively.

Investigation of structural, morphological, optical, elemental, and anticancer property of pure ZnO and PbO: ZnO nanocomposites prepared by flame synthesis method

In this work, Pure ZnO nanoparticles and a nanocomposite of PbO: ZnO were prepared by the flame synthesis method, and was analyzed for structural, morphological, optical, elemental, and biocompatibility studies. The structural analysis revealed a hexagonal structure for ZnO and an Orthorhombic structure for PbO: ZnO nanocomposite. Scanning electron microscopy (SEM) image showed a Nano-Sponge-like surface morphology for PbO: ZnO nanocomposite and energy dispersive spectra (EDS) confirmed the absence of undesired impurities. Transmission electron microscopy (TEM) image showed a particle size of ∼50 nm for ZnO and ∼20 nm for PbO: ZnO. Using Tauc plot the optical band gap was found to be 3.2 eV for ZnO and 2.9 eV for PbO: ZnO. Anticancer studies confirm the excellent cytotoxicity activity of both compounds. PbO: ZnO nanocomposite has demonstrated the highest cytotoxicity against the tumorigenic HEK 293 cell line with the lowest IC50 value of 13.04 μM. Our study shows that the prepared PbO: ZnO nanocomposite has a huge potential in cancer therapy.

Preparation and Characterization of ZnO – ZnFe2O4 Nanocomposites

Zinc oxide (ZnO) and zinc ferrite (ZnFe2O4) powders are synthesized using a sol-gel combustion method. The synthesized powders' crystal structure and microstructure are studied using X-ray diffraction (XRD), Fourier transformation spectroscopy (FTIR), and a field effective scanning electron microscopy (FESEM). XRD studies confirm the presence of nanocrystalline hexagonal wurtzite structure for ZnO and spinel phases for ZnFe2O4. The average crystallite size of the powders measured from XRD patterns is 16 nm for ZnO and 10 nm for ZnFe2O4, respectively. The composite samples of (x) ZnO + (1-x) ZnFe2O4 (where 0 ≤ x≤ 1) are prepared by high energy ball milling and sintered at 900°C in a microwave furnace. The prepared composite samples are characterized using X-ray diffraction, UV-visible spectroscopy, and scanning electron microscope (SEM). The grain size of all composite samples ranges from 74 to 132 nm. The room temperature complex permittivity (ɛ' & ε″″) of composite samples is measured in the frequency range of 1 MHz–1.8 GHz.

Green synthesis of carbon-doped zinc oxide using Garcinia mangostana peel extract: Characterization, photocatalytic degradation, and hydrogen peroxide production

Recent decades have cordially observed unprecedented events in the fields of photochemistry for water remediation and fine chemical production. In this study, we reported sustainable methods to fabricate carbon-doped zinc oxides (ZnO–C) using aqueous Garcinia mangostana peel extracts as a carbon source. Via the reinforcement of ZnO–C crystal structures with the employment of calcination techniques, ZnO–C accentuated better crystallization with average nanoparticle size of 25–70 nm. In addition to the introduction of carbon, the samples revealed the doping of heteroatoms such as N, S, and P simultaneously in ZnO structures originating from the phytochemicals in the extracts. It is observed that ZnO–C sample calcinated at 700 °C for 1 h gives out the best results for photoactivity. Moreover, the fabricated ZnO–C-700-1.0 exhibited a near complete removal towards methylene blue and malachite green, while removal of rhodamine B was 62.13% after 120 min using commercial UV light irradiation under pH 11 with the usage of 50 mg of catalyst. Further investigations of H2O2 photoproduction also validated the versatile application of the materials with the highest H2O2 evolution rate reaching 38.75 mM/g.h. The techno-economical of H2O2 production using ZnO–C reveals the scale-up viability of the process. Moreover, MB removal efficiency of 92.13% and H2O2 production of 8.83 mM/g.h were observed for the optimal ZnO–C sample under visible light irradiation. Subsequently, these results reinforce the applicability of phytoextract as a green approach to reach sustainability for synthesis and modifying the optical structure of semiconducting materials for water remediation and H2O2 production.

Electrocatalytic Degradation of Rhodamine B Using Li-Doped ZnO Nanoparticles: Novel Approach.

In this paper, we discuss the preparation of Li-doped ZnO nanostructures through combustion and report on their structural, morphological, optical, and electrocatalysis properties. X-ray diffraction analyses show that the samples have a structure crystallized into the usual hexagonal wurtzite ZnO structure according to the P63mc space group. The scanning electron microscope images conceal all samples' nanosphere bundles and aggregates. The reflectance spectra analysis showed that the direct bandgap values varied from 3.273 eV (for pure ZnO, i.e., ZnL1) to 3.256 eV (for high Li-doped ZnO). The measured capacitance concerning frequency has estimated the variation of dielectric constant, dielectric loss, and AC conductivity against AC electric field frequency. The dielectric constant variations and AC conductivity are analyzed and discussed by well-known models such as Koop's phenomenological theory and Jonscher's law. The Raman spectra have been recorded and examined for the prepared samples. Rhodamine B was electro-catalytically degraded in all prepared samples, with the fastest time for ZnL5 being 3 min.

A controllable cobalt-doping improve electrocatalytic activity of ZnO basal plane for oxygen evolution reaction: A first-principles calculation study

To design highly efficient, low-cost, and good stable electrocatalysts for the oxygen evolution reaction (OER) which is the key to the water-splitting, we doped ZnO with different concentrations of Co based on density functional theory calculations. The precise Co concentrations control from 0 % to 100 % can be achieved by cation exchange reaction in the experiment. The introduction of Co can modulate the electronic structure of ZnO, as the concentration of Co increases, the band gap greatly decreases, the system tunes from the semiconductor to the metal, and the electric conductivity is significantly improved, favoring the OER. The introduction of Co induces charge arrangement, the electrons gradually concentrate on the active site, and the bindings between the oxygen-containing intermediate and the surface are greatly improved, therefore, the potential of the OER decreases, the rate-determining step changes from the first step in pure ZnO to the third step in Co exchanged ZnO. Additionally, Co0.5Zn0.5O exhibits the favorite OER activity with the overpotential of 0.4 V. These interesting findings may simulate experimental validations and facilitate the development of more efficient OER catalysts.

Effect of (Ce, Dy) co-doping on the microstructural, optical and photoluminescence characteristics of solution combustion synthesized ZnO nanoparticles.

Solution combustion synthesized ZnO nanoparticles with Ce, Dy doped and co-doped with varying dopant concentrations were characterized for their microstructural, optical and photoluminescence characteristics. The synthesized nanoparticles have been found to match the standard hexagonal wurtzite structure of ZnO. The lattice fringes in the high-resolution transmission electron micrographs and the bright spotty rings in the selected area electron diffraction pattern authenticate the high crystallinity of the nanoparticles. The diffuse reflectance spectroscopy provides the energy bandgap for the undoped ZnO to be 3.18 eV, decreasing upon doping and co-doping. A sharp narrow UV emission peak at ~ 398 nm originating from the excitonic recombination is found in the PL spectra of the nanoparticles. The visible emission peaks in the PL spectra are assigned to f-d and f-f electron transitions of Ce3+ and Dy3+ ions, respectively, in addition to different native defects in ZnO. The visible emissions (blue, yellow and red) have been found to improve upon (Ce, Dy) co-doping, and therefore (Ce, Dy) co-doped ZnO nanoparticles can be considered as a promising luminescent material for the development of energy-saving light sources.

UV assisted synthesis of folic acid functionalized ZnO–Ag hexagonal nanoprisms for efficient catalytic reduction of Cr+6 and 4-nitrophenol

Chemical-based syntheses of metallic nanoparticles (MNPs) has become a major topic of research exploration in the field of nanotechnology. The utilization of folic acid (FA) as stabilizing and capping agent has been reported as a novel route for the synthesis of bimetallic nanomaterials. The present study includes novel research and brief discussion about preparation of UV light assisted ZnO–Ag nanobars (NBs) using FA as stabilizing agent and its catalytic applications on the reduction of organic pollutants (4-NP and Cr+6) using NBs as a catalyst alongwith ascorbic acid (AA). Analytical techniques including UV–visible spectroscopy, XRD, SEM, EDX and FT-IR were used for the characterizing synthesized ZnO–Ag NBs. Hexagonal structure of ZnO–Ag NBs were found having crystallite size 5.6 nm and SEM studies revealed the nanobar width 33.2 nm and length 133.5 nm. The prepared ZnO–Ag NBs were tested for their catalytic activity for the reduction of 4-nitrophenol (4-NP) and Cr+6. In the presence of ZnO–Ag NBs and AA, an effective reduction of 4-nitrophenol (4-NP) and Cr+6 was achieved up to 93% and 90% in 17 and 26 min with respectively. The successful and efficient catalytic activity of NBs may be attributed to the size of NBs or the concentration of FA employed for synthesis.

UV‐blocking performance and antibacterial activity of Cd, Ba co‐doped ZnO nanomaterials prepared by a facile wet chemical method

The utilization of highly efficient ultraviolet (UV)‐attenuating materials has inevitably signaled an ever‐increasing demand to mitigate the impending pessimistic impact of UV rays that consistently depletes the ozone atmosphere. In this context, a highly efficient Cd, Ba co‐doped ZnO nanomaterial has been prepared using a facile wet chemical approach. X‐ray diffractometer analysis indicates the evolution of wurtzite structure of ZnO with a slight peak shift towards the higher angle upon co‐doping which ascertains the impacted lattice contraction. N2 adsorption/desorption isotherms of the material supplement magnificently a typical type‐IV behavior displaying an H1 type hysteresis loop at high pressures whereby authorizing the open meso‐porous characteristics. The resulting Cd, Ba co‐doped ZnO nanorods disclose integrated performances of widespread polychromatic UV–visible luminescent emission, wide band gap, and enhanced UV absorbance. In particular, Cd, Ba co‐doped ZnO nanorods impart a positive UV‐blocking execution of 97% for UVA at 360 nm and 88% for UVB at 320 nm, which is found to be higher than most of the reported ZnO‐related materials. Besides these intriguing aforementioned properties, co‐doping is also appropriate for imparting better bacterial inhibition against the two tested strains (Escherichia coli and Staphylococcus aureus). Altogether, these results indicate that the co‐doped ZnO nanorods developed in the current investigation could potentially serve as a propitious alternative UV‐blocking material, especially for biomedical applications.

Meropenem Incorporated ZnO Nanoflakes as Nano Antibiotics: Efficient Antimicrobial Activity against Metallo β-lactamase Producing Clinical Isolates

The number of fatalities caused by multidrug-resistant (MDR) bacteria is over 700,000 annually due to widespread antibiotic usage. So, there is a need of new antibiotics, materials that work like antibiotics, or combinations of antibiotics with nanomaterials that could help in treating the infections which is caused by MDR bacteria. The present study describes the synthesis of ZnO nanoflakes using a co-precipitation method. The ZnO nanoflakes and ZnO nanoflakes combinations with carbapenem antibiotics were tested against carbapenem-resistant (CR) clinical isolates. The SEM analysis showed surface morphology of the synthesized nanoflakes-like structure of ZnO. All 67 CR isolates were tested and showed inhibitory action at varying concentrations of ZnO nanoflakes. ZnO nanoflakes were found to have an inhibitory effect against Escherichia coli and Klebsiella pneumoniae at lowest concentration of 1.25 mg.ml-1 of ZnO NPs with average zone size (mean ±SD) 1.91±2.94 mm and 2.00±4.14 mm and the average zone size of ZnO nanoflakes against Acinetobacter baumanni and Pseudomonas aeruginosa was 9.89±0.76 mm and 10.17±0.39 mm at 2.5 mg.ml-1 concentration. The combined action of ZnO nanoflakes with Meropenem 10 mcg demonstrated synergetic activity against CR pathogens, with an average zone of inhibition measuring 15.2 mm in diameter. ZnO nanoflakes illustrated considerable antibacterial activity against MBL-producing gram-negative clinical isolates at the lowest concentration. Chemically synthesized ZnO nanoflakes may offer a superior future expectation as a nano-antibiotic to treat the infection caused by CRE bacteria.

Twin-brush ZnO mesocrystal for the piezo-activation of peroxymonosulfate to remove ibuprofen in water: Performance and mechanism

Mesocrystals are highly ordered mesoporous superstructures with rich defects and high internal porosity, which are featured by the anisotropic charge migration in catalysis. In this work, we first used twin-brush hierarchical structures of ZnO (TB-ZnO) as piezoelectric mesocrystal with abundant oxygen vacancies to activate peroxymonosulfate (PMS) under piezoelectric activation. Compared with non-mesocrystal of common ZnO nanorods (NR-ZnO), TB-ZnO exhibited 3.7 times of performance for the ibuprofen (IBP) pollutants degradation in the presence of PMS and ultrasonic vibration, and achieved a high PMS utilization efficiency that exceeds the state-of-the-art catalysts. Experimental and theoretical results revealed that the presence of oxygen vacancies together with order mesoporous superstructures in TB-ZnO promoted the electron transfer, decreased the reaction barriers, and facilitated the mass transfer, thus enabling more electrons to participate in PMS activation. These findings open up an avenue to improving the utilization efficiency of PMS in the piezo-activation system for environmental remediation.

The influence of Sb doping on the local structure and disorder in thermoelectric ZnO:Sb thin films

Thermoelectric transparent ZnO:Sb thin films were deposited by magnetron sputtering, with Sb content varying between 2 and 14 at%. As evidenced by X-ray diffraction analysis, the films crystallize in the ZnO wurtzite structure for lower levels of Sb-doping, developing a degree of amorphization for higher levels of Sb-doping. Temperature-dependent (10–300 K) X-ray absorption spectroscopy studies of the produced thin films were performed at the Zn and Sb K-edges to shed light on the influence of Sb doping on the local atomic structure and disorder in the ZnO:Sb thin films. The analysis of the Zn K-edge EXAFS spectra by the reverse Monte Carlo method allowed to extract detailed and accurate structural information in terms of the radial and bond angle distribution functions. The obtained results suggest that the introduction of antimony to the ZnO matrix promotes static disorder, which leads to partial amorphization with very small crystallites (∼3 nm) for large (12–14 at%) Sb content. Rutherford backscattering spectrometry (RBS) experiments enabled the determination of the in-depth atomic composition profiles of the films. The film composition at the surfaces determined by X-ray photoelectron spectroscopy (XPS) matches that of the bulk determined by RBS, except for higher Sb-doping in ZnO films, where the concentration of oxygen determined by XPS is smaller near the surface, possibly due to the formation of oxygen vacancies that lead to an increase in electrical conductivity. Traces of Sb–Sb metal bonds were found by XPS for the sample with the highest level of Sb-doping. Time-of-flight secondary ion mass spectrometry obtained an Sb/Zn ratio that follows that of the film bulk determined by RBS, although Sb is not always homogeneous, with samples with smaller Sb content (2 and 4 at% of Sb) showing a larger Sb content closer to the film/substrate interface. From the optical transmittance and reflectance curves, it was determined that the films with the lower amount of Sb doping have larger optical band-gaps, in the range of 2.9–3.2 eV, while the partially amorphous films with higher Sb content have smaller band-gaps in the range of 1.6–2.1 eV. Albeit the short-range crystalline order (∼3 nm), the film with 12 at% of Sb has the highest absolute Seebeck coefficient (∼56 μV/K) and a corresponding thermoelectric power factor of ∼0.2 μW·K−2·m−1.

Nanostructured ZnO as an efficient heterogeneous photocatalyst towards degradation of lignin under visible light irradiation

The heterogeneously catalysed oxidation of alkaline lignin over 2D nanosheets of ZnO photocatalyst is being reported. A comparative investigation between ZnO bulk and nanostrucutred form towards catalytic performance has also been presented. The XRD and HR TEM patterns revealed the wurzite phase of the ZnO nanostructure. FESEM images showed the layered structure of ZnO having dimensions ∼ 30 nm. Raman data supported the wurzite phase along with presence of considerable defects in ZnO NS. A broad photoluminiscence pattern between 350 and 700 nm, and well-structured bands at 400, 420 and 470 nm indicated the blue emissive nature of ZnO NS. Photochemical oxidation of alkaline lignin, is investigated by varying reaction conditions to achieve a maximum of 93% lignin degradation within 2 h, at a pH of 9. ZnO NS having smaller particle size, better exposed surface area, defects within, showed better catalytic activity compared to bulk ZnO. The 2D nanosheets offer effective adsorption of lignin onto the internal surface, while defects within ZnO NS favor generation and stabilization of hydroxyl radicals. These radicals attack the lignin units, eventually leading to oxidative degradation of lignin. Non-significant leaching of zinc ions into the reaction during the studies, demonstrates the heterogeneous nature of ZnO NS catalysts.

Enhanced gas-sensing to low-concentration ethanol gas from 3-dimensional (3D) urchin-like ZnO micro/nanospheres

Highly sensitive and long-term stable ethanol gas sensors based on 3D urchin-like ZnO micro/ nanospheres are synthesized. The formation mechanism of the 3D urchin-like ZnO structure is analyzed. The 3D urchin-like ZnO micro/nanospheres sensor displayed a high sensitivity of 15.0, a fast response time of 14 sec, and a recovery time of 7 sec when detecting 200 ppm ethanol gas at the optimal operating temperature of 280 °C. Moreover, the sensor is in the low concentration of ethanol gas for 450 days, in this case, the sensitivity of the sensor is 5.9, when detecting 200 ppm ethanol gas at an operating temperature 280 °C. The prepared 3D urchin-like ZnO micro/nanospheres have higher response strength to low-concentration ethanol gas and still have good stability after long-term storage

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.

Preparation and Photocatalysis Characteristics of Flower-like ZnO by Microwave Method

Flower-like ZnO was prepared by a simple and efficient microwave method at different microwave times. The effect of microwave time on the structure and morphology of the flower-like ZnO was analyzed systematically by XRD, SEM, PL and other equipment, the photocatalysis properties of flower-like ZnO were analyzed systematically through the degradation effect of ZnO on methyl orange. With the increase of microwave time, the shape of flower-ZnO was changed, it was bud at 10 min, then became flower-like gradually, and stacked reunion at 40 min. photoluminescence results showed green emission peaks at 536nm, photoluminescence intensity of ZnO prepared at 20 min was weakest, the photocatalytic efficiency of ZnO were not the same at different times, photocatalytic efficiency of ZnO prepared at 20 min and 40 min were 67% and 58.3% respectively, and photocatalytic efficiency of ZnO prepared at 10 min, 15 min, 30 min were 86.7%, 87.1%, 82.1% respectively.