ZnO Phase Research Articles

Understanding the Variations of Optical Bandgap in AZO Nanostructured Thin Films: Analysis of Possible Influences

Aluminum doped zinc oxide (AZO) thin films with varying thicknesses are fabricated using radio frequency (RF) sputtering combined with substrate rotation. The films display distinct nanocolumnar structures characterized by a hexagonal ZnO phase and a noticeable shift of the primary diffraction peak to lower 2θ angles. Lattice parameters a and c are used to evaluate residual stress and structural relaxation, both of which vary with increasing film thickness. Despite these structural changes, the films consistently maintain an average optical transmittance close to 85% in the range of 400–900 nm. The absorption edge and bandgap energy shift toward lower photon energies, decreasing from 3.51 to 3.38 eV as the thickness increases. The interplay between residual stress, structural relaxation, and bandgap energy is analyzed, offering insights into the complex dynamics influencing AZO thin‐film fabrication and the potential effects of quantum confinement. Lastly, the findings are compared with recent studies on ZnO thin films.

A novel approach revolutionizing ZnO nanoparticle synthesis with CTAB surfactant and Spirulina palenthesis microalgae for enhanced antimicrobial performance

Zinc Oxide Nanoparticles (ZnO NPs) are highly efficient photocatalysts, applied in areas such as self-cleaning, antimicrobial protection, UV-blocking, and anti-fogging. Their photocatalytic performance depends on factors like size, shape, and surface area, which can be controlled through morphology. In this study, Cetyltrimethyl Ammonium Bromide (CTAB) was used as a template to design ZnO nanorods, with Spirulina plantesis acting as a capping agent to ensure uniform size distribution. CTAB, a cationic surfactant, reduces surface tension, enabling more even dispersion of ZnO particles in a sol-gel medium, as observed through SEM imaging. The study focused on modifying ZnO morphology by adjusting the CTAB molar ratio (10%, 20%, and 30%) to the Zn(NO3)2 precursor. Characterization techniques such as TGA-DTA, FT-IR, XRD, BET/BJH, UV-VIS-DRS, and SEM were employed. Results showed that CTAB significantly reduced ZnO crystal size, improving particle homogeneity, with average sizes of 30.7, 29.8, and 27.6 nm, compared to 32.5 nm without CTAB. XRD analysis confirmed the ZnO phase with a P63mc space group (a = b = 3.25254 Å, c = 5.2110 Å, α = β = 90°, γ = 120°). The most enhanced photocatalytic activity was observed in the ZnO-CTAB-20 formulation, particularly in antibacterial tests against Staphylococcus epidermidis and Pseudomonas aeruginosa.

New Developed (Ag)-La$$_2$$O$$_3$$-Ce$$_4$$O$$_7$$-ZnO Photocatalytic Active Composites for Textile Dyes Degradation

New La2O3-Ce4O7-ZnO photocatalytic active composites were synthesized using Pluronic-assisted co-precipitation route, followed by calcination at 450° C. The silver doping of the prepared La2O3-Ce4O7-ZnO material was performed by impregnation with aqueous solution of AgNO3. The average crystallites size 3 nm and 39 nm for Ce4O7 and ZnO phases were estimated by PXRD analysis. The XPS study determined that the La3d5/2 peak is positioned at 834.1 eV and corresponds to La2O3. The binding energy of the Ag3d5/2 peak of the Ag-La2O3-Ce4O7-ZnO powder is at 367.2 eV and the amount of the silver on the surface is 0.8 at%. The obtained values of the modified Auger zinc and silver parameter are 2010.5 eV and 724.4 eV and correspond to Zn2+ and Ag2+ oxidation states, respectively. The silver doping enhances the photocatalytic efficiency of La2O3-Ce4O7-ZnO sample for degradation of Reactive Black 5 dye (78%) at 150 min UV irradiation compared to that of the undoped sample (52%). The undoped sample demonstrates the higher photocatalytic ability for degradation of Malachite Green dye (degree of degradation at 150 min – 80%) in comparison with Reactive Black 5 dye (52%).

The Effect of Post Heat Treatment on the Microstructure and Mechanical Properties of Cold-Sprayed Zn-6Cu Deposits.

To explore the feasibility of preparing Zn alloy bulk, Zn-6Cu deposit was prepared by cold-spraying additive manufacturing. Microstructure, tensile and wear behavior were investigated before and after heat treatment. Cold-sprayed Zn-6Cu deposit was constituted by irregular flattening particles and pores after heat treatment. Zn-6Cu deposits were composed of Zn and CuZn5 phases in addition to ZnO phase regardless of heat treatment, but the full width at half maximum of both the CuZn5 and the Zn phase were varied. The yield strength and ultimate tensile strength of Zn-6Cu deposits after post heat treatment were, respectively, increased from 83.8 ± 28.7 MPa and 159.6 ± 44.5 MPa to 89.4 ± 24.4 MPa and 223.8 ± 37.1 MPa. Fracture morphology after tensile testing exhibited main features of dimples, pores and cleaving particles. The friction coefficient and wear rate of Zn-6Cu deposits were increased after heat treatment, and the corrosive wear exhibited a lower friction coefficient and wear rate than the dry wear due to the lubricant of simulated body fluid. Grooves and localized delamination were the main wear features of Zn-6Cu deposits regardless of both the heat treatment and wear condition. This result indicates a potential application of cold-sprayed Zn-6Cu deposits comparable to the casting ones.

Structural, morphological and dielectric properties of Ni-doped ZnO nanoceramics prepared by Sol-gel method

Abstract The objective of this work is to synthesize new set of nanoceramics that improves structural integrity and dielectric performance while maintaining the desired characteristics of ZnO with the introduction of regulated Ni-doping. By using the sol-gel process, Ni-doped ZnO nanoceramics were successfully synthesized. Zn1–xNixO (x = 0, 0.05, 0.01, 0.15) wt % of Ni in to Zn precursor salts were added. Doping levels are considered to be low to moderate level, which typically lead to considerable changes in structural, optical, morphological and dielectric properties without modification of the nature of host ZnO. Higher concentrations greater than 15 % can result in the precipitation of isolated Ni or NiO phases which may negatively influence uniformity and consistency of the doped material. By using XRD for structural study, phase purity and the hexagonal wurtzite structure were confirmed. The integration of Ni2+ ions into the ZnO lattice is indicated by the change in lattice parameters and bond length for the Ni-doped ZnO sample. Samples follow almost same c/a ratio of an average of 1.601. An increase in “Ni” content results a decrease in crystallite size. Average crystallite size has been calculated ranging from 43.88 nm to 17.01 nm for ZnO to Zn0.85Ni0.15O samples. According to SEM analysis, the grains of the samples are uniformly dispersed. When the produced NPs were examined for purity using EDAX analysis, it was found that the beginning stoichiometries and the chemical composition of Zn, Ni, and O agreed well. The development of the ZnO phase was verified by the presence of a peak at 523 cm−1 in the FTIR spectra. According to the findings of X-ray photoelectron spectroscopy (XPS), Ni was observed to be present in the ZnO lattice in the form of Ni2+.The Koops phenomenological theory and the Maxwell-Wagner model provide an explanation for the observed dielectric behaviour. It is noted that for pure ZnO, the dielectric constant and dielectric loss have maximum values, whereas for doped samples, these values decreases. Our sample is suitable for high frequency device application due to a negligible dielectric loss of 0.047 at 15 % Ni concentration in the high-frequency region. Ni-doping affects AC conductivity. At 10 MHz, Zn0.9Ni0.1O has the highest AC conductivity (2.654 × 10⁻⁴ (Ω cm)⁻1), while Zn0.85Ni0.15O shows a lower value (1.048 × 10⁻⁴ (Ω cm)⁻1), indicating a balance between doping level and grain boundary influence on conduction. The impedance study reveals that just one semicircle in all samples, indicating that the influence of grain boundaries is more significant than the contribution of individual grains.

Synthesis and characterization of spent coffee grounds derived activated carbon-supported ZnO for photocatalyst

Abstract Spent coffee grounds derived activated carbon-supported ZnO as photocatalyst has been synthesized. This study analyzes the characteristics of adding activated carbon from spent coffee grounds to ZnO as a candidate photocatalyst material. The stages in this research are preparing activated carbon from spent coffee grounds, synthesis of ZnO/activated carbon, and characterization of ZnO/activated carbon. Based on the activated carbon quality test results, 13% ash content and 6.6% ash content were obtained, which met the standards. ZnO/activated carbon characteristics showed that all samples of activated carbon addition of 0.4 g, 0.9 g, and 1.4 g showed the dominant crystalline phase of ZnO. Adding 1.4 g activated carbon to ZnO gives suitable characteristics as a photocatalyst, resulting in a particle size of 45.22 nm and a band gap energy of 3.20 eV.

The effect of annealing on the structural, optical, electrical and photoelectric properties of ZnO/NiO heterostructures

In this study, n-ZnO/p-NiO heterostructures on glass substrates with an indium tin oxide (ITO) covering were obtained by using the spray pyrolysis methodology. In order to act on the structural and local compositional defects, the samples were annealed under vacuum in the temperature range of Ta = (300 – 500)°C in steps of ΔT = 50°C. X-ray diffraction results indicate the presence of only the hexagonal ZnO and cubic NiO phases in the studied samples, which was confirmed by Raman spectroscopy. Low-temperature photoluminescence (PL), as well as absorption and photoconductivity, were studied to establish the optical properties, the nature of electronic optical transitions, the energy level position of the different defects present in the samples, and the effect of temperature annealing on these properties The band gap of the compounds was determined using the Tauc approximation and the first derivative of the absorption coefficient. Likewise, the current-voltage characteristics of the n-ZnO/p-NiO heterostructures and their diode character, were analyzed.

Photocatalytic degradation of Rhodamine B using a reusable and magnetically separable Fe3O4/rGO/ZnO nanocomposite synthesized through green approach utilizing plant leaf extracts

We propose the magnetically separable, green synthesis of Fe3O4/rGO/ZnO using a higher mass ratio of Fe3O4/rGO and varying ZnO concentration to degrade an aqueous solution of Rhodamin B under Fenton reaction and UV light irradiation. Fe3O4 had been synthesized under the coprecipitation method utilizing Moringa oleifera leaf, while rGO had been fabricated by sonicating GO utilizing Amaranthus viridis leaf. Afterward, Fe3O4/rGO was composited under a facile method with a mass ratio of 5:5. And the last, Fe3O4/rGO/ZnO was green-synthesized through precipitation method using Amaranthus viridis leaf with various molarity ratio of Fe3O4/rGO: ZnO equal to 1:1, 1:2, 1:3, 1:4, and 1:5. X-ray diffraction revealed the presence of Fe3O4 and ZnO phases, while Raman spectroscopy confirmed the successful reduction of GO to rGO. The morphological analysis demonstrated that the particles were nearly spherical, nonuniform, and slightly dispersed, with some agglomeration observed on the rGO sheets. Fourier-transform infrared spectroscopy identified metallic functional groups, including Fe–O and Zn–O, at 524–570 cm−1 and 447–462 cm−1, respectively. However, redshift absorption and band gap narrowing were observed as the ZnO concentration increased. Photoluminescence analysis revealed that increased ZnO concentration reduces recombination and improves charge separation efficiency. The vibrating sample magnetometer exhibited soft magnetic properties. The magnetization of Fe3O4/rGO saturated at 21.7 emu/g and diminished as incorporated ZnO. The photodegradation increased with the increase of ZnO concentration, reaching its optimum at 1:5, about 89.9%. Fe3O4/rGO/ZnO demonstrates a possible ecologically friendly photocatalyst for wastewater remediation. The photocatalyst can be reused for up to three cycles with no significant change in its performance. Scavenger evaluation indicates that electrons and holes are the predominant reactive species in the photocatalytic reaction involving Fe₃O₄/rGO/ZnO.

Direct synthesis of liquid hydrocarbons from CO2 and H2 over bifunctional ZnCrOx-НZSM-5 combined and composite catalysts in a single reactor

A one-stage synthesis of gasoline fraction from CO2 and H2 was carried out on Zn–Cr–oxide-zeolite combined and composite catalysts. It was found that after oxidative and reduction treatment the catalysts contain ZnO and ZnCr2O4 phases. The one-step coprecipitation of zinc and chromium salts in the presence of zeolite allows obtaining an active bifunctional composite catalyst, each particle of which contains Zn–Cr oxide and zeolite components. A synergistic catalysis due to a closer distance of metal and acid sites increased the efficiency of such a catalyst in CO2 hydrogenation. It was found that the optimal temperature of oxidative activation of the composite catalyst is 400 °C. With an increase in the temperature of oxidative treatment of the composite catalyst from 400 to 500 °C, part of the zinc leaves the structure of the non-stoichiometric spinel and leads to a decrease in the basicity of the catalyst, which is responsible for the activation of CO2 on surface oxygen vacancies. Agglomerated ZnO particles blocked the pores and reduced their volume, as well as the specific surface of the catalyst. At the same time, the total acidity of the catalyst decreased. ZnO-species, which have hydrogenating activity, under the reaction conditions removed alkenes from the reaction cycle and thereby reduced the C5+–selectivity of the composite catalyst. Among the studied catalysts, the ZnCrOx-НZSM-5/Al2O3(400) composite catalyst in the tail-gas recirculation mode at 380 °C and 10 MPa demonstrated high CO2 conversion of 25% and high selectivity for C5+–HCs of 53 wt% with a high content of isoalkanes 71 wt% for 60 h. The methane content in the tail-gas did not exceed 3 vol%. The results obtained will be used to develop approaches to creating effective catalysts for one-stage CO2 hydrogenation into valuable petrochemical products.

Exceptional photocatalytic performance of hexagonal ZnO nanorods for anionic and cationic dyes degradation

This study presents an in-depth investigation of zinc oxide hexagonal nanorods (ZnO NRs) synthesized via a hydrothermal approach at three pH basic values conducted in high-pressure laboratory reactor provided by Parr Instrument Company. The research evaluates the catalytic properties of the ZnO NRs, highlighting their potential for environmental applications. The as-fabricated samples are characterized by various techniques including the X-ray diffraction (XRD), UV–visible spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), Brunauer–Emmett–Teller (BET) analysis, Field emission-scanning electron microscopy (FE-SEM), energy dispersive X-ray analysis (EDAX) and high-resolution transmission electron microscopy (HR-TEM). Rietveld refinement of X-ray diffraction data reveals the formation of high-purity hexagonal Wurtzite-type ZnO phase. Further, it is investigated that by decreasing the pH values, the grain size of ZnO NRs increases from 25.70 nm to 29.91 nm. SEM analyses further confirmed the hexagonal nanorod-shaped morphology of ZnO. The photocatalytic degradation performance of the as-fabricated ZnO NRs for Methylene Blue (MB) and Methyl Orange (MO) dyes increased with the increase in pH value, reaching almost 95 % and 64 %, respectively, after 30 min of UV irradiation. The optimum degradation is achieved at a pH value of 11.

ZnO/SnO2 based composite heterostructure for NO2 gas sensing properties

In recent years, interest in heterostructures and research on them has been increasing day by day. While semiconductors mainly exhibit different characteristics, they can exhibit different characteristics when they come together to form a heterostructure, and investigating the reasons for these is of great interest. For this purpose, in this study, such a hetero structure (ZnO/SnO2) was obtained by the Sol-Gel Dip Coating (SGDC) combined method and its effects on its characteristics against NO2 gas were tried to be examined.In this study, SnO2/ZnO composite heterostructures were grown by SGDC method. In this sense, this study is a first in the literature in terms of enlarging this structure with the SGDC technique. The number of SnO2 cycles was kept constant at 1 cycles and the ZnO layers were at different cycles as 1, 2, 3 and 5. The effect of ZnO cycles number on structural, morphological and most importantly NO2 gas detection properties was investigated in the formed heterostructures. In the XRD results, both ZnO and SnO2 peaks were observed and it was determined that these peaks belonged to the hexagonal wurtzite phase for ZnO and to the tetragonal rutile phase for SnO2. The lattice strain and crystallite size were calculated using Williamson-Hall and Scherrer method. The SEM images of ZnO-SnO2 manifest the change in the microstructure with increasing ZnO layer. The microstructure consisted of thin crystalline plates and small round-shape particles. The nano plates and walls shape and size changed with increasing ZnO layers. The operating temperature was defined as 165 °C for all sensors from NO2 gas sensing measurements. The responses of 1 ppm NO2 gas concentrations were calculated as 20 %, 201 %, 1078 % and 676 % for Z1S1, Z2S1, Z3S1 and Z5S1 heterosturucture respectively.

Effects of Pt doping on surface properties and quenching of band edge emission in ZnO

Pt doped ZnO thin films were synthesized on soda-lime glass substrates using a cost-effective sol-gel method, followed by spin coating and thermal annealing at various temperatures. Several characterization techniques such as UV–Vis absorption spectroscopy, photoluminescence (PL), field emission scanning electron microscopy (FESEM), time-of-flight secondary ion mass spectroscopy (ToF-SIMS), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS) are exploited to investigate the Pt doping effects on surface and optical properties of ZnO thin films. UV–Vis analysis demonstrated a slight decrease in the optical band gap from 3.3 eV to 3.2 eV with increased annealing, indicating enhanced suitability for optoelectronic applications. FESEM imaging revealed distinct worm-like structures and small Pt metal nanoparticles in unannealed samples, while thermal treatment supported the formation of spherical Pt nanoparticles and improved conductive pathways in the films. The Wagner diagram, coupled with Auger line transitions from XPS, quantified the oxidation states and chemical environments of Zn and Pt, respectively. Notably, the observed changes in the binding energy of the Zn-2p junction and the kinetic energy of the Zn-LMM Auger junction were significantly influenced by the Pt doping and the electronic properties of the substrate. The Wagner diagram provided a comprehensive visual representation of the parameters, facilitating a deeper understanding of electronic interactions and structural dynamics at the atomic level. XPS results confirmed the presence of ZnO, Zn(OH)2, Pt0 and PtO2 phases, indicating stability and constutient's interactions. ToF-SIMS also validated the uniform distribution of Pt nanoparticles within the ZnO thin film, confirming the effectiveness of the sol-gel method. As a result of Pt doping, PL studies revealed a large quenching effect on band edge emission in the UV and visible emission region of ZnO thin film, which is due to Pt acting as a recombination center for photogenerated carriers. Overall, our results highlight the influence of annealing and Pt incorporation on the optical and structural properties of ZnO thin films and highlight their potential applications for photonics and catalysis.

Preparation, characterization and biological activity of Co-doped ZnO nanostructured thin film: A comprehensive study on its photo-physical properties and antimicrobial efficacy against food-borne pathogen

The Co@ZnO thin film deposited on glass substrate with dopant contents of cobalt ranging from 0 to 10 % were fabricated using spray pyrolysis coating method. The prepared nanocomposite thin film was characterized by scanning electron microscopy, X-ray diffraction, UV–vis and Raman spectroscopy. Some surfaces structural probing of the deposited samples confirmed nanolamination of hexagonal wurtzite phase of ZnO with no other impurity phases and high adherence on the soda lime glass substrate. Average grain sizes (56–43 nm) and lattice strain of the films were found to be tailored with the variation of Co-dopant content, signifying phonon confinement or defect/disorder caused by the Co-dopant impurity on the ZnO host particle owing to the impurity levels and oxygen vacancy states. The film demonstrated high optical transmittance with enhanced photoabsorbtion and narrow optical band gap (3.24–2.64 eV) with increasing Co-dopant content. In evaluating its antibacterial efficacy, the Co@ZnO thin film was tested at different dopant concentration against Bacillus cereus (foodborne pathogen). The result revealed that the films exhibits excellent inhibitory effect on the pathogen, with highest activity obtained at 10 % Co@ZnO. Furthermore, a more improved inhibitory activity was recorded when at 10 % Co@ZnO dopant was exposed to UV irradiation.

Microstructure and Mechanical Properties of Silicon Carbide-Reinforced Aluminum Matrix Composite Based on Al–Mg–ZnO Phase

Microstructure and Mechanical Properties of Silicon Carbide-Reinforced Aluminum Matrix Composite Based on Al–Mg–ZnO Phase

Effect of laser heating on partial decomposition of ZnCo2O4 nanoparticles: Raman study

We conducted a comprehensive investigation into the nanostructuring of the ZnO/CoO mixture by laser heating and optical attributes of partial decomposition of the obtained two-phase system represented by ZnO and ZnCo2O4. Starting mixtures were obtained across a broad range of dopant, CoO, concentrations, spanning from 5 % to 90 % of CoO. The samples were methodically prepared using the coprecipitation method and subjected to calcination at 600 °C. Laser-induced heating experiments were conducted at nine distinct laser powers. The characterization of these samples was accomplished through the utilization of SEM, XRD, and Raman spectroscopy. XRD analysis unveiled the presence of ZnO and ZnCo2O4 phases. Concurrently, we systematically monitored nanostructuring effects caused by laser-induced heating, the influence of partial decomposition on the behavior of surface optical phonons (SOP), and phase transitions in the samples with varying dopant concentrations during the performed experiment. New phases, including Zn1-xCoxO, ZnyCo3-yO4, CoO, and even the Co3O4 phase, were unveiled. The Raman spectra obtained distinctly indicate the presence of surface optical phonons (SOP), emphasizing the existence of the ZnO phase. The alterations in the behavior of surface optical phonon (SOP) modes were meticulously examined by laser-induced heating nanostructuring effects where it became evident that there was a discernible loss of these modes with an increase in dopant concentration and laser power. This detailed study sheds light on the intricate interplay between dopant concentration, laser power nanostructuring, partial decomposition, and the evolution of phase transformations and surface optical phonon modes in the examined samples.

Physical properties of La:ZnO thin films prepared at different thicknesses using spray pyrolysis technique

Herein we investigate the impact of film thickness on the physical properties of Lanthanum (La) doped ZnO thin films. The films were fabricated using the spray pyrolysis technique with a consistent La content of 5 weight (wt) % in the initial solution. X-ray diffraction analysis indicated the presence of a hexagonal ZnO phase with preferred orientation along the (002) direction and no other phases were detected. The crystallite sizes were calculated using the Halder-Wagner equation, with a maximum size of 16.1 nm observed for a film thickness of 106 nm. Field-emission scanning electron microscopy (FE-SEM) images revealed the formation of a continuous film with an average grain size that increased as the thickness of the film increased. The grain size ranged from 74.5 to 136 nm as the film thickness varied from 106 to 426 nm. Films with lower thicknesses up to 196 nm exhibited two band gaps at approximately 3.2 and 4 eV, while films with higher thicknesses displayed a single band gap around 3.2 eV. The refractive index dispersion for all films was modeled using the Cauchy model, with parameters showing high dependence on the thickness values.The refractive index at high frequency, as calculated using the Cauchy model, was observed to decrease with increasing film thickness, ranging from 1.87 at 106nm to 1.63 at 426nm. Similar values were obtained by fitting the optical refractive index data with the Wemple-DiDomenico relation. Additionally, the UV sensing performance of the films was evaluated against UV light of a single wavelength (365 nm) at applied voltages of 10, 20, and 30V. The rise and decay times were measured, with the film thickness of 426 nm exhibiting the shortest rise and decay times at a specific applied voltage.

Ce-doped ZnO nanonails synthesized by a simple thermal evaporation method for photocatalytic degradation

One-dimensional (1D) nanomaterials have garnered significant scientific and technological attention due to their potential applications in electronics devices, gas sensing, energy conversion, and photocatalysis. However, the development of a simple and low-cost technique for 1D nanostructure synthesis remains a challenge. The doping of ZnO nanostructures has proven to be an effective way to improve their internal properties. In this work, one-dimensional ZnO and Ce-doped ZnO nanorods and nanonails were synthesized by a simple thermal evaporation method using different weight ratios of ZnS and CeO2 precursor powders in a catalyst-free process. The effects of cerium doping concentration on the structural, morphological, and optical properties of the as-prepared samples were investigated. XRD analysis confirmed that the crystal structure was converted from the cubic ZnS phase to the hexagonal ZnO phase with increasing annealing temperatures. The UV–Vis spectra showed that the optical absorption edge of Ce-doped ZnO samples was slightly red-shifted. Additionally, the band gap energy decreases with increasing cerium concentration. SEM images showed that the morphology of the structures obtained changed from nanorods to nanonails as the Ce content increased. The incorporation of Ce ions into the ZnO matrix has been successfully confirmed by HRTEM, Raman, and EDX analysis. Photocatalytic activity studies showed that Ce-doped ZnO samples exhibited significantly enhanced photocatalytic performance compared to pure ZnO for the degradation of rhodamine B under UV radiation. These results may suggest the use of heterogeneous photocatalysis as an efficient, cheap, and environment-friendly alternative for the removal of pollutants from water and the use of Ce-doped ZnO as a promising candidate.

Elemental Zn modulation of interfacial structure and in situ construction of (FeCoNiCuZn)O high-entropy oxide/ZnO heterojunction for photocatalytic Rhodamine B dyes

In this study, inspired by the lattice distortion effect of HEOs, we adopt a non-equimolar strategy, fixing the molar ratios of Fe, Ni, Cu, and Co while varying the molar ratio x of Zn/(FeNiCuCo) (x=0.25, 0.5, 1.0, 1.5 and 2.0) to synthesize the HEO-x compounds. With an increase in the Zn content, lattice distortion occurred in the spinel phase of the (FeNiCuZnCo)O HEO, resulting in the gradual precipitation of ZnO nanocrystals. The (220) crystal plane of the spinel phase closely connects with the (100), (002), and (101) crystal planes of the ZnO phase, forming nano-heterojunctions. The HEO-1.5 prepared by controlling the Zn element proportion exhibits a high photocatalytic degradation rate of Rhodamine B (RhB) of up to 99.45 %. The kinetic degradation rate of HEO-1.5 is 17 times higher than that of HEO-0.25, attributed to the nano-heterojunctions formed by the spinel phase and ZnO phase, facilitating effective separation of photogenerated electron-hole pairs, promoting the generation of active free radicals, and rapidly degrading RhB.

Electrodeposited zinc oxide nanoparticles: Synthesis, characterization, and anti-cervical cancer effects

In the present study, zinc oxide nanoparticles (ZnO NPs) were synthesized via the electrodeposition method and characterized. Then, the anticancer effects of ZnO NPs against cervical cancer HeLa cells were assessed by cell viability, oxidative stress, caspase activity, qRT-PCR, MMP, and ELISA assays. XRD analysis revealed the hexagonal wurtzite phase of ZnO. SEM image of ZnO NPs showed the homogeneous spherical/hexagonal-like structures of ZnO NPs, while TEM imaging revealed the successful synthesis of ZnO NPs with an average diameter of about 8 nm. The UV–vis absorption spectrum of ZnO NPs showed a characteristic absorption band around the wavelength of 368 nm with a band gap energy (Eg) of 3.36 eV. DLS study displayed that the obtained particle size of ZnO NPs has an average size of 29.24 nm and an average zeta potential value of −19 mV. Additionally, cellular findings indicated that the proliferation of cervical cancer HeLa cells was markedly mitigated after incubation with ZnO NPs at different concentrations of 10, 50 and 100 µg/ml, however, these concentrations were not able to trigger an apparent cytotoxic effect on HUVEC non-malignant cells. Also, it was detected that ZnO NPs led to overexpression of Bax/ Bcl-2, caspase-9/-3 genes, increased level of caspase-9/-3 activity, overproduction of MDA level, inhibition of SOD and CAT activity and reduction of GSH content, MMP collapse, and upregulation of cytoplasmic cytochrome c release. In general, these findings suggested that electrodeposited synthesized ZnO NPs can induce anticancer effects in cervical cancer HeLa cells through the mitochondrial-mediated apoptosis signaling pathway.

Optimized Chemical Bath Deposition for Low Cost, Scalable, and Environmentally Sustainable Synthesis of Star-Like ZnO Nanostructures.

This paper highlights an affordable and straightforward method called chemical bath deposition (CBD) for generating different morphologies of ZnO-based nanostructures. In particular, a specific protocol was found to drive the growth versus a high-yield in-plane symmetric six-arm nanostructure, named a nanostar (NS). Each arm of the star consists of a cluster of parallel wires, creating a subnanostructure with a huge surface-to-volume ratio. As-grown NSs present a mixed phase of ZnOHF and ZnO, which converts to ZnO under thermal annealing at 300 °C. The NSs have a highly exposed surface area (13.2702 m2·g-1) and exhibit an energy gap of 3.25 eV. A cradle-to-gate life cycle assessment (LCA) analysis has shown the high ecofriendly potential of this synthesis route and identified hotspots that need to be addressed to minimize the environmental impact of NS synthesis on an industrial scale.