ZnO Phase Research Articles

Exploring the Photoluminescence Property, Photocatalytic Efficiency, and Antibacterial Activity of Eu-Doped ZnO/SnO2 Heterostructure

In this study, nanocomposites of ZnO–SnO2 doped with Eu ions were synthesized by sol-gel method. The samples show the co-existence of hexagonal ZnO and tetragonal SnO2 crystallographic phases as observed from X-ray diffractometry studies. Eu doping facilitates the grain growth as the average grain size is found to increase with the increase in Eu dopant concentration. Surface morphology of the samples also gets altered with Eu doping with EDAX measurement giving the confirmation of existence of elements like Zn/Sn/Eu. FTIR measurement specifies the appearance of peaks linked with functional groups like Zn–O, Sn–O and O–H. Photoluminescence study shows the evolution of characteristic emissions of Eu ions (5D0→ 7F1, 5D0→ 7F2 and 5D0→ 7F3). Photodegradation of toxic environmental dyes like Congo red and methylene blue was executed and the efficiency of degradation was estimated under visible light illumination. The presence of Eu3+ ions in ZnO/SnO2 helps to enhance the degradation efficiency by facilitating to form Z- scheme heterojunctions between ZnO and SnO2. This allows the delay in recombination rate of the photoinduced electron/hole pairs. The antibacterial behavior of the prepared nanocomposites against E. coli and S. aureus has also been studied in detail which demonstrates improved antibacterial efficiency of the samples.

Non-doped phosphor for WLED with high CRI and R9

The effect of the ZnO/SnO2 ratio on phase formation and optical properties of the Zn-Sn-O compound was investigated by varying the ZnO/SnO2 molar ratio (ZnO/SnO2 = 1:2, 1:1, 2:1, 3:1, and 4:1). All samples were synthesised with high-energy planetary ball milling, followed by calcination at 1000 °C in the air. The result from X-Ray diffraction patterns (XRD) shows that the single-phase Zn2SnO4 is achieved at the ZnO/SnO2 ratio of 2:1. Whereas, the mixed phase of ZnO and Zn2SnO4 formed when ZnO is more than SnO2 (3:1 and 4:1). On the other hand, the XRD patterns of the products obtained at a ratio where SnO2 is more than ZnO present a mixture of SnO2 and Zn2SnO4. The photoluminescence of the two samples with the ratio of 2:1 and 1:3 gives full-visible range spectra from 400 to 800 nm, which are in the blue-far-red region centred at about 514, 580, and 690 nm. Temperature-dependent luminescence measurements were also carried out in this work, and the results indicate that the prepared phosphor Zn-Sn-O at the ZnO/SnO2 ratio of 1:2 has thermal stability. The obtained material was used to coat near UV LED chips, and the WLED possesses the highest CRI of 95. The SnO2-Zn2SnO4 powder can be used as a phosphor for WLED applications with high CRI and R9.

Molecular-level understanding of interfacial carbonates in stabilizing CuO-ZnO(Al2O3) catalysts

A descriptor of active CuO-ZnO(Al2O3) methanol-synthesis and water–gas-shift catalysts is the presence of high-temperature carbonates (HT-CO3) in the oxidic catalyst precursor. Previous reports have shown that such HT-CO3 lead to an appropriate interaction between the oxides; as a result, a high Cu surface area (or Cu-Zn or Cu/ZnO interphase areas) can be achieved. Yet, their nature is not well understood. In this study, the nature of these carbonates was investigated by experimental and theoretical methods in the oxidic precatalyst. A calcined Cu-Zn-Al hydrotalcite model compound revealed to have well-dispersed ZnO and CuO phases, together with highly stable HT-CO3. It was hypothesized that these HT-CO3 groups may be placed at critical locations at nano-scale as a glue, thus avoiding the growth of the oxide crystallites during calcination. This is an excellent pre-condition to achieve a high Cu surface area (or Cu-Zn or Cu/ZnO interphase areas) upon reduction, and therefore a high activity. To prove that, first-principles calculations were carried out based on the density functional theory (DFT); alumina was not considered in the model as the experimental data showed it to be amorphous but it may still have an effect. Comprehensive calculations provided evidence that such carbonate groups favourably bind the CuO and ZnO together at the interface, rather than being isolated on the individual oxide surfaces. The results strongly suggest that the HT-CO3 groups are part of the structure, in the calcined precatalyst, where they would prevent thermal sintering through a bonding mechanism between CuO and ZnO particles, which is a novel interpretation of this important catalyst descriptor.

The effect of ZnO:Si3N4 nanocomposite interlayer on electrical properties and interface-states between metal-semiconductor in Al/p-Si (MS) structures

In the study, the fabrication processes of the Al/p-Si (MS), Al/ZnO/p-Si (MIS1), and Al/(ZnO:Si3N4)/p-Si (MIS2) structures were described and the effect of the ZnO:Si3N4 interface layer in MS was investigated in detail. The ZnO and (ZnO:Si3N4) thin films were coated on p-Si substrates and annealed at 500 °C for 1 h. Si3N4 and ZnO phases were identified via X-ray diffraction (XRD) and Raman spectra. FESEM images demonstrated that ZnO nanorods grew on Si3N4 particles with a heterogeneous nucleation mechanism. The I–V characterization was performed in the dark (±4 V). The basic diode parameters (barrier height (BH), series/shunt (Rs/Rsh) resistances, rectifying rate (RR=If/Ir), and ideality factor (n)) were calculated from various methods. The RR, and Rsh values increased, but n, Rs and BH decreased by insulating layer in the MIS2 The energy-dependent profiles of interface-states (Nss) were also extracted from the I–V plots according to voltage-dependent n and BH. The MIS2 provided the best passivation effect with decreasing interface traps.

Ternary Metal (Cu-Ni-Zn) Oxide Nanocomposite via an Environmentally Friendly Route.

In this work, we report the engineering of sub-30 nm nanocomposites of CuO/ZnO/NiO by using Dodonaea viscosa leaf extract. Zinc sulfate, nickel chloride, and copper sulfate were used as salt precursors, and isopropyl alcohol and water were used as solvents. The growth of nanocomposites was investigated by varying the concentrations of precursors and surfactants at pH 12. The as-prepared composites were characterized by XRD analysis and found to have CuO (monoclinic), ZnO (hexagonal primitive), and NiO (cubic) phases with an average size of 29 nm. FTIR analysis was performed to investigate the mode of fundamental bonding vibrations of the as-prepared nanocomposites. The vibrations of the prepared CuO/ZnO/NiO nanocomposite were detected at 760 and 628 cm-1, respectively. The optical bandgap energy of the CuO/NiO/ZnO nanocomposite was 3.08 eV. Ultraviolet-visible spectroscopy was performed to calculate the band gap by the Tauc approach. Antimicrobial and antioxidant activities of the synthesized CuO/NiO/ZnO nanocomposite were investigated. It was found that the antimicrobial activity of the synthesized nanocomposite increases with an increase in the concentration. The antioxidant activity of the synthesized nanocomposite was examined by using both ABTS and DPPH assays. The obtained results show an IC50 value of 0.110 for the synthesized nanocomposite compared to DPPH and ABTS (0.512), which is smaller than that of ascorbic acid (IC50 = 1.047). Such a low IC50 value ensures that the antioxidant potential of the nanocomposite is higher than that of ascorbic acid, which in turn shows their excellent antioxidant activity against both DPPH and ABTS.

Influence of dopants on the structure and catalytic features of the Cu/ZnO catalyst for dimethyl oxalate hydrogenation to ethylene glycol

The Cu-M/ZnO catalysts (M = Zr4+, Al3+ and Mg2+) for dimethyl oxalate (DMO) selective hydrogenation to ethylene glycol (EG) were synthesized by the co-precipitation method. The properties of the as-synthesized catalysts were characterized by N2-physisorption, N2O-titration, XRD, H2-TPR, CO2-TPD, SEM, FT-IR and XPS. It was found that the Cu dispersion could be effectively promoted by the dopants incorporated in the Cu/ZnO catalyst. Particularly, a trace amount of Mg2+ and Al3+ dopants could significantly reinforce the chemical interaction between the Cu and ZnO phases by embedding into the ZnO lattice, while the Cu/ZrO2 interaction could be improved with the introduction of Zr4+. For DMO gas-phase hydrogenation, the EG yield of the Cu/ZnO catalyst increased from 75.0% to 85.0% and 90.0% in the presence of Zr4+ and Al3+ dopants, respectively. Particularly, the EG selectivity of Cu-Mg/ZnO catalyst reached up to 95.0% with DMO completely converted for more than 100 h. The correlation between the catalytic behavior and physicochemical features of the Cu/ZnO based catalysts suggested that the surface Cu+ sites was vital for the catalytic behavior with adequate Cu0 sites. Additionally, the strengthened Cu/oxide interaction favored the outstanding stability of the Cu-Zr/ZnO and Cu-Mg/ZnO catalyst for DMO hydrogenation.

Antibacterial potential of zinc oxide nanoparticles derived from pineapple peel aqueous extract

Pineapple peel waste contains antioxidant molecules. This paper describes a facile, efficient, and environmentally friendly approach for synthesizing ZnO nanoparticles using pineapple peel aqueous extract. This method aims to reduce the use of harmful chemicals in producing ZnO nanoparticles using zinc nitrate as a salt precursor and evaluating their antibacterial. Pineapple peel aqueous extract was obtained by macerating pineapple peel powder in distilled water. Engaging Zn(NO3)2, pineapple peel aqueous extract, and NaOH, ZnO NPs were successfully prepared by biosynthesis. X-ray diffraction (XRD) analysis and Fourier transform infrared (FTIR) spectroscopy was utilized to confirm the formation of ZnO NPs, while scanning electron microscopy (SEM) was employed to see the morphology and size distribution of nanoparticles. The antibacterial activity of pineapple peel extract-ZnO nanoparticles (pp-ZnO NPs) against Gram-positive and Gram-negative bacteria was evaluated by an agar disc diffusion method. The SEM images showed that by applying pineapple peel aqueous extract, the pp-ZnO with an average size below 100 nm with a mixture of flakes and rod-like shapes were obtained. The XRD pattern confirmed the wurtzite phase of ZnO, while antibacterial assay results showed that the pp-ZnO actively inhibited B. subtilis and E.coli. at concentrations of 5 and 10 wt%. Therefore, phyto-assisted synthesis mediated by pineapple peel wastes is a promising green approach to preparing ZnO nanoparticles.

Synthesis of ZnO nanoparticles by precipitation method: Characterizations and applications in decipherment of latent fingerprints

Here in we present the synthesis of phase pure ZnO nanoparticles using precipitation method. X-ray Diffraction (XRD) and UV–Visible spectroscopy were used to characterize the synthesized ZnO nanoparticles. The observed data is in good agreement with previously reported XRD data of ZnO nanoparticles (JCPDS File number 36–1451) which confirms the synthesis of pure phase ZnO nanoparticles. Scherrer formula was used to calculate the crystallite size of the synthesized ZnO nanoparticles. The band gap of synthesized Zinc oxide nanoparticles was obtained using UV–Visible spectroscopy. We used these ZnO nanoparticles’ powder for latent fingerprint (LFP) development. The developed fingerprints were tape lifted using normal cellophane tape and was pasted over a dark background surface. Photography was done before and after the lifting process and was sticked over a dark surface.

Zn-In-O electrocatalysts with co-existing ZnO and In2O3 phases for efficient reduction of CO2 to formate through sacrificial mechanism

Electrochemical CO2 reduction reaction (eCO2RR) is considered an efficient approach to produce value-added chemicals and fuels. In this paper, a series of MOF-derived composite catalysts with coexisting In2O3 and ZnO are fabricated using a simple process for eCO2RR to produce formate. The Zn-In-O/800 catalyst achieves a formate Faradaic efficiency (FEHCOO−) of 94.25 % at −1.16 V vs. RHE, which can maintain over 89 % after 30 h in a stability test. The electrochemical evidence and density functional theory analysis show that the strong interface effect between In2O3 and ZnO can enhance the CO2 adsorption and activation, and promote the conversion of CO2 to formate. In addition, the ZnO phase can protect In2O3, as the main active site, from being reduced to a certain extent for a long time under negative potential, which ensures the high stability of the composite catalyst.

Synthesis, Characterization and Impedance Analysis of CalciumDoped Zinc Oxide Nanoparticles

The calcium-doped ZnO nanoparticles, Zn1-xCaxO (x = 0, 0.025, 0.05, 0.075) were prepared by the solution combustion method. The synthesized nanoparticles were characterized by various techniques such as XRD, FTIR, Raman, FESEM-EDX, PL, Impedance, and UV-Vis. The Rietveld refinement of the X-ray diffractogram yields the crystalline structure and lattice parameters. Also, the XRD analysis shows that the substitution of Ca into ZnO does not alter the Wurtzite structure of ZnO. The crystallite size of the samples, calculated using the Scherer equation, was found to be between 46 nm and 92 nm. FTIR spectra detect the ZnO-related vibration modes of the samples. The FESEM morphological images suggest the spherical shape of the synthesized nanoparticles. The EDAX spectra identify the presence of Zn, Ca, and O atoms in the samples. The Raman active modes of the ZnO phase were identified by Raman spectral analysis. The analysis of Photoluminescence (PL) spectra gives information about the UV emission and other visible bands corresponding to violet, blue, and green emission representing different intrinsic defects in synthesized nanoparticles. Using UV-vis spectroscopy, the optical transparency and band gap values were examined. The energy band gap obtained by Tauc’s plot was decreased with the increase in Ca doping. Impedance analysis shows that the grain conductivity increased with the increase in dopant concentration. Contrarily, the total conductivity decreased with the increasing doping concentration due to increased grain boundary resistance. The proposed work demonstrates the changes in microstructure, electrical conductivity, and optical bandgap energy with Ca-doping. These synthesized Ca-doped ZnO nanoparticles could be promising materials for photocatalytic applications.

Simultaneously enhanced aromatics selectivity and catalyst lifetime in methanol aromatization over [Zn, Al]-ZSM-5 via isomorphous substitution with optimized acidic properties and pore structure

Zinc-modified HZSM-5 zeolites as efficient catalysts have been widely applied in methanol to aromatics (MTA) reactions, however, the relationship between aromatics selectivity and catalytic stability in traditionally loaded catalysts seems to be a stubborn trade-off. To improve both catalytic indicators simultaneously and reveal the relation of the states of introduced Zn species to the consequential influence in physiochemical properties, a series of [Zn, Al]-Z5 zeolites with different Zn contents were prepared via isomorphous substitution under a fixed Si/Me (Me = Al or Al and Zn) ratio. Results revealed that there were three possible states of the introduced Zn species, namely the highly-dispersed ZnO phase, the Zn(OH)+ occupying the ion-exchange sites, and the tetra-coordinated ZnO42- integrated into the zeolite framework. A portion of Zn was successfully integrated into the five-membered rings of zeolite in the form of Si-O(H)-Zn, which played the role of strong Brönsted acid sites and led to the formation of hierarchical structures aside from the intrinsic micropores. Besides, extra-framework Zn(OH)+ was formed by the interaction between dissociate Zn species and the Si-O(H)-Al structure, giving rise to larger proportions of Lewis acid sites. Benefitting from the optimized acidic properties and pore structure, 0.5[Zn, Al]-Z5 exhibited higher aromatics selectivity and longer catalyst lifetime (26.0% and 132 h) than [Al]-Z5 without Zn addition (19.6% and 52 h) in methanol aromatization. Overall, our findings opened a new way to improve the efficiency of MTA reaction and broadened the method to obtain metal-modified zeolite catalysts.

Antibacterial activity of green synthesized ZnO nano-flower using pineapple peel extract

Plant-based nanoparticles provide significant advantages over conventional physico-chemical techniques in medicine and biology. This paper reports the green route to synthesise ZnO particles using pineapple peel extract at various zinc precursor concentrations and evaluate their antibacterial activity. Morphological, structural, and optical properties of ZnO were characterised using SEM, XRD, FTIR, and UV–vis. The antibacterial potential of ZnO particles was evaluated against two clinical strains of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) using the paper disc diffusion method. SEM images exhibit flower-like ZnO with diameters in the range of 331–538 nm. The hexagonal wurtzite crystal phase of ZnO has been confirmed by XRD analysis with a crystal size of 14–17 nm. The FTIR spectrum has also validated the Zn-O bonding and the presence of additional functional groups in the samples. Antibacterial activity of the nanoflower ZnO towards E. coli and S. aureus displays inhibitory zone widths of 17.23 ± 3.03 mm and 30.14 ± 1.86 mm, respectively. These findings reveal that nanoflower ZnO produced using the pineapple peel extract exhibited a large bacterial inhibition zone, indicating that it is potentially used as food packaging or antibiotics.

Enhancement of Microwave Absorption Properties of Hexaferrite/Epoxy Composites on the Addition of Non-magnetic Oxides

The effect of non-magnetic oxides such as Al2O3, TiO2 and ZnO on the microwave absorption properties of magnetoplumbite barium hexaferrite (BaFe11.8Co0.2O19) is analyzed. Barium hexaferrite nanoparticles are synthesized through the sol-gel auto-combustion method. BaFe11.8Co0.2O19-Al2O3, BaFe11.8Co0.2O19-TiO2 and BaFe11.8Co0.2O19-ZnO composites are synthesized in a 1:1 ratio through mechanical mixing and heat treatment. The epoxy composites are fabricated with 50% loading of BaFe11.8Co0.2O19-Al2O3, BaFe11.8Co0.2O19-TiO2 and BaFe11.8Co0.2O19-ZnO in epoxy matrix followed by room temperature curing. The powder XRD analyses showed homogeneous distribution of BaFe11.8Co0.2O19 and Al2O3 in BaFe11.8Co0.2O19-Al2O3 composite while TiO2 and ZnO phases dominate in BaFe11.8Co0.2O19-TiO2 and BaFe11.8Co0.2O19-ZnO composites, respectively. Scanning electron microscopy shows the evenly distributed BaFe11.8Co0.2O19 and Al2O3 in BaFe11.8Co0.2O19-Al2O3 composites. The electromagnetic characterization calculated from experimental permittivity and permeability shows reflection loss RL ≤ -10 dB (≥ 90% absorption) for a very small thickness of 0.5 mm over the entire X-band (8-12 GHz) for BaFe11.8Co0.2O19-Al2O3 composites. BaFe11.8Co0.2O19-TiO2 and BaFe11.8Co0.2O19-ZnO show RL < - 8 dB with a thickness of 2.5 mm over the frequency range 8–9.7 GHz and RL < - 8 dB with a thickness of 3.6 mm over 8.7-11.1 GHz, respectively. Further, when compared with BaFe11.8Co0.2O19 alone (RL < -7 dB at 3.2 mm in 8-11 GHz), the BaFe11.8Co0.2O19-Al2O3 composite is superior both in terms of the thickness of the coating as well as the percentage absorption in the X-band.

Enhancement of UV detection properties of ZnO thin films via Ni doping

In this work, pure and Ni-doped ZnO thin films have been deposited onto glass substrates using the spray pyrolysis technique. All films were deposited at constant deposition parameters but the Ni content was changed from 0 to 7 weight (wt) %. XRD results revealed the formation of a hexagonal ZnO phase whilst no other phases were detected. The crystallite size was determined using Scherrer’s equation and found to be 45.9 nm for the pure film. Scanning electron microscope images show the formation of irregular grains with a broad size distribution. The existence of Ni in the deposited films was confirmed using energy dispersive spectroscopy (EDX), where the Ni content in the film increases as the weight % increases in the starting solution. The optical band gap was determined and found to be 3.3 eV for the pure ZnO films, which was reduced with Ni doping. The performance of the deposited films for UV radiation has been examined for the 365 nm wavelength and at different applied potentials and constant power. The rise and decay times for doped films were observed to exhibit faster rise/recovery as compared to pure films. The minimum response time was found to be 0.09 s for Ni-7 wt% film and the minimum decay time is 0.07 s for Ni-1 wt%.

Effects of Dopants and Processing Parameters on the Properties of ZnO-V2O5-Based Varistors Prepared by Powder Metallurgy: A Review.

This article reviews the progress in developing ZnO-V2O5-based metal oxide varistors (MOVs) using powder metallurgy (PM) techniques. The aim is to create new, advanced ceramic materials for MOVs with comparable or superior functional properties to ZnO-Bi2O3 varistors using fewer dopants. The survey emphasizes the importance of a homogeneous microstructure and desirable varistor properties, such as high nonlinearity (α), low leakage current density (JL), high energy absorption capability, reduced power loss, and stability for reliable MOVs. This study investigates the effect of V2O5 and MO additives on the microstructure, electrical and dielectric properties, and aging behavior of ZnO-based varistors. The findings show that MOVs with 0.25-2 mol.% V2O5 and MO additives sintered in air over 800 °C contain a primary phase of ZnO with a hexagonal wurtzite structure and several secondary phases that impact the MOV performance. The MO additives, such as Bi2O3, In2O3, Sb2O3, transition element oxides, and rare earth oxides, act as ZnO grain growth inhibitors and enhance the density, microstructure homogeneity, and nonlinearity. Refinement of the microstructure of MOVs and consolidation under appropriate PM conditions improve their electrical properties (JL ≤ 0.2 mA/cm2, α of 22-153) and stability. The review recommends further developing and investigating large-sized MOVs from the ZnO-V2O5 systems using these techniques.

Formation Mechanism and Excitonic Luminescence of Supercritical-Fluid-Synthesized ZnO Nanoparticles

Extensive research on nanosized ZnO has proven that its optical properties are challenging to control due to a number of possible defects producing various emissions in the visible range. Our group proposed a low-temperature, supercritical-fluid-driven synthesis of isotropic nanosized particles that exhibit a unique and unprecedentedly pure excitonic emission, comparable to that of single crystals. The present article reports the growth mechanism at the origin of the unexpectedly pure excitonic emission as well as a more detailed study of its optical properties at liquid helium temperatures. The ZnO phase is obtained via the thermal decomposition of an intermediate ZnO2 phase. No bulk defect luminescence is detected, and the synthesis route leaves a “ZnO2-like” surface able to neutralize the formation of surface defects, which can contribute to visible emissions. The luminescence measurements were performed at liquid helium temperature to enable the identification of excitons. The investigation of the photoluminescence properties confirms a strong excitonic emission in the UV region with no visible band and sheds light on a phonon coupling with the E2 high vibrational mode.

Seedless and surfactant-free growth of flower-shaped ZnO nanostructures: Growth evolution mechanism

In this work, an innovative seedless and surfactant-free chemical bath deposition (CBD) method at low temperature was applied to obtain flower-shaped ZnO nanostructures (FZONSs) on glass and [Formula: see text]-type silicon substrates for the first time. Structural properties of these FZONSs were examined. The NSs were produced from zinc nitrate hexahydrate and hexamethylenetetramine, HMTA solution without any catalyst, template, or seed layer. An electric soldering iron pen was used to simultaneously heat the substrate and aqueous mixture of the constituents to grow the FZONSs. Field emission scanning electron microscopy images of the samples showed the presence of three-dimensional (3D) flower-shaped nanomorphology. Energy-dispersive X-ray spectroscopy detected the right trace elements in the FZONSs. X-ray diffraction analysis of the as-grown samples confirmed the existence of high purity nanocrystalline hexagonal phase of ZnO with preferred growth along (002) lattice planer orientation. The growth of ZnO nanorods into unified flower-like morphology was interpreted using a nucleation dissolution-mediated recrystallization mechanism. The fabricated FZONSs may provide potential in various applications including advanced catalysts, sensing devices, and solar cells.

Insight into the Potential Antioxidant and Antidiabetic Activities of Scrolled Kaolinite Single Sheet (KNs) and Its Composite with ZnO Nanoparticles: Synergetic Studies

The kaolinite sheets were scrolled by sonication-induced chemical delamination processes into well-developed nanotubes (KNs) which were used as substrates for microwave-based ZnO nanoparticles (ZnO/KNs). The biological activities of synthetic ZnO/KNs structures, in terms of the antioxidant and antidiabetic properties, were assessed in comparative studies with the separated phases of the synthetic ZnO and KNs as well as the commercially used ZnO. The KNs substrate resulted in a notable enhancement in the antioxidant and antidiabetic properties of ZnO, which was assigned positive influence on the surface area, interactive interfaces, charge separation, and agglomeration properties of ZnO in addition to the detectable bioactive properties of the KNs structure. The ZnO/KNs structure achieved remarkable scavenging efficiencies for 1, 1-diphenyl-2-picrylhydrazil (DPPH) (89.8 ± 1.57%), nitric oxide (90.6 ± 1.63%), 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) (86.8 ± 1.28%), and superoxide (43.9 ± 1.72%) radicals. Additionally, it shows high inhibition effects on porcine α-amylase (84.3 ± 1.92%), crude α-amylase (70.6 ± 1.37%), pancreatic α-Glucosidase (94.7 ± 1.54%), crude α-Glucosidase (95.4 ± 1.64%), and amyloglucosidase (95.3 ± 1.32%) enzymes. This antidiabetic activity is significantly higher than the activity of miglitol and close to or slightly higher than acarbose, which leads us to recommend the use of ZnO/KNs when considering the cost and side effects of the commercially used drugs.

Green engineered synthesis of PbxZn1-xO NPs: An efficient electrochemical sensor and UV light-driven photocatalytic applications

The present work deals with preparation of PbxZn1-xO nanoparticles (NPs) (x = 0, 0.1, 0.3 & 0.5 M) first time using Zingiber officinale leaf as green fuel by solution combustion route and its structural confirmation was achieved by different spectral techniques. Powder-X-ray diffraction (P-XRD) analysis confirmed the switching of dopant Pb ions into host lattice without altering hexagonal wurtzite phase of host ZnO. The impact of Pb dopant directly affects crystallinity of ZnO host lattice changes the surface morphology with noticeable voids and pores with agglomeration examined by Scanning Electron Microscopy (SEM). The decreasing energy band gap of prepared nanoparticles from 3.3 eV − 2.4 eV due to increasing Pb content examined by UV–Visible absorption spectral technique hinders the recombination of electron-holes pairs by trapping e- and h+, which influence the enhanced photocatalytic activities. This optical characterization influences the achieved NPs used as excellent photocatalyst to remove malachite green (MG) dye under visible-light irradiation, which shows 98.5 % dye degradation at 160 min confirmed by its low kinetic constants of photocatalytic degradation of MG dye for Pb doped ZnO (17.42x10-3 min−1) than host ZnO (10.82×10-3 min−1) nanoparticles. The thermodynamics of redox reaction and capacitance measurement of prepared NPs-graphite paste electrode was investigated by electrochemical analysis in a 3-electrode system using 0.1 M KCl in the different scan rates 0.01–0.05 V/s. The excellent variation of redox peak potentials performance on sensor detections, the Pb-ZnO NPS shows an excellent chemical (Paracetamol) and biomolecule (Dextrose) sensing activity due to the region of Pb+2 ions effect.

Role of Zn-Al oxide structure and oxygen vacancy in bifunctional catalyst for syngas conversion to light olefins

Metal oxide plays a vital role in bifunctional tandem-catalyzed CO hydrogenation to light olefins. Herein, a series of Zn-Al metal oxides were prepared and then physically mixed with SAPO-18, the prepared bifunctional catalyst was applied in direct conversion of syngas to light olefins. The effects of structure and oxygen vacancy of Zn-Al oxide were studied by changing the preparation method and the sequence of precipitation. The sequential-precipitated ZA-SP oxide exhibits the ZnAl2O4 spinel structure and no obvious crystalline phase of γ-Al2O3 or ZnO. Compared with the reverse- or co-precipitated or the impregnated Zn-Al oxides, ZA-SP oxide possesses the highest oxygen vacancy content and amounts of desorbed CO, which facilitates the CO adsorption and activation. The adsorbed and activated CO on the surface of Zn-Al oxide converted to *CH3O intermediates with the dissociated H species on −Zn−O− sites, and then formed reaction intermediates as in methanol to olefins reaction. After optimizing the calcination temperature of ZA-SP oxide, weight ratio of ZA-SP to SAPO-18, reaction temperature, and gas hourly space velocity, the ZA-SP/SAPO-18 bifunctional catalyst exhibits the highest light olefins space time yield of 10.0 mmol·gcat−1·h−1 at a CO conversion of 40.2 %, which outperforms the previous reported values.