Deposition and Characterisation of Nitrogen-Doped Zinc Oxide Thin Films by MOCVD Using Zinc Acetate—Ammonium Acetate Precursor

The synthesis and comprehensive analysis of nitrogen-doped zinc oxide thin films grown from a compound precursor of zinc acetate and ammonium acetate has been reported. The precursor was processed in different ratios of the zinc acetate-ammonium acetate additives, and each combination was used to deposit a thin film using metalorganic chemical vapour deposition (MOCVD) method. The produced thin films were characterised using Rutherford backscattering (RBS) spectroscopy, uv-visible spectrometry, x-ray diffractometry, four point probe measurements and optical microscopy. The deposited thin films showed a fairly consistent zinc:oxygen:nitrogen ratio of 4.4:3.7:1, the film structures were quasicrystalline and the sheet resistivities were high, while other familiar characteristics like optical transmittance, bandgap, thermal stability, etc. were maintained in the grown films. Applications in device fabrication and active sensor devices were hence envisaged as the emergent potentials of the thin films.

Dietary supplementation of zinc oxide modulates intestinal functionality during the post-weaning period in clinically healthy piglets

Background To improve our understanding of host and intestinal microbiome interaction,this research investigated the effects of a high-level zinc oxide in the diet as model intervention on the intestinal microbiome and small intestinal functionality in clinically healthy post-weaning piglets.In study 1,piglets received either a high concentration of zinc(Zn)as zinc oxide(Zn O,Zn,2,690 mg/kg)or a low Zn concentration(100 mg/kg)in the diet during the post weaning period(d 14–23).The effects on the piglet's small intestinal microbiome and functionality of intestinal tissue were investigated.In study 2,the impact of timing of the dietary zinc intervention was investigated,i.e.,between d 0–14 and/or d 14–23 post weaning,and the consecutive effects on the piglet's intestinal functionality,here referring to microbiota composition and diversity and gene expression profiles.Results Differences in the small intestinal functionality were observed during the post weaning period between piglets receiving a diet with a low or high concentration Zn O content.A shift in the microbiota composition in the small intestine was observed that could be characterized as a non-pathological change,where mainly the commensals inter-changed.In the immediate post weaning period,i.e.,d 0–14,the highest number of differentially expressed genes(DEGs)in intestinal tissue were observed between animals receiving a diet with a low or high concentration Zn O content,i.e.,23 DEGs in jejunal tissue and 11 DEGs in ileal tissue.These genes are involved in biological processes related to immunity and inflammatory responses.For example,genes CD59 and REG3G were downregulated in the animals receiving a diet with a high concentration Zn O content compared to low Zn O content in both jejunum and ileum tissue.In the second study,a similar result was obtained regarding the expression of genes in intestinal tissue related to immune pathways when comparing piglets receiving a diet with a high concentration Zn O content compared to low Zn O content.Conclusions Supplementing a diet with a pharmaceutical level of Zn as Zn O for clinically healthy post weaning piglets influences various aspects intestinal functionality,in particular in the first two weeks post-weaning.The model intervention increased both the alpha diversity of the intestinal microbiome and the expression of a limited number of genes linked to the local immune system in intestinal tissue.The effects do not seem related to a direct antimicrobial effect of Zn O.

Nanocomposite superstructure of zinc oxide mesocrystal/reduced graphene oxide with effective photoconductivity

Metal oxide mesocrystals are the alignment of metal oxide nanoparticles building blocks into the ordered superstructure,which have potentially tunable optical,electronic,and electrical properties suitable for practical applications.Herein,we report an effective method for synthesizing mesocrystal zinc oxide nanorods(ZnONRs).The crystal,surface,and internal structures of the zinc oxide mesocrystals were fully characterized.Mesocrystal zinc oxide nanorods/reduced graphene oxide(ZnONRs/rGO)nanocomposite superstructure were synthesized also using the hydrothermal method.The crystal,surface,chemical,and internal structures of the ZnONRs/rGO nanocomposite superstructure were also fully characterized.The optical absorption coefficient,bandgap energy,band structure,and electrical conductivity of the ZnONRs/rGO nanocomposite superstructure were investigated to understand its optoelectronic and electrical properties.Finally,the photoconductivity of the ZnONRs/rGO nanocomposite superstructure was explored to find the possibilities of using this nanocomposite superstructure for ultraviolet(UV)photodetection applications.Finally,we concluded that the ZnONRs/rGO nanocomposite superstructure has high UV sensitivity and is suitable for UV detector applications.

Revealing the role of calcium ion intercalation of hydrated vanadium oxides for aqueous zinc-ion batteries

Exploring suitable high-capacity V_(2)O_(5)-based cathode materials is essential for the rapid advancement of aqueous zinc ion batteries(ZIBs).However,the typical problem of slow Zn^(2+)diffusion kinetics has severely limited the feasibility of such materials.In this work,unique hydrated vanadates(CaVO,BaVO)were obtained by intercalation of Ca^(2+)or Ba^(2+)into hydrated vanadium pentoxide.In the CaVO//Zn and BaVO//Zn batteries systems,the former delivered up to a 489.8 mAh g^(-1)discharge specific capacity at 0.1 A g^(-1).Moreover,the remarkable energy density of 370.07 Wh kg^(-1)and favorable cycling stability yard outperform BaVO,pure V_(2)O_(5),and many reported cathodes of similar ionic intercalation compounds.In addition,pseudocapacitance analysis,galvanostatic intermittent titration(GITT)tests,and Trasatti analysis revealed the high capacitance contribution and Zn^(2+)diffusion coefficient of CaVO,while an in-depth investigation based on EIS elucidated the reasons for the better electrochemical performance of CaVO.Notably,ex-situ XRD,XPS,and TEM tests further demonstrated the Zn^(2+)insertion/extraction and Zn-storage mechanism that occurred during the cycle in the CaVO//Zn battery system.This work provides new insights into the intercalation of similar divalent cations in vanadium oxides and offers new solutions for designing cathodes for high-capacity aqueous ZIBs.

Synergism of Zinc Oxide/Organoclay-Loaded Poly(lactic acid) Hybrid Nanocomposite Plasticized by Triacetin for Sustainable Active Food Packaging

The synergistic effect of organoclay(OC)and zinc oxide(ZnO)nanoparticles on the crucial properties of poly(lactic acid)(PLA)nanocompositefilms was systematically investigated herein.After their incorporation into PLA via the solvent casting technique,the water vapor barrier property of the PLA/OC/ZnOfilm improved by a maximum of 86%compared to the neat PLAfilm without the deterioration of Young’s modulus or the tensile strength.Moreover,thefilm’s self-antibacterial activity against foodborne pathogens,including gram-negative(Escherichia coli,E.coli)and gram-positive(Staphylococcus aureus,S.aureus)bacteria,was enhanced by a max-imum of approximately 98–99%compared to the neat PLAfilm.Furthermore,SEM images revealed the homo-geneous dispersion of both nano-fillers in the PLA matrix.However,the thermal stability of thefilm decreased slightly after the addition of the OC and ZnO.Thefilm exhibited notable light barrier properties in the UV-Vis range.Moreover,the incorporation of a suitable biodegradable plasticizer significantly decreased the Tg and notably enhanced theflexibility of the nanocompositefilm by increasing the elongation at break approxi-mately 1.5-fold compared to that of the neat PLAfilm.This contributes to its feasibility as an active food packa-ging material.

Unveiling the synthesis,characteristics,electrical conductivity,photocatalytic activity,and electrochemical activity of eco-friendly zinc oxide nanoparticles

The Nigella Sativa seeds were utilized for the environment-friendly zinc oxide nanoparticles(ZnO NPs),as evident by the observation of a white precipitate.Numerous analytical techniques,such as XRD,FTIR,UV–vis,SEM,and EDX,were utilized to describe the specimen's structural,optical,and electrical properties.XRD analysis was used to confirm that the ZnO NPs were crystalline.An absorbance peak at 401 nm was observed in the UV–vis,indicating that the ZnO NPs have a 2.91 eV bandgap.Functional groups are present in ZnO NPs,as seen by the FTIR graph.The nanoparticles'spherical form and average size of 37.9 nm were confirmed by the SEM image.EDX analysis confirmed the composition of the nanoparticles,with zinc accounting for 73.17%and oxygen for 26.83%.ZnO NPs demonstrated excellent electrical conductivity because of their higher surface-to-volume ratio.Additionally,the synthesis of ZnO NPs exhibited effective degradation of methylene blue dye.These results point to potential applications in several domains,including electronics,biomedical devices,industry,and agriculture,and they call for immediate follow-up research.

Hollow cobalt oxide nanoparticles embedded in nitrogen-doped carbon nanosheets as an efficient bifunctional catalyst for Zn–air battery

Rational design of low-cost, highly electrocatalytic activity, and stable bifunctional electrocatalysts for oxygen reduction reaction(ORR) and oxygen evolution reaction(OER) has been a great significant for metal–air batteries. Herein, an efficient bifunctional electrocatalyst based on hollow cobalt oxide nanoparticles embedded in nitrogen-doped carbon nanosheets(Co/N-Pg) is fabricated for Zn–air batteries. A lowcost biomass peach gum, consisting of carbon, oxygen, and hydrogen without other heteroatoms, was used as carbon source to form carbon matrix hosting hollow cobalt oxide nanoparticles. Meanwhile, the melamine was applied as nitrogen source and template precursor, which can convert to carbon-based template graphitic carbon nitride by polycondensation process. Owing to the unique structure and synergistic effect between hollow cobalt oxide nanoparticles and Co-N-C species, the proposal Co/N-Pg catalyst displays not only prominent bifunctional electrocatalytic activities for ORR and OER, but also excellent durability. Remarkably, the assembled Zn–air battery with Co/N-Pg air electrode exhibited a low discharge-charge voltage gap(0.81 V at 50 mA cm^-2) and high peak power density(119 mW cm^-2) with long-term cycling stability. This work presents an effective approach for engineering transition metal oxides and nitrogen modified carbon nanosheets to boost the performance of bifunctional electrocatalysts for Zn–air battery.

Robust copper nanocrystal/nitrogen-doped carbon monoliths as carbon monoxide-resistant electrodes for methanol oxidation reaction

Noble metal-based electrocatalysts present high activities for methanol oxidation reaction(MOR),but are limited by their high cost,low stability and poor resistance to carbon monoxide(CO) poisoning.The development of active and stable non-noble metal electrocatalysts for MOR is desired,but remains a challenge.Herein,we report a simple strategy to make copper nanocrystal/nitrogen-doped carbon(Cu/N-C)monoliths,which can serve as active and robust electrodes for MOR.Copper nanocrystals were electrochemically deposited onto a conductive polyaniline hydrogel and calcined to form Cu/N-C monolith,where the active copper nanocrystals are protected by nitrogen-doped carbon.Owing to their extremely high electrical conductivity(1.25 × 10^(5) S cm^(-1)) and mechanical robustness,these Cu/N-C monoliths can be directly used as electrodes for MOR,without using substrates or additives.The optimal Cu/N-C(FT)@500 monolith shows a high MOR activity of 189 mA cm^(-2) at 0.6 V vs.SCE in alkaline methanol solution,superior to most of reported Cu-based MOR catalysts.Cu/N-C(FT)@500 also presents a better stability than Pt/C catalyst in the long-term MOR test at high current densities.Upon carbon monoxide(CO) poisoning,Cu/N-C(FT)@500 retains 96% of its MOR activity,far exceeding the performance of Pt/C catalyst(61% retention).Owing to its facile synthesis,outstanding activity,high stability and mechanical robustness,Cu/N-C(FT)@500 monolith is promising as a low-cost,efficient and CO-resistant electrocatalyst for MOR.

Metal Oxide/Nitrogen-Doped Carbon Catalysts Enables Highly Effi cient CO_(2) Electroreduction

The metal oxide/nitrogen-doped carbon(NC)compounds zirconium oxide/NC(ZrO_(2)/NC)and cerium oxide/NC(CeO_(2)/NC)were synthesized via the pyrolysis of polyaniline on the metal oxide surface.The characterization of the ZrO_(2)/NC and CeO_(2)/NC catalysts showed more active CO_(2) reduction reaction activity than that of NC catalyst without metal oxide.Gas chromatography analysis revealed that CO and H_(2)were the primary products,and no liquid-phase products were detected via proton nuclear magnetic resonance spectroscopy or high-performance liquid chromatography.The maximum Faraday effi ciency of ZrO_(2)/NC reached 90%at−0.73 V(vs.RHE),with the current density of CO at 5.5 mA/cm^(2);this Faraday effi ciency value was higher than that of NC(41%),with the current density of CO at 3.1 mA/cm^(2).The interaction between the metal oxide and carbon allowed the effi cient formation of defect sites,especially imine-type nitrogen,strengthening the adsorption of the key reaction intermediate CO_(2)^(•−) and thus promoting the CO_(2) reduction reaction.

Enhanced visible-light photocatalytic activity of Z-scheme graphitic carbon nitride/oxygen vacancy-rich zinc oxide hybrid photocatalysts

With the objectives of enhancing the stability,optical properties and visible-light photocatalytic activity of photocatalysts,we modified oxygen vacancy-rich zinc oxide（Vo-ZnO） with graphitic carbon nitride（g-C3N4）. The resulting g-C3N4/Vo-ZnO hybrid photocatalysts showed higher visible-light photocatalytic activity than pure Vo-ZnO and g-C3N4. The hybrid photocatalyst with a g-C3N4 content of 1 wt% exhibited the highest photocatalytic degradation activity under visible-light irradiation（λ≥ 400 nm）. In addition,the g-C3N4/Vo-ZnO photocatalyst was not deactivated after five cycles of methyl orange degradation,indicating that it is stable under light irradiation. Finally,a Z-scheme mechanism for the enhanced photocatalytic activity and stability of the g-C3N4/Vo-ZnO hybrid photocatalyst was proposed. The fast charge separation and transport within the g-C3N4/Vo-ZnO hybrid photocatalyst were attributed as the origins of its enhanced photocatalytic performance.

Mechano-chemical sulfidization of zinc oxide by grinding with sulfur and reductive additives

A novel process for sulfidation of ZnO by co-grinding with sulfur and reductive additives （P, Fe, A1, and Mg） was developed. The sulfidation extent of ZnO with the addition of P, Fe, A1 or Mg can reach 85.2%, 81.6%, 96.7% and 92.6% after grinding for 4, 6, 1 and 1 h, respectively. Based on the chemical phase composition analysis and morphological characteristics of sulfidized products by XRD, SEM and TEM, a possible reaction mechanism, mechanically induced self-propagating reaction （MSR）, was proposed to explain the sulfidization reaction. In addition, the floatability of sulfidized products was investigated for the recovery of metal sulfide and ZnS can be concentrated with a high concentration ratio and concentrate grade. By using the sulfidizing process, it is expected that the recovery of zinc from the wastes or purification of heavy-metal-containing hazardous residues is technically feasible.

Determination of arsenic speciation in secondary zinc oxide and arsenic leachability

The species of arsenic in secondary zinc oxide generated from fuming furnace were investigated. The results revealed that there are mainly three types of secondary zinc oxide based on three arsenic species. The main phase of As is As2O3 in type Ⅰ, zinc arsenite （Zn（AsO2）2） in type Ⅱ and lead arsenate （Pb（As206）, Pb4As2O9） in type Ⅲ, respectively. Selective leaching of zinc oxide of type Ⅱ was carried out. The leaching rate of As kept at 65%-70% with 30 g/L NaOH and L/S ratio of 3 at 20 ℃ for 1 h, while the losses of Pb and Zn were both below 1%.

Leaching of low grade zinc oxide ores in Ida^(2-)-H_2O system

Ida2--H2O system（iminodiacetate aqueous solution） was used to leach a low grade zinc oxide ore for Zn extraction.The effects of leaching time,liquid-solid ratio（L/S）,total concentration of Ida2-（[Ida2-]T）,leaching temperature and pH on Zn leaching recovery and the dissolution of impurities such as Ca,Mg,Cu,Ni,Fe,Pb and Cd were investigated.Results show that Ca,Mg and Fe in ores were hardly dissolved in alkalescent iminodiacetate aqueous solution,while valuable metals such as Cu,Ni,Pb and Cd were partly dissolved into leaching liquor with Zn.The recovery of Zn reaches 76.6% when the ores were leached for 4 h at 70 ℃ by 0.9 mol/L iminodiacetate aqueous solution with pH of 8 and L/S of 5：1.

Selective recovery of lead from zinc oxide dust with alkaline Na_2EDTA solution

The selective recovery of lead from the zinc oxide dust using an alkaline Na2EDTA solution was investigated. The effects of temperature, leaching time, Na2EDTA concentration and initial NaOH concentration on the leaching rates of lead and zinc were studied. The following optimized leaching conditions were obtained： liquid-to-solid ratio 5：1 mL/g, stirring speed 650 r/min, Na2EDTA concentration 0.12 mol/L, initial NaOH concentration 0.5 mol/L, leaching temperature 70 ℃, leaching time 120 min. Under the optimized conditions, the average leaching rates of lead, zinc, fluoride and chloride are 89.92%, 0.94%, 62.84% and 90.02%, respectively. The filtrate was used to electrowin lead powders. The average current efficiency of electrowinning is about 93% and lead content is higher than 98% under the conditions of temperature of 60 ℃, current density of 200 A/m2, H3PO4 concentration of 1.5 g/L, and lead ion concentration of above 5 g/L. The consumption of Na2EDTA and the direct current are about respectively 0.218 kg and 0.958 kW·h for per kilogram of lead powder.

Response surface optimization of process parameters for removal of F and Cl from zinc oxide fume by microwave roasting

Microwave was applied to roasting the zinc oxide fume obtained from fuming furnace for the removal of F and Cl. The effects of important parameters, such as roasting temperature, holding time and stirring speed, were investigated and the process conditions were optimized using response surface methodology (RSM). The results show that the effects of roasting temperature and holding time on the removal rate of F and Cl are the most significant, and the effect of stirring speed is the second. The defluorination rate reaches 92.6% while the dechlorination rate reaches 90.2%, under the process conditions of roasting temperature of 700 °C, holding time of 80 min and stirring speed of 120 r/min. The results indicate that the removal of F and Cl from fuming furnace production of zinc oxide fumes using microwave roasting process is feasible and reliable.

Dielectric properties and temperature increase characteristics of zinc oxide dust from fuming furnace

Cavity perturbation method was used to determine the dielectric properties （ε′,ε″, and tanδ） of zinc oxide dust in different apparent densities. The process was conducted to study the microwave-absorption properties of zinc oxide dust and the feasibility of microwave roasting zinc oxide dust to remove fluorine and chlorine. The dielectric constant, dielectric loss, and loss tangent were proportional to the apparent density of zinc oxide dust. The effects of sample mass and microwave power on the temperature increase characteristics under the microwave field were also studied. The results show that the apparent heating rate of the zinc oxide dust increases with the increase in microwave roasting power and decreases with the increase in the sample mass. The temperature of the samples reaches approximately 800 ＆#176;C after microwave treatment for 8 min, which indicates that the zinc oxide dust has strong microwave-absorption ability.

Stable zinc oxide field emitter-based backlight unit for liquid crystal display

A zinc oxide ZnO field emitter-based backlight unit for liquid crystal display with a gated structure is fabricated by screen-printing processes.The measured anode field emission current density reaches 0.62 mA/cm2 when the applied gate voltage is 570 V.Part of the anode current is contributed by the secondary electron emission which is excited from the MgO layer inside the gate apertures on the gate plate. The average emission current density and luminance are 0.47 mA/cm2 and 1 250 cd/m2 respectively with a fluctuation of about 10% during the 1 000 min measurement.By a finite element method calculation the gated structure shows a good electron beam focusing property. The driving performance of the backlight unit is characterized by SPICE simulation tools and measured by the oscilloscope. Stable field emission line-by-line scanning and fast response characteristics of the backlight unit indicate its promising application in the liquid crystal displays.

Synthesis and characterization of LiFePO_4 coating with aluminum doped zinc oxide

Aluminum doped zinc oxide （AZO）, as an electrically conductive material, was applied to coating on the surface of olivine-type LiFePO4 synthesized by solid-state method. The charge-discharge test results show that the rate performance and low-temperature performance of LiFePO4 are greatly improved by the surface treatment. Even at 20C rate, the discharge specific capacity of 100.9 mA.h/g was obtained by the AZO-coated LiFePO4 at room temperature. At -20 ℃, the discharge specific capacity at 0.2C for un-coated LiFePO4 and the coated one are 50.3 mA.h/g and 119.4 mA.h/g, respectively. It should be attributed to the electrically conductive AZO-coating which increases the electronic conductivity of LiFePO4. Furthermore, the surface-coating increases the tap-density of LiFePO4. The results indicate that the AZO-coated LiFePO4 is a good candidate of cathode material for applying in lithium power batteries.

Effect of RF power on the properties of transparent conducting zirconium-doped zinc oxide films prepared by RF magnetron sputtering

Transparent and conducting zirconium-doped zinc oxide films with high transparency and relatively low resistivity have been successfully prepared by radio frequency （RF） msgnetron sputtering at room temperature, The RF power is varied from 75 to 150 W. At first the crystallinity and conductivity of the film are improved and then both of them show deterioration with the increase of the RF power, The lowest resistivity achieved is 2.07 × 10^-3Ωcm at an RF power of 100W with a Hall mobility of 16cm^2V^-1s^-1 and a carrier concentration of 1.95 × 10^20 cm^-3. The films obtained are polycryetalline with a hexagonal structure and a preferred orientation along the c-axis, All the films have a high transmittance of approximately 92% in the visible range. The optical band gap is about 3.33 eV for the films deposited at different RF powers.

Microbial synthesis of zinc oxide nanoparticles and their potential application as an antimicrobial agent and a feed supplement in animal industry: a review

In recent years, zinc oxide nanoparticles(ZnO NPs) have gained tremendous attention attributed to their unique properties. Notably, evidence has shown that zinc is an important nutrient in living organisms. As such, both prokaryotes and eukaryotes including bacteria, fungi and yeast are exploited for the synthesis of ZnO NPs by using microbial cells or enzyme, protein and other biomolecules compounds in either an intracellular or extracellular route. ZnO NPs exhibit antimicrobial properties, however, the properties of nanoparticles(NPs) are depended upon on their size and shape, which make them specific for various applications. Nevertheless, the desired size and shape of NPs can be obtained through the optimization process of microbes mediated synthesis by manipulating their reaction conditions. It should be noted that ZnO NPs are synthesized by various chemical and physical methods.Nonetheless, these methods are expensive and not environmentally friendly. On that account, the microbes mediated synthesis of ZnO NPs have rapidly evolved recently where the microbes are cleaner, eco-friendly, nontoxic and biocompatible as the alternatives to chemical and physical practices. Moreover, zinc in the form of NPs is more effective than their bulk counterparts and thus, they have been explored for many potential applications including in animals industry. Notably, with the advent of multi-drug resistant strains, ZnO NPs have emerged as the potential antimicrobial agents. This is mainly due to their superior properties in combating a broad spectrum of pathogens. Moreover, zinc is known as an essential trace element for most of the biological function in the animal’s body. As such, the applications of ZnO NPs have been reported to significantly enhance the health and production of the farm animals. Thus, this paper reviews the biological synthesis of ZnO NPs by the microbes, the mechanisms of the biological synthesis, parameters for the optimization process and their potential application as an antimicrobial agent and feed supplement in the animal industry as well as their toxicological hazards on animals.