Nanoscale Zinc Oxide Research Articles

Method for Surface Characterization Using Solid-State Nuclear Magnetic Resonance Spectroscopy Demonstrated on Nanocrystalline ZnO:Al.

Nanoscale zinc-oxide doped with aluminum ZnO:Al is studied by different techniques targeting surface changes induced by the conditions at which ZnO:Al is used as support material in the catalysis of methanol. While it is well established that a variety of 1H and 27Al resonances can be found by solid-state NMR for this material, it was not clear yet which signals are related to species located close to the surface of the material and which to species located in the bulk. To this end, a method is suggested that makes use of a paramagnetically impregnated material to suppress NMR signals close to the particle surface in the blind sphere around the paramagnetic metal atoms. It is shown that it is important to use conditions that guarantee a stable reference system relative to which it can be established whether the coating procedure is conserving the original structure or not. This method, called paramagnetically assisted surface peak assignment, helped to assign the 1H and 27Al NMR peaks to the bulk and the surface layer defined by the blind sphere of the paramagnetic atoms. The assignment results are further corroborated by the results from heteronuclear 27Al{1H} dipolar dephasing experiments, which indicate that the hydrogen atoms are preferentially located in the surface layer and not in the particle core.

Synthesis of Zinc Oxide Nanoflakes by Non-Thermal Plasma Technique and Evaluation of Anticancer Activity in Vitro

This paper describes the synthesis of ZnO nanoparticles using air microplasma jets as the main reaction medium. Various techniques, including X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and UV—Vis spectroscopy, were employed to confirm the characterization of the artificially synthesized ZnO nanoparticles. The absence of additional peaks associated with secondary phases of ZnO, as revealed by the XRD analysis, indicates the exceptional purity of these nanoparticles. Through the use of SEM, we examined the surface morphology and observed a substantial rate of agglomeration. The energy band gaps of ZnO nanoparticles were determined to be 3.3 electron volts (eV). The cytotoxic effects of zinc oxide nanoparticles were assessed using the methyl thiazolyl tetrazolium (MTT) assay on breast cancer cells exposed to various doses of the nanoparticles. The Acridine-Orange/Ethidium-bromide (AO/EB) dual stain was employed to assess apoptotic cells. The data indicate that ZnO NPs can induce apoptosis, suggesting their potential as an anticancer treatment in breast cancer cell lines. The presented findings indicate that nanoscale zinc oxide particles (ZnO NPs) possess significant potential for future utilization in many biological applications. An example of such an application could be the prospective substitution for chemotherapy in the management of various forms of cancer diseases.

Assessing the Chemical and Biological Effectiveness of Nano-Engineered Factors in Enhancing Resistance in tomato against Xanthomonas campestris pv. vesicatoria

Bacterial spot a significant disease that affects tomato crops, despite limited studies and scientific research on this disease, So This study aimed to assess the efficacy of various biological and chemical factors in controlling bacterial spot disease in the field. A field survey was conducted in Najaf Al-Ashraf, specifically in areas such as Al-Haidariya, Al-Rahima, Al-Abbasia, and 20 plastic houses. The disease incidence was observed in these locations, with infection rates from 24% to 60%. Among them, Al-Haidariya had the highest infection rate at 60%, while Al-Abbasia had the lowest at 24%. Regarding to the impact of chemical and biological inducing factors on infection severity, the treatment using nanoscale zinc oxide demonstrated superior effectiveness in reducing the severity of infection caused by Xanthomonas campestris pv. vesicatoria, In reducing the severity of the infection, which amounted to 11.6%, compared with the treatment of X.campestris 2 (control 2) only, which amounted to 74.2%.Field results also indicated that the nanoscale zinc oxide treatment was highly effective in increasing chemical indicators such as chlorophyll content, peroxidase enzyme and catalase enzyme. The values for these indicators were 12.69 mg g-1, 183.25-unit min-1 g-1 FW and 177.84-unit min-1 g-1 FW, respectively, compared to the control treatment, which recorded values of 7.79 mg g-1, 88.3-unit min-1 g-1 FW, and 74.17-unit min-1 g-1 FW, respectively. Furthermore, the treatment using Pseudomonas putida demonstrated superiority in increasing the percentage of TSS, vitamin C content, and acid percentage. The values for these parameters were 8.45%, 20.86 mg g-1, and 0.862%, respectively, compared to the control treatment, which recorded values of 4.78%, 11.09 mg g-1 and 0.462%, respectively. Moreover, the nanoscale zinc oxide treatment exhibited superior effectiveness in increasing the yield per plant, early fruit yield per plant, and total yield. The values for these parameters were 7.54 kg plant-1, 10.261 kg. plant-1 and 8.591 tons plastichouse-1 (500 m²), respectively, compared to the control treatment, which recorded values of 4.15 kg plant-1, 3.752 kg plant-1, and 4.929 tons/plastic house (500 m²), respectively.

Molecular dynamics simulation of mechanical and thermal properties of nano-zinc oxide modified cellulose insulating paper

With the surge in electrical loads and increasing voltage levels, the mechanical performance and thermal stability of insulating paper are facing severe challenges. However, due to the lack of direct scientific theories or simulation guidance, traditional inefficient “trial-and-error” experiments are difficult to effectively develop new types of cellulose composite insulating papers. For solving this problem, in this work we are to enhance the effects of nanoscale zinc oxide (nano-ZnO) on the mechanical and thermal properties of cellulose through molecular dynamics simulations. Initially, we model the nano-ZnO/cellulose composite material , then carry out a microscopic analysis of the mechanical performance and thermal stability of modified cellulose with varying nano-ZnO content, thus determining the optimal ratio of nano-ZnO to cellulose. The results indicate that compared with the outcomes from the unmodified model, the mechanical performance, cohesive energy density, glass transition temperature, and thermal conductivity of the nano-ZnO-modified cellulose model are all improved, with the highest increase in elastic modulus reaching 45.31% and the highest increase in thermal conductivity attaining 41.49%. The addition of nano-ZnO effectively fills the gaps in the fiber network and enhances the interactions between cellulose chains and thermal conduction channels, thereby improving the thermodynamic performance of cellulose. This work provides valuable theoretical references for rapidly preparing modified cellulose insulating papers with excellent thermodynamic performance.

Ligand-based magnetic extraction and safety assessment of zinc oxide nanoparticles in food products

Zinc oxide (ZnO) is a zinc supplement widely used in health products and is approved by the FDA as Generally Regarded as Safe (GRAS). However, concerns have arisen regarding the potential health effects of nanoscale ZnO, as its reactivity differs from that of its bulk form. This has led to the need for an efficient method to extract ZnO from food products without altering its physicochemical properties, where conventional methods have proven to be inadequate. This study introduces an innovative approach using starch magnetic particles (SMPs) functionalized with a 12-amino acid peptide modified with five lysines (ZBP), that has specific affinity to ZnO. ZBP@SMPs effectively and rapidly extract intact ZnO from food products, achieving recovery efficiencies ranging from 60% to 90%, all while maintaining its morphology and crystallinity. The diameter of ZnO particles recovered from six commercial food products ranged from 25 to 500 nm, with 33% falling below 100 nm, highlighting the need for a size-dependent toxicity study. However, cytotoxicity assessment on human intestinal Caco-2 cells shows all ZnO samples affects cell proliferation and membrane integrity in a dose-dependent manner due to partial dissolution. This study contributes to understanding the safety of ZnO-containing food products and highlights potential health implications associated with their consumption.

Synthesis of Zinc Oxide Doped Magnesium Hydrate and Its Effect on the Flame Retardant and Mechanical Properties of Polypropylene.

In this work, an effective flame retardant consisting of nanoscale zinc oxide doped on the surface of hexagonal lamellar magnesium hydrate (ZO@MH) has been successfully synthesized via a hydrothermal process. Approximately 3-methacryloxypropyltrimethoxysilane (KH-570) is chosen as a modifier of ZO@MH for the purpose of enhancing the interfacial interaction between ZO@MH and the polypropylene (PP) matrix and reducing the agglomeration of ZO@MH. Afterwards, ZO@MH and KH-570 modified ZO@MH (KZO@MH) filled PP (PP/ZO@MH and PP/KZO@MH) composites are respectively prepared via the melt blending method. The flame retardant and smoke suppression properties of PP/ZO@MH and PP/KZO@MH composites are estimated by a cone calorimetry test (CCT). The peak value of the heat release rate of the PP/40KZO@MH composite is 327.0 kW/m2, which is 6.1% and 31.2% lower than that of the PP/40ZO@MH and PP/40MH composites, respectively. The lowest peak values of CO and CO2 production, 0.008 and 0.62 g/s, also appeared in the PP/40KZO@MH composite, which are 11.1% and 10.1% lower than those of the PP/40ZO@MH composite. Analysis of char residues indicates that nanoscale ZO and modification of KH-570 improve the amount and quality of char residues, which should be the main reason for the good flame retardant and smoke suppression properties of KZO@MH. Impact strength and nominal strain at break results show that the PP matrix is toughened by ZO@MH rather than KZO@MH. Tensile properties and the quantitative interfacial interaction calculated by the Turcsányi equation both prove the reinforcement of KZO@MH on the PP matrix.

Effects of nanoscale zinc oxide treatment on growth, rhizosphere microbiota, and metabolism of Aconitum carmichaelii.

Trace elements play a crucial role in the growth and bioactive substance content of medicinal plants, but their utilization efficiency in soil is often low. In this study, soil and Aconitum carmichaelii samples were collected and measured from 22 different locations, followed by an analysis of the relationship between trace elements and the yield and alkaloid content of the plants. The results indicated a significant positive correlation between zinc, trace elements in the soil, and the yield and alkaloid content of A. carmichaelii. Subsequent treatment of A. carmichaelii with both bulk zinc oxide (ZnO) and zinc oxide nanoparticles (ZnO NPs) demonstrated that the use of ZnO NPs significantly enhanced plant growth and monoester-type alkaloid content. To elucidate the underlying mechanisms responsible for these effects, metabolomic analysis was performed, resulting in the identification of 38 differentially expressed metabolites in eight metabolic pathways between the two treatments. Additionally, significant differences were observed in the rhizosphere bacterial communities, with Bacteroidota and Actinobacteriota identified as valuable biomarkers for ZnO NP treatment. Covariation analysis further revealed significant correlations between specific microbial communities and metabolite expression levels. These findings provide compelling evidence that nanoscale zinc exhibits much higher utilization efficiency compared to traditional zinc fertilizer.

Inorganic Nanoparticles–Driven Self–Assembly of natural small molecules in water for constructing multifunctional nanocapsules against plant diseases

Directly constructing nanoparticles through the self–assembly of natural small molecules in aqueous media presents many opportunities for crop protection; however, this special strategy is hindered by the lack of simple and cost–effective preparation methods to date. Herein, we report a facile strategy for constructing multifunctional natural nanocapsules for treating plant diseases based on the special coassembly of natural small organic molecules and inorganic nanoparticles. In aqueous conditions, uniform curcumin nanocapsules (ZnO@Cur) are assembled through electrostatic interactions, coordination effects and hydration effects as mediated by trace of nanoscale zinc oxide. The nanocapsules obtained can be further modified to enhance stability by introducing a polydopamine coating (ZnO@Cur@PDA). The antibacterial activity of ZnO@Cur@PDA against plant-pathogenic bacteria was better than that of curcumin, ZnO NPs, ZnO@Cur and zinc thiazole in vitro. The nanocapsules effectively kill plant–pathogenic bacteria via tight binding to the bacterial surface, inducing reactive oxygen species accumulation and disrupting bacterial cell walls. ZnO@Cur@PDA display strong activities against rice bacterial blight with protective activity of 64.0 % and curative activity of 62.2%, which is much better than commercial drugs bismerthiazol (protective activity of 33.0 % and curative activity of 38.4%) and zinc thiazole(protective activity of 38.6 % and curative activity of 31.8%). ZnO@Cur@PDA display adequate washing resistance, and low rice plant toxicity; furthermore, they are degradable. Additionally, both the inner cavities and outer surfaces of nanocapsules bear abundant sites and spaces that can be further tuned for loading other pesticide molecules or flexible construct complex multifunctional nanoparticles. Our study should encourage further development in the coassembly of organic and inorganic materials via green processes for effective and tunable nanopesticides.

Conjunctive and concentration dependent effects of nanoscale zinc and boron on the physiological, biochemical, nutrient uptake, and translocation processes in peanut (Arachis hypogaea L.)

In the present investigation, different concentrations (150, 200, 300, 400, and 500 mg/L) of nanoscale zinc oxide (ZnO) and boron (B) were applied through foliar spray (pot culture) to evaluate their effects on the growth and biochemical parameters of peanut. Nanoscale zinc oxide and nano boron were prepared using modified oxalate decomposition and encapsulation methods, respectively, and were characterized using techniques such as, X-ray diffraction (XRD), dynamic light scattering (DLS), ultraviolet–visible (UV–vis) spectroscopy, and transmission electron microscopy (TEM). The average size (37.2 nm, 53.6 nm) and zeta potential (−37.7 mV, −28.3 mV) of nano ZnO and nano boron were measured, respectively. Fourier transform infrared spectroscopic (FT-IR) studies revealed the functional groups that are present in the hydrosols. Highest germination percentage (98.7% and 96%), seedling vigor index (2359 and 1325) and total chlorophyll content (3.28 and 2.24 mg g−1) were recorded at 500 mg/L of nano zinc oxide and nano boron. Significantly higher peroxidase, catalase, superoxide dismutase (SOD) enzymatic activities, pod yield (39.76 g pot−1 and 38.14 g pot−1) and haulm yield (49.56 g pot−1 and 47.05 g pot−1) were also recorded with the application of nano ZnO and boron @ 500 mg/L. Translocation of nanoscale nutrients through stomata was clearly observed. Significant nutrient uptake with the foliar application of nanoscale nutrients has been recorded. The performance of groundnut (in terms of yield, quality and nutrient uptake) was significantly enhanced with the application of nanoscale nutrients and this point to achieving the nutrient bio-fortification with the desired levels for the betterment of human health.

Photoluminescent and magnetic characteristics of cobalt and manganese doped nanoscale zinc oxide

Photoluminescent and magnetic characteristics of cobalt and manganese doped nanoscale zinc oxide

Facet-dependent transformation and toxicity of nanoscale zinc oxide in the synthetic saliva

The nanoscale zinc oxide (n-ZnO) was used in food packages due to its superior antibacterial activity, resulting in potential intake of n-ZnO through the digestive system, wherein n-ZnO interacted with saliva. In recent, facet engineering, a technique for controlling the exposed facets, was applied to n-ZnO, whereas risk of n-ZnO with specific exposed facets in saliva was ignored. ZnO nanoflakes (ZnO-0001) and nanoneedles (ZnO-1010) with the primary exposed facets of {0001} and {1010} respectively were prepared in this study, investigating stability and toxicity of ZnO-0001 and ZnO-1010 in synthetic saliva. Both ZnO-0001 and ZnO-1010 partially transformed into amorphous Zn3(PO4)2 within 1 hr in the saliva even containing orgnaic components, forming a ZnO-Zn3(PO4)2 core-shell structure. Nevertheless, ZnO-1010 relative to ZnO-0001 would likely transform into Zn3(PO4)2, being attributed to superior dissolution of {1010} facet due to its lower vacancy formation energy (1.15 eV) than {0001} facet (3.90 eV). The toxicity of n-ZnO to Caco-2 cells was also dependent on the primary exposed facet; ZnO-0001 caused cell toxicity through oxidative stress, whereas ZnO-1010 resulted in lower cells viability than ZnO-0001 through oxidative stress and membrane damage. Density functional theory calculations illustrated that ·O2− was formed and released on {1010} facet, yet O22− instead of ·O2− was generated on {0001} facet, leading to low oxidative stress from ZnO-0001. All findings demonstrated that stability and toxicity of n-ZnO were dependent on the primary exposed facet, improving our understanding of health risk of nanomaterials.

Effect of Nanoscale Zinc Oxide Particles on Macronutrient Concentration of Groundnut (Arachis hypogaea L.)

In the present investigation, size dependent effects of nanoscale zinc oxide particulates (n-ZnO) on the macronutrient concentration of groundnut leaf, stem and kernel have been analysed. ZnO-nanoparticulates that were used in the study were prepared by modified oxalate decomposition method and the ZnO-nanoparticulates (mean size of 20, 25 and 30 nm) were characterized using techniques such as transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), Dynamic light scattering (DLS) and X-ray diffraction analysis (XRD). Different concentrations (150, 200 and 400 ppm) of ZnO-nanoparticulates were applied (foliar spray) to reveal their effects on groundnut crop in comparison to bulk ZnSO4 Statistically significant high kernel N content (0.49 %) was observed in n-ZnO of size 30 nm @ 400 ppm and highest P content in kernel (0.16 %) was observed in n- ZnO of size 30 nm @ 150 ppm. Whereas, highest kernel K content (0.7 %) was observed in both n-ZnO of size 25 nm and 30 nm @ 200 ppm. These results indicate that zinc nanoparticles significantly influenced the macronutrient (N, P, K) concentration of groundnut depending on their size and concentration.

Environmental Remediation via Solution Combustion Route Synthesis of Single-Phase Ferromagnetic Nickel Doped Zinc Oxide (Ni-ZnO) Nanostructure for Enhanced Photocatalytic Activity

To flourish new applications at a low cost to the environment, it is important to develop non-toxic eco-friendly ferromagnetic single-phase zinc oxide (ZnO) nanoparticles with nickel (Ni2+) doping. The titled materials were prepared using an easy and rapid solution combustion synthesis method. XRD, SEM, and TEM were used to figure out the structure and morphology of as-synthesized materials, which confirmed the nanoscale ZnO structure in a single phase. The sample shows a single phase with nickel metal incorporated into the Wurtzite crystal structure of ZnO by replacing the Zn2+. The ferromagnetic behavior of the as synthesized samples was observed at room temperature. The ferromagnetic exchange coupling between the doped Ni2+ ions facilitate the ferromagnetic behavior, and the magnetic saturation is increased with the Ni2+ doping. As-synthesized samples were shown to have photocatalytic activity. The incorporation of nickel ions in the ZnO structure facilitated the enhancement of the catalytic activity. The improved catalytic activity is attributed to the band gap tuning of the ZnO, which favors the improved degradation of the Methylene Blue dye under a UV light source. The prepared samples pave the way for recyclable photo-catalysis applications of ZnO, which can be easily separated using a permanent magnet.

Impact of Nanoscale Zinc Oxide Particle on the Growth, Yield and Soil Properties under Agency Area of Andhra Pradesh

Field experiment was carried out on silt clay loam soils at Regional Agricultural Research station, Chintapalle, Visakhapatnam, Andhra Pradesh during 2018-2020 to study the yield of response of rainfed groundnut with different levels of Nano particulate zinc oxide application along with NPK Fertilizers. The experiment consisting of eight treatments, three replications with RDF design. Results of nano particulate zinc oxide on pod yield showed that (24.36 Q/ha) in the RDF+ nano scale zinc oxide level @ 200 ppm at 25 and 45 DAS was increased over to that of normal recommended dose of N,P,K fertilizers (100% RDF) which recorded pod yield of 17.14 Q/ha only. Application of ZnSO4 through soil along with RDF showed good results (17.24 Q/ha) than RDF + Foliar application of ZnSO4 @ 2g/lit at 25 and 45 DAS (20.66 Q/ha). Application of micronutrient (ZnO) had helped in further increase in grain yields at both levels of ZnO (150% and 200% ZnO at 25 and 45 DAS). Among different treatments, significantly higher yield (24.36 Q/ha) was recorded with application of RDF + Foliar application of ZnO @ 200 ppm at 25 and 45 DAS than the only with RDF (17.4 Q/ha). With respect to method of application of ZnSO4 through soil and foliar application ZnSo4 @ 2g/lit at 25 and 45 DAS was found to be higher both levels of RDF (Pod yield of 14.6 Q/ha at RDF + Soil application of ZnSO4 @ 50 kg ha-1 and 17.24 Q/ha at RDF+ foliar application of ZnSO4@ 2g/lit at 25 and 45 DAS). With respect to other plant characteristics, comparatively more plant height (43.53 cm) at RDF + foliar application of ZnO @ 200 ppm at 25 and 45 DAS. Regarding yield attributes significantly higher test weight (30.9 g) were recorded at RDF + 200 ppm ZnO at 25 and 45 DAS. Post –harvest soil sample analysis showed highest availability of nutrients in respect of soil, the results revealed that there was no significance difference among the treatments regarding Avail. N, Available K and pH. The lowest Phosphorus (17.20 kg ha-1) was recorded with RDF+ Foliar application of nanoscale ZnO 200 ppm at 25 & 45 DAS and highest (24.46 kg ha-1) was recorded in T9 (RDF+ Foliar application of nanoscale ZnO 100 ppm at 25 & 45 DAS). 
 An investigation was initiated at Department of Soil science, Regional Agricultural Research Station, Chintapalle to examine the effects of nano zinc oxide on Groundnut (Arachis hypogea L.) growth, yield and Zn content in Leaves, stem and roots. A field experiment consisted of nine treatments comprised of T1: control, T2: RDF, T3: RDF+ Soil application ZnSO4@ 50 Kg/ha, T4: RDF+ Foliar application ZnSO4 2 g/L at 25 & 45DAS, T5: RDF+ Foliar application of nanoscale ZnO 150 ppm at 25 & 45 DAS, T6: RDF+ Foliar application of nanoscale ZnO 200 ppm at 25 & 45 DAS, T7: RDF+ Foliar application of nanoscale ZnO 400 ppm at 25 & 45 DAS, T8: RDF+ Foliar application of nanoscale ZnO 50 ppm at 25 & 45 DAS, T9: RDF+ Foliar application of nanoscale ZnO 100 ppm at 25 & 45 DAS.

The Solution Combustion Synthesis of ZnO Powder for the Photodegradation of Phenol

Nanoscale and submicron powder of zinc oxide (ZnO) is known as a highly efficient photocatalyst that is promising for solving the problem of wastewater treatment from toxic organic pollutants including phenol and its derivatives. The results of laboratory studies of ZnO preparation by a simple, energy-saving, and highly productive method of solution–combustion synthesis from a mixture of solutions of zinc nitrate and glycine, as well as the use of the ZnO powder synthesized by combustion for the photocatalytic decomposition of phenol, are presented. The modes and characteristics of combustion, phase composition, chemical composition, and structure of the combustion product at different ratios of glycine with zinc nitrate were determined. It is shown that calcination at 650 °C reduces the content of carbon impurity in the combustion product to ~1 wt.% and leads to obtaining ZnO powder in the form of porous agglomerates up to 100 μm in size sintered from crystalline nanoscale and submicron ZnO particles with an average crystallite size of 44 nm. The ZnO powder exhibits high photocatalytic activity, leading to the almost complete degradation of phenol in an aqueous solution under the action of ultraviolet irradiation in less than 4 h.

Effect of polar/non-polar facets on the transformation of nanoscale ZnO in simulated sweat and potential impacts on the antibacterial activity

The use of nanoscale zinc oxide (n-ZnO) in the personal care products would cause interactions between n-ZnO and human sweat. Facet engineering has been applied to n-ZnO to improve its activity. Nevertheless, it is not clear whether the exposed facet would affect transformation of n-ZnO in sweat. Herein, we prepared ZnO nanoneedles with the dominant (1010) non-polar facet (i.e., ZnO-1010) and ZnO nanoflakes with the dominant (0001) polar facet (i.e., ZnO-0001), respectively. We found that n-ZnO can undergo chemical transformation in the simulated sweat within 168 h or 24 h, transforming into amorphous materials and Zn3(PO4)20.4 H2O and/or Na(ZnPO4)·H2O. Given the rate constant (e.g., 0.093 h−1 for ZnO-0001 vs. 0.033 h−1 for ZnO-1010) of ZnO depletion and components of the precipitate from the simulated sweat, nevertheless, the transformation is highly dependent on the dominant exposed facet of n-ZnO. The ZnO-0001 relative to ZnO-1010 would likely undergo chemical transformation, demonstrating that the (0001) polar facet compared to (1010) non-polar facet had a superior activity to the dihydrogen phosphate anions in the simulated sweat, which is supported by density functional theory calculations. The chemical transformation can affect the antibacterial activity of n-ZnO to E. coli, moderating the toxicity due to a great decrease in the concentration of the dissolved zinc. In total, our findings provided insights into the facet-dependent transformation for n-ZnO in the simulated sweat, improving our understanding of potential risk of n-ZnO.

Investigation of mechanical properties and antibacterial behavior of WE43 magnesium-based nanocomposite

The aim of this study is to develop a biodegradable magnesium-based nanocomposite with enhanced mechanical and antibacterial properties. To achieve this goal, nano- and micro-scale zinc oxide (ZnO) and copper-zinc oxide (Cu/ZnO) reinforcements were incorporated into WE43 magnesium alloy, as the matrix of the nanocomposite. High purity ZnO and Cu/ZnO were synthesized by solution combustion with citric acid fuel using conventional and microwave heating, resulting in nanometer and micrometer particles, respectively. Friction stir processing (FSP) was employed to develope the magnesium-based composites. ZnO and Cu/ZnO powders were implemented into the WE43 base plate with either drilling holes or machining grooves. Hole-inserted additives resulted in more uniform particle distribution than groove-inserted ones. In addition, nanoscale ZnO and Cu/ZnO particles showed more uniform distribution compared to microscale ZnO. The addition of Cu/ZnO particles yielded the highest level of antibacterial activity, compressive strength and micro hardness of the composite. The antibacterial performance of the composite was in line with the fact that Cu/ZnO powder showed more pronounced antibacterial properties than ZnO powders. In addition, groove-inserted Cu/ZnO composite showed compressive strength of 527 MPa and hardness of 90.7 Hv, which were significantly higher than the values of 300 MPa and 78.7 Hv obtained for groove-inserted ZnO composites. It should be noted that the un-processed monolithic WE43 alloy had a compressive strength of 138 MPa and hardness of 66.8 Hv.

(Invited) Discovering Bottlenecks and Opportunities in Hybrid Solar Light Harvesting Systems By Ultrafast X-Ray Spectroscopy

A prerequisite for advancing hybrid solar light harvesting systems is a comprehensive understanding of photoinduced electronic dynamics across a wide range of spatial and temporal scales. Time-resolved spectroscopy techniques in the optical domain have proven instrumental in identifying critical timescales of fundamental processes, such as interfacial charge transfer, charge migration, and carrier lifetimes, which are intimately linked to a system's performance. New light source and instrument developments open opportunities to extend such studies into the X-ray regime. Due to their inherent elemental specificity and sensitivity to local electronic environments, time-domain X-ray spectroscopy techniques are uniquely suited to gain a microscopic picture of dynamics from well-defined reporter sites within often complex nanoscale light harvesting architectures. We will present new insights into fundamental photoinduced dynamics in several archetypical heterostructures based on femtosecond and picosecond time-resolved X-ray photoemission spectroscopy (TRXPS).The photoinduced transient charge redistribution in the model hybrid system of nanoporous zinc oxide (ZnO) sensitized by ruthenium bipyridyl chromophores is probed independently from the viewpoints of the molecular electron donor and the semiconductor acceptor.[1] Charge injection from the chromophore into the semiconductor is found to proceed via a transiently populated interfacial charge transfer (ICT) complex on an overall timescale of ~300 ps. Our results show that, even after release from the ICT states into the ZnO conduction band, the injected electrons remain localized within less than 6 nm from the interface, due to enhanced downward band-bending by the photo-injected charge carriers. This spatial confinement suggests that light-induced charge generation and transport in nanoscale ZnO photocatalytic devices proceeds predominantly within the defect-rich surface region, which may lead to enhanced surface recombination and explain their lower performance compared to titanium dioxide (TiO2)-based systems. The quantitative nature and surface sensitivity of TRXPS also provides direct access to the spatial separation of the holes remaining on the bipyridyl chromophores after charge injection from the semiconductor surface with sub-nm precision.Complementary femtosecond and picosecond TRXPS studies of photoinduced dynamics in copper-phthalocyanine(CuPc)-C60 heterojunctions provide a deeper understanding of both exciton migration pathways toward the interface as well as the absolute efficiency by which ICT states dissociate into separate charges.[2] The measurements reveal surprisingly efficient charge generation from triplet excitons and from the lowest lying ICT states, both of which were previously believed to be inactive during light-to-charge conversion.Photoinduced charge transfer dynamics between spherical gold nanoparticles (AuNPs) and a nanoporous film of TiO2 is monitored by picosecond TRXPS, providing direct access to the absolute photon-to-charge conversion efficiency and subsequent electron-hole recombination dynamics.[3] Preliminary results will be presented for the extension of the measurements into the ambient pressure regime, taking a first step toward the study of photoinduced interfacial chemistry by TRXPS in this model system for nanoplasmonic light harvesting applications.[1] S. Neppl et al., “Nanoscale Confinement of Photo-Injected Electrons at Hybrid Interfaces”, J. Phys. Chem. Lett. 12, 11951 (2021).[2] F. Roth et al., “Direct observation of charge separation in an organic light harvesting system by femtosecond time-resolved XPS”, Nat. Commun. 12, 1196 (2021).[3] M. Borgwardt et al., “Photoinduced Charge Carrier Dynamics and Electron Injection Efficiencies in Au Nanoparticle-Sensitized TiO2 Determined with Picosecond Time-Resolved X-ray Photoelectron Spectroscopy”, J. Phys. Chem. Lett. 11, 5476 (2020). Figure 1

Использование наноразмерного ZnO в составах для защитной обработки древесины

Wood natural structure can be considered as a suitable matrix for modifying with nanoparticles of various chemical nature. The research aims at obtaining a woodbased nanocomposite by modifying wood with compositions of waste vegetable oil and zinc oxide nanoparticles and studying the properties of this nanocomposite. Silver birch (Betula pendula) wood samples were chosen as study objects. Refined sunflower oil left after cooking was the oil base of the developed impregnating compositions; nanosized zinc oxide powder was the filler and modifier. The sol-gel method providing a narrow range of particle size distribution was used for synthesis of zinc oxide nanoparticles from Zn(NO3)2·6H2O as starting material. Aqueous ammonia solution was used as a precipitant. The synthesized zinc oxide nanoparticles contained no impurities, were mostly spherical and had the size less than 20 nm. The size of zinc oxide agglomerates was no more than 100 nm, allowing them to easily penetrate into the wood material cavities. A stable suspension of synthesized zinc oxide nanopowder in used sunflower oil was prepared and applied for wood modification by hot-and-cold bath treatment. It was found that the use of nanoscale zinc oxide accelerates the drying process of vegetable oil coating, increases the strength of such a coating and its resistance to external influences. The use of developed compositions improves the hydrophobic properties of wood, its moisture and water resistance, as well as reduces swelling in the tangential and radial directions. We have chosen the optimal dosage of nanosized zinc oxide (0.1 %) in compositions based on waste vegetable oil for protective treatment of birch wood. Impregnating compositions on the base of waste vegetable oil are environmentally safe and their use allows recycling food industry wastes.

Synthesis, Characterization, and Modeling of Aligned ZnO Nanowire-Enhanced Carbon-Fiber-Reinforced Composites.

This paper presents the synthesis, characterization, and multiscale modeling of hybrid composites with enhanced interfacial properties consisting of aligned zinc oxide (ZnO) nanowires and continuous carbon fibers. The atomic layer deposition method was employed to uniformly synthesize nanoscale ZnO seeds on carbon fibers. Vertically aligned ZnO nanowires were grown from the deposited nanoscale seeds using the low-temperature hydrothermal method. Morphology and chemical compositions of ZnO nanowires were characterized to evaluate the quality of synthesized ZnO nanowires in hybrid fiber-reinforced composites. Single fiber fragmentation tests reveal that the interfacial shear strength (IFSS) in epoxy composites improved by 286%. Additionally, a multiscale modeling framework was developed to investigate the IFSS of hybrid composites with radially aligned ZnO nanowires. The cohesive zone model (CZM) was implemented to model the interface between fiber and matrix. The damage behavior of fiber was simulated using the ABAQUS user subroutine to define a material’s mechanical behavior (UMAT). Both experimental and analytical results indicate that the hierarchical carbon fibers enhanced by aligned ZnO nanowires are effective in improving the key mechanical properties of hybrid fiber-reinforced composites.