Nanoscale Oxide Research Articles

Cold Spray Coatings of Complex Concentrated Alloys: Critical Assessment of Milestones, Challenges, and Opportunities

Complex concentrated alloys (CCAs) are structural and functional materials of the future with excellent mechanical, physical, and chemical properties. Due to the equiatomic compositions of these alloys, cost can hinder scalability. Thus, the development of CCA-based coatings is critical for low-cost applications. The application of cold spray technology to CCAs is in its infancy with emphasis on transition elements of the periodic table. Current CCA-based cold spray coating systems showed better adhesion, cohesion, and mechanical properties than conventional one-principal element-based alloys. Comprehensive mechanical behavior, microstructural evolution, deformation, and cracking of cold spray CC-based coatings on the same and different substrates are reviewed. Techniques such as analytical models, finite element analysis, and molecular dynamic simulations are reviewed. The implications of the core effects (high configurational entropy and enthalpy of mixing, sluggish diffusion, severe lattice distortion, and cocktail behavior) and interfacial nanoscale oxides on the structural integrity of cold spray CCA-based coatings are discussed. The mechanisms of adiabatic heating, jetting, and mechanical interlocking, characteristics of cold spray, and areas for future research are highlighted.

Graphene Oxide-Based Memristive Logic-in-Memory Circuit Enabling Normally-Off Computing.

Memristive logic-in-memory circuits can provide energy- and cost-efficient computing, which is essential for artificial intelligence-based applications in the coming Internet-of-things era. Although memristive logic-in-memory circuits have been previously reported, the logic architecture requiring additional components and the non-uniform switching of memristor have restricted demonstrations to simple gates. Using a nanoscale graphene oxide (GO) nanosheets-based memristor, we demonstrate the feasibility of a non-volatile logic-in-memory circuit that enables normally-off in-memory computing. The memristor based on GO film with an abundance of unusual functional groups exhibited unipolar resistive switching behavior with reliable endurance and retention characteristics, making it suitable for logic-in-memory circuit application. In a state of low resistance, temperature-dependent resistance and I-V characteristics indicated the presence of a metallic Ni filament. Using memristor-aided logic (MAGIC) architecture, we performed NOT and NOR gates experimentally. Additionally, other logic gates such as AND, NAND, and OR were successfully implemented by combining NOT and NOR universal logic gates in a crossbar array. These findings will pave the way for the development of next-generation computer systems beyond the von Neumann architecture, as well as carbon-based nanoelectronics in the future.

Supernano Crystals Boost the Initial Coulombic Efficiency and Capacity of Copper Benzene-1,3,5-Tricarboxylate for Li-Ion Batteries

Despite the high capacity of metal–organic framework (MOF) electrodes for Li-ion batteries (LIBs), the low initial Coulombic efficiency (ICE) due to irreversible and massive consumption of lithium ions in the initial cycle hinders their practical application. Nanoscale transition metal oxides (TMOs) can activate the electrochemically stable Li–O bonds and therefore improve the ICE. Hence, copper benzene-1,3,5-tricarboxylate (Cu-BTC) rods with encapsulated supernano CuO were synthesized in a straightforward way using CuO and H3BTC as the metal source and organic ligand, respectively. By altering the reaction temperature, the size of CuO crystals can be adjusted from 6.98 to 2.72 nm. The CuO-doped Cu-BTC (40 °C) anode delivers an optimal capacity of 990.7 mA h g–1 (under 0.2 A g–1) after 100 cycles and the highest ICE of 61.84%, which exceeds the other counterparts. Such superior electrochemical properties are closely related to the size and content of CuO. This strategy introduces supernano CuO into Cu-BTC, which can be generalized to construct other in situ-formed TMO-doped MOF compounds as efficient lithium storage materials.

Effects of Fe self-ion irradiation on a low carbon MX-ODS steel at 550°C

Oxide Dispersion Strengthened (ODS) steels with nano-scale oxides have become one of the candidate materials used in advanced nuclear reactor systems. A novel MX-ODS steel with extremely low carbon content was irradiated with 3 MeV Fe ions at 550°C up to peak damage of 70 dpa. The steel contains uniformly distributed Y2O3 nano-precipitates with an average size of 3.5 nm and a number density of 5 × 1022/m3. A V-rich shell was found surrounding the core of Y, O, and Si at some particles. Two types of large precipitates, Y-Ta-Si oxides, and VN, were observed in the steel instead of carbides. Voids of very small size are present due to irradiation and the calculated void swelling was only 0.004%, suggesting good irradiation tolerance of the MX-ODS steel in this study. Fine and dense oxide nano-precipitates and their shell-core structure remained stable while the shape of large precipitates changed after irradiation.

Effects of Al content on microstructure and tensile properties of Ni-based ODS superalloys

Two kinds of Ni-based oxide dispersion strengthening (ODS) superalloys with high/low Al contents, ODS-HA (Ni-20Cr-4.5Al-0.5Ti-0.6Y2O3-0.6Zr, wt%) and ODS-LA (Ni-20Cr-0.3Al-0.5Ti-0.6Y2O3-0.6Zr), were manufactured by mechanical alloying and hot isostatic pressing to investigate the effects of Al content on microstructure and tensile property. The results showed that ODS-HA is strengthened by both Ni3Al precipitates and nanoscale oxides together with refined grain size, and ODS-LA is strengthened mainly by nanoscale oxides. Type and size of nanoscale oxides depend on Al content. Y4Zr3O12, Y2TiO5, monoclinic Y4Al2O9 (YAM), hexagonal YAlO3 (YAH) and YAlO3 perovskite (YAP) are observed in ODS-LA while only Y4Zr3O12 and YAP are found in ODS-HA. This causes the change of size and number density of oxides in two kinds of ODS alloys. High Al content results in increased tensile strength and decreased ductility.

Grain Boundary-Rich Copper Nanocatalysts Generated from Metal-Organic Framework Nanoparticles for CO2 -to-C2+ Electroconversion.

Due to severe contemporary energy issues, generating C2+ products from electrochemical carbon dioxide reduction reactions (eCO2 RRs) gains much interest. It is known that the catalyst morphology and active surface structures are critical for product distributions and current densities. Herein, a synthetic protocol of nanoparticle morphology on copper metal-organic frameworks (n-Cu MOFs) is developed by adjusting growth kinetics with termination ligands. Nanoscale copper oxide aggregates composed of small particulates are yielded via calcining the Cu-MOF nanoparticles at a specific temperature. The resulting nanosized MOF-derived catalyst (n-MDC) exhibits Faradaic efficiencies toward ethylene and C2+ products of 63% and 81% at -1.01V versus reversible hydrogen electrode (RHE) in neutral electrolytes. The catalyst also shows prolonged stability for up to 10h. A partial current density toward C2+ products is significantly boosted to -255mA cm-2 in an alkaline flow cell system. Comprehensive analyses reveal that the nanoparticle morphology of pristine Cu MOFs induces homogeneous decomposition of organic frameworks at a lower calcination temperature. It leads to evolving grain boundaries in a high density and preventing severe agglomeration of copper domains, the primary factors for improving eCO2 RR activity toward C2+ production.

Chronic exposure to complex metal oxide nanomaterials induces production of reactive oxygen species in bacteria

Chronic exposure of Shewanella oneidensis to nanoscale lithiated nickel manganese cobalt oxide induces ROS production in the bacteria, filamentation, vesicle formation, DNA damage, and evolution of resistance to other stressors such as antibiotics.

Experimental observation of the role of countercations in modulating the electrical conductance of Preyssler-type polyoxometalate nanodevices.

Polyoxometalates are nanoscale molecular oxides with promising properties that are currently explored for molecule-based memory devices. In this work, we synthesize a series of Preyssler polyoxometalates (POMs), [Na⊂P5W30O110]14-, stabilized with four different counterions, H+, K+, NH4+, and tetrabutylammonium (TBA+). We study the electron transport properties at the nanoscale (conductive atomic force microscopy, C-AFM) of molecular junctions formed by self-assembled monolayers (SAMs) of POMs electrostatically deposited on the ultraflat gold surface prefunctionalized with a positively charged SAM of amine-terminated alkylthiol chains. We report that the electron transport properties of P5W30-based molecular junctions depend on the nature of the counterions; the low-bias current (in the voltage range [-0.6 V; 0.6 V]) gradually increases by a factor of ∼100 by changing the counterion in the order: K+, NH4+, H+ and TBA+. From a statistical study (hundreds of current-voltage traces) using a simple analytical model for charge transport in nanoscale devices, we show that the energy position of the lowest unoccupied molecular orbital (LUMO) of P5W30 with respect to the Fermi energy of the electrodes increases from ∼0.4 eV to ∼0.7 eV and that the electrode coupling energy also increases from ∼0.05 to 1 meV in the same order from K+, NH4+, H+ to TBA+. We discuss several hypotheses on the possible origin of these features, such as a counterion-dependent dipole at the POM/electrode interface and counterion-modulated molecule/electrode hybridization, with, in both cases, the largest effect in the case of TBA+ counterions.

Pilot-Scale Field Demonstration of Environmental Nanotechnology for Groundwater Defluoridation

Fluoride contamination in groundwater is a global issue. Nanoscale oxides of Zr(IV), Al(III), and Ti(IV) can form the inner-sphere complex with fluoride through ligand exchange, offering a new chance for efficient groundwater purification. However, pilot-scale field demonstration of nanotechnology in groundwater defluoridation is very rare. Herein, we conducted a 150-day field defluoridation study using the nanocomposite HZO@D201, which was prepared by encapsulating nano-hydrated zirconium oxide (HZO) inside the strongly basic anion exchanger D201. The HZO@D201 beads were packed in five-stage series columns (40 L for each column), and the groundwater was pumped through the columns sequentially. The effective treatment amount for the single column ([F–] < 1.0 mg/L) exceeded ∼3000 bed volume (BV). The exhausted HZO@D201 was fully refreshed through ex situ treatment with NaOH–NaCl solution for repeated use without significant loss in defluoridation reactivity. Owing to the specific interaction with HZO, the fluoride concentration could be steadily reduced below 1.0 mg/L throughout the 150-day field demonstration, while the common anions coexisting in groundwater (K+, Na+, Ca2+, Mg2+, SO42–, Cl–, etc.) remained almost unchanged. The operational cost for deep defluoridation was estimated as 0.574 RMB per ton of groundwater, much less than that of the widely studied reverse osmosis. TEM, XPS, and Fourier transform infrared (FTIR) analysis indicated that negligible change occurred in the structure and chemical composition of HZO@D201 after the long-term field assay. This study may inspire more attempts at the pilot scale and engineering demonstration of nano-enabled water treatment techniques.

Enhanced high-rate cycling performance of LiMn2O4 cathode materials by coating nano-TiO2

Abstract LiMn2O4 has the advantages of low cost and no pollution, and is widely regarded as a large-scale lithium battery cathode material. However, the capacity decays rapidly, which seriously affects the application of LiMn2O4 cathode materials. Therefore, improving the cycling performance of LiMn2O4 is the focus of current research. LiMn2O4 precursors were prepared by chemical precipitation and the precursors were coated to prepare LiMn2O4/TiO2 composites. X-ray diffraction and scanning electron microscopy showed that LiMn2O4 had been successfully combined with TiO2. Electrode charge–discharge and electrochemical impedance tests showed that LiMn2O4/TiO2 had the best cycle performance at high rates. The initial discharge capacities of LiMn2O4/TiO2 reached 106.4 mAh·g−1 at 0.2 C. After 100 cycles, the 2 C capacity retention rates was 76.3 %, compared to only 66.5 % for pristine LiMn2O4. The improved electrochemical performance was attributed to the nanoscale oxides hindering the reaction between the electrolyte and the electrode, which effectively improved the stability of the material during high current charge and discharge.

Influence of high-temperature oxidation of SiC powders on curing properties of SiC slurry for digital light processing

Fabrication of silicon carbide (SiC) ceramics by digital light processing (DLP) technology is difficult owing to high refractive index and high ultraviolet (UV) absorptivity of SiC powders. The surface of the SiC powders can be coated with silicon oxide (SiO₂) with low refractive index and low UV absorptivity via high-temperature oxidation, reducing the loss of UV energy in the DLP process and realizing the DLP preparation of the SiC ceramics. However, it is necessary to explore a high-temperature modification process to obtain a better modification effect of the SiC powders. Therefore, the high-temperature modification behavior of the SiC powders is thoroughly investigated in this paper. The results show that nano-scale oxide film is formed on the surface of the SiC powders by short-time high-temperature oxidation, effectively reducing the UV absorptivity and the surface refractive index (<i>n</i>ʹ) of the SiC powders. When the oxidation temperature is 1300 ℃, compared with that of unoxidized SiC powders, the UV absorptivity of oxidized SiC powders decreases from 0.5065 to 0.4654, and a curing depth of SiC slurry increases from 22±4 to 59±4 μm. Finally, SiC green bodies are successfully prepared by the DLP with the the oxidized powders, and flexural strength of SiC sintered parts reaches 47.9±2.3 MPa after 3 h of atmospheric sintering at 2000 ℃ without any sintering aid.

Cold spray manufacturing of oxide-dispersion strengthened (ODS) steels using gas-atomized and ball-milled 14YWT powders

The cold spray deposition process has been investigated for the manufacture of 14YWT oxide-dispersion strengthened (ODS) steel, a nanostructured ferritic alloy (NFA), using gas-atomized and ball-milled feedstock powders. Cold spraying of the gas-atomized powder resulted in a thick dense deposit, but annealing them above 900 °C induced grain growth and heterogeneous precipitation of nanoparticles, thus resulting in lower hardness (∼ 170 HV) compared to 14YWT ODS steel manufactured by the conventional method. The ball-milled powder (Fe-14Cr-3W-0.4Ti-0.2Y-0.125O) was cryomilled in liquid N2 to achieve small particle sizes followed by annealing in a H2/Ar environment at 1000 °C and 1100 °C to reduce the hardness from ∼ 8 GPa to ∼ 5 GPa. Both smaller particle sizes and lower hardness of annealed powders made them amenable to the cold spray deposition process, resulting in thick and dense deposits, while retaining the favorable fully solutionized microstructure of the ball-milled powders. The microstructure of the as-deposited ODS exhibited very fine grain sizes (50–250 nm) with a uniform dispersion of Y-Ti-O nanoprecipitates in the ferritic steel matrix. The hardness values of the cold spray deposits using the powders annealed at 1000 °C and 1100 °C was 770 HV and 496 HV, respectively. Post-heat treatment of the as-deposited material up to 1100 °C showed a high-density microstructure with uniformly dispersed nanoscale oxide particles. The hardness of the annealed deposits up to 1000 °C had a notably higher hardness than bulk 14YWT ODS steel manufactured by conventional methods. The study demonstrates that cold spray deposition of the microstructurally-tailored feedstock powders can be used to successfully manufacture ODS steel with microstructure and properties comparable to those produced by the conventional methods, while providing for an attractive option for the more rapid and cost-effective manufacturing of ODS steel cladding tubes.

Improved microstructure and mechanical properties of ODS-CoCrFeNiMn high entropy alloys by different Ti, Zr and Y2O3 addition

Four ODS-CoCrFeNiMn high entropy alloys (HEAs) with different Ti/Zr/Y2O3 addition were produced by powder metallurgy. The role of Ti, Zr, Y2O3 on improving microstructure and mechanical properties of ODS-CoCrFeNiMn HEAs was studied. The type of nanoscale oxides is effectively changed from Y2O3 (1Y alloy), Y2TiO5, YTiO3 and Y2Ti2O7 (1YT), Y4Zr3O12 and Y2Zr2O7 (1YZ) to YTiO3, Y2TiO5, Y2Ti2O7, Ti2O3 (1YTZ) by introducing different addition. The joint addition of Ti, Zr and Y2O3 in 1YTZ has the most significant refinement on grain size and increases number density of nanoscale oxides, which reach 130 nm and 2.01 × 1021/m3, respectively. The well refined grains and high density of nanoscale oxides in 1YTZ alloy lead to the highest hardness and compressive yield strength, which are 449 HV and 1309 MPa, respectively. The different formation mechanisms of nanoscale oxides due to different addition and its influence on mechanical properties in ODS-CoCrFeNiMn HEAs are disclosed. Data availability statementAll data included in this study are available upon request by contact with the corresponding author.

Silicon nitride ceramics with sintering oxide additives obtained from organoyttriumoxanealumoxane

Sintered blanks for spherical bodies of rolling from silicon nitride ceramics were obtained using the addition of an yttrium-containing organoalumoxane ― element organic oligomer, soluble in traditional organic solvents and rolling in pyrolysis into an oxide aluminum-sintering additive in a given mass ratio Al2O3/Y2O3 = 3/1. Studies conducted using thermogravimetry, X-ray phase analysis, optical and electron scanning microscopy showed that the feature of the use of elementoxane instead of the sintering additives of aluminum and yttrium oxides powder is a uniform distribution of aluminum and yttrium oxides in Si3N4- ceramics and the chemical activity of pyrolysis products of organoyttriumoxanealumoxane (OYA), Including amorphous nanoscale oxides on the surface of the Si3N4 powder. Density, porosity, microstructure and the degree of purity of the polished surface of the obtained ceramics indicate its prospects for use as a blank of high-quality rolling bodies. Ill. 6. Ref. 16. Tab. 1.

Graphene Oxide Nanoscale Platform Enhances the Anti-Cancer Properties of Bortezomib in Glioblastoma Models.

Graphene-based 2D nanomaterials possess unique physicochemical characteristics which can be utilized in various biomedical applications, including the transport and presentation of chemotherapeutic agents. In glioblastoma multiforme (GBM), intratumorally administered thin graphene oxide (GO) nanosheets demonstrate a widespread distribution throughout the tumor volume without impact on tumor growth, nor spread into normal brain tissue. Such intratumoral localization and distribution can offer multiple opportunities for treatment and modulation of the GBM microenvironment. Here, the kinetics of GO nanosheet distribution in orthotopic GBM mouse models is described and a novel nano-chemotherapeutic approach utilizing thin GO sheets as platforms to non-covalently complex a proteasome inhibitor, bortezomib (BTZ), is rationally designed. Through the characterization of the GO:BTZ complexes, a high loading capacity of the small molecule on the GO surface with sustained BTZ biological activity in vitro is demonstrated. In vivo, a single low-volume intratumoral administration of GO:BTZ complex shows an enhanced cytotoxic effect compared to free drug in two orthotopic GBM mouse models. This study provides evidence of the potential that thin and small GO sheets hold as flat nanoscale platforms for GBM treatment by increasing the bioavailable drug concentration locally, leading to an enhanced therapeutic effect.

A review on adsorption efficiency of widely adopted adsorbents used in Defluoridation of aqueous media

The review article provides an insight on various adsorbents and their efficiency in fluorideremoval fromdrinking and waste water. The capacity of fluoride removal of adsorbent is dependent on pH, contact time,temperature, surface area of adsorbent and initial concentration of fluoride solution etc. In comparison tothe traditional natural methods, the synthetic and nanostructure-based adsorbents, exhibited higherperformance and efficiency of defluorination which provides a sustainable approach to safe drinking waterquality. The present paper deals with some widely adopted natural adsorbent, synthetic and nanostructurebasedadsorbents. The natural adsorbent includes, thermally treated lateritic soil, modified natural magnetiteore (Fe3O4) with aluminum and lanthanum ions, lateritic soils, Titanium hydroxide, limestone (LS) andaluminium hydroxide, sedimentation with calcium and aluminium. The Synthetic adsorbent includes,Surface-functionalized polyurethane foam (SPUF); Schwertmannite; Carbonaceous material from pyrolysisof sewage sludge; Chitosan. And the effective adsorbent nano scale structure includes, nanoscale aluminiumoxide hydroxide (AlOOH), Magnetic iron oxide/aluminium hydroxide composite, sulfatedoped Fe3O4/Al2O3 nanoparticles, nano-scale aluminum oxide hydroxide (nano-AlOOH), Graphene Nanoparticlesadsorbent, Al2O3/Bio-TiO2 nano composite (ABN), Green synthesized Fe3O4/Al2O3nanoparticles with coatedpolyurethane foams etc. The activated alumina is most conventional fluoride adsorbing material. However,activated alumina performs well in acidic environment with complex regeneration issue. Although othertraditional adsorbents remove fluoride from water but they have lower efficiency, which restrict theirapplication. In case of synthetic and nano structured based adsorbents, due to increased surface area, nontoxicnature, limited solubility in water and high adsorption efficiency, these methods are widely accepted andproven environmentally suitable.

Early-stage evolution of nanoscale oxides on Ni(111) and Ni-Cr(111) surfaces

The early stages of oxidation on Ni(111) and Ni-18 wt%Cr(111) surfaces were studied with scanning tunneling microscopy/spectroscopy. After exposure to oxygen at 500 °C, chemisorbed p(2 ×2)O adlayers appear on Ni(111) without oxide formation. On the Ni-Cr(111) surface 2D NiO(100) layers rapidly accumulate on the terraces. These coexist with Cr-rich clusters, which coalesce as oxidation progresses. Larger oxide nodules with 3D-island morphology are identified as chromia and are found embedded in the NiO(100). Spectroscopy reveals electronic heterogeneity, highlighting the chemical variation between each oxide species. A schematic is constructed that highlights the associated Ni- and Cr- reaction pathways on Ni-Cr(111) alloy surfaces.

Effects of hot rolling and annealing temperature on microstructure and tensile properties of a Zr-containing Ni-based ODS superalloy

A Ni-based ODS superalloy with composition of Ni-20Cr-0.5Ti-0.3Al-0.6Y2O3-0.6Zr (in mass%) was prepared by mechanical alloying and hot isostatic pressing. Hot rolling was carried out at 1100 °C with different reduction ratio (40 %, 50 % and 60 %) and different annealing temperature (1200 °C, 1250 °C and 1300 °C) to investigate their influence on nanoscale oxides, grain and high temperature tensile properties. The results showed that high-density nanoscale oxides Y4Zr3O12 are formed in the Zr-containing Ni-based ODS alloy. Hot rolling and annealing result in the slight increase of oxide size and decrease of oxide density. The growth rate of oxides obeys fifth-law, which is called pipe diffusion along dislocation. The diffusion activity energy is derived as 827 kJ/mol. Average oxide size decreases and number density increases by decreasing rolling reduction ratio or annealing temperature. The size of columnar grain and grain aspect ratio increase with increase of annealing temperature which results into enhanced ultimate tensile strength and improved ductility at 800 °C. In addition, increasing rolling reduction ratio refines grain size and reduces grain aspect ratio in the alloy. The strength of the alloy annealed at 1300 °C with a reduction ratio of 50 % is the highest which is approximately 300 MPa at 800 °C.

Effect of Zr content on microstructure and hardness of ODS-FeCrAl alloys

Oxide dispersion strengthened (ODS) Fe-12Cr-5Al-2 W-xZr (x = 0, 0.3, 0.6, 1.0 wt%) alloys were produced by mechanically alloying and spark plasma sintering. The size and distribution of grain, number density, size distribution and types of nanoscale oxides as well as hardness of the ODS alloys were analyzed by EBSD, TEM, HRTEM and an indentation experiment, respectively. The results showed that the grain size is not sensitive to Zr content, but the increase of Zr content is helpful for the homogenization of grain size. With the increase of Zr content from 0 to 0.6 wt%, the number density of oxides is increased from 1.66 × 1021 m−3 to 9.94 × 1022 m−3, while the mean size of oxides is decreased from 21.2 nm to 11.1 nm. The coarsening of oxides occurs when Zr is up to 1 wt%. In Zr-free alloy, nano-oxides are YAlO3 with perovskite structure (YAP) and α-Al2O3. In Zr-containing ODS alloys, the trigonal δ-phase Y4Zr3O12, YAP and α-Al2O3 are observed. An appendage oxide, Y4Zr3O12/YAP/α-Al2O3, is found in the alloy with 1.0 wt% Zr and the possible formation mechanism is briefly analyzed. The hardness of 6.03 GPa is achieved in the 0.6 wt% Zr alloy.

Foliar-applied nanoscale zero-valent iron (nZVI) and iron oxide (Fe3O4) induce differential responses in growth, physiology, antioxidative defense and biochemical indices in Leonurus cardiaca L

The impacts of nZVI and iron oxides on growth, physiology and elicitation of bioactive antioxidant metabolites in medicinal aromatic plants must be critically assessed to ensure their safe utilization within the food chain and achieve nutritional gains. The present study investigated and compared the morpho-physiological and biochemical changes of Leonurus cardiaca L. plants as affected by various concentrations (0, 250, 500 and 1000 mg L−1) of nZVI and Fe3O4. The foliar uptake of nZVI was verified through Scanning Electron Microscopy (SEM) images and Energy Dispersive X-ray (EDX) analytical spectra. Plants exposed to nZVI at low concentration showed comparatively monotonic deposition of NPs on the surface of leaves, however, the agglomerate size of nZVI was raised as their doses increased, leading to remarkable changes in anatomical and biochemical traits. 250 mg L−1 nZVI and 500 mg L−1 Fe3O4 significantly (P < 0.05) increased plant dry matter accumulation by 37.8 and 27% over the control, respectively. The treatments of nZVI and Fe3O4 at 250 mg L−1 significantly (P < 0.01) improved chlorophyll a content by 22.4% and 15.3% as compared to the control, and then a rapid decrease (by 14.8% and 4.1%) followed at 1000 mg L−1, respectively. Both nZVI and Fe3O4 at 250 mg L−1 had no significant impact on malondialdehyde (MDA) formation, however, at an exposure of 500–1000 mg L−1, the MDA levels and cellular electrolyte leakage were increased. Although nZVI particles could be utilized by plants and enhanced the synthesis of chlorophylls and secondary metabolites, they appeared to be more toxic than Fe3O4 at 1000 mg L−1. Exposure to nZVI levels showed positive, negative and or neutral impacts on leaf water content compared to control, while no significant difference was observed with Fe3O4 treatments. Soluble sugar, total phenolics and hyperoside content were significantly increased upon optimum concentrations of employed treatments-with 250 mg L−1 nZVI being most superior. Among the extracts, those obtained from plants treated with 250–500 mg L−1 nZVI revealed the strong antioxidant activity in terms of scavenging free radical (DPPH) and chelating ferrous ions. These results suggest that nZVI (at lower concentration) has alternative and additional benefits both as nano-fertilizer and nano-elicitor for biosynthesis of antioxidant metabolites in plants, but at high concentrations is more toxic than Fe3O4.