MgO Nanostructures Research Articles

Low-Temperature Activation and Coupling of Methane on MgO Nanostructures Embedded in Cu2O/Cu(111).

The efficient conversion of methane into valuable hydrocarbons, such as ethane and ethylene, at relatively low temperatures without deactivation issues is crucial for advancing sustainable energy solutions. Herein, AP-XPS and STM studies show that MgO nanostructures (0.2-0.5 nm wide, 0.4-0.6 Å high) embedded in a Cu2O/Cu(111) substrate activate methane at room temperature, mainly dissociating it into CHx (x = 2 or 3) and H adatoms, with minimal conversion to C adatoms. These MgO nanostructures in contact with Cu2O/Cu(111) enable C-C coupling into ethane and ethylene at 500 K, a significantly lower temperature than that required for bulk MgO catalysts (>700 K), with negligible carbon deposition and no deactivation. DFT calculations corroborate these experimental findings. The CH4,gas → *CH3 + *H reaction is a downhill process on MgO/Cu2O/Cu(111) surfaces. The activation of methane is facilitated by electron transfer from copper to MgO and the existence of Mg and O atoms with a low coordination number in the oxide nanostructures. The formation of O-CH3 and O-H bonds overcomes the energy necessary for the cleavage of a C-H bond in methane. DFT studies reveal that smaller Mg2O2 model clusters provide stronger binding and lower activation barriers for C-H dissociation in CH4, while larger Mg3O3 clusters promote C-C coupling due to weaker *CH3 binding. All of these results emphasize the importance of size when optimizing the catalytic performance of MgO nanostructures in the selective conversion of methane.

Fabrication of nanostructured MgO:Fe as NO2 gas sensor prepared by spray pyrolysis technique

Nanostructured MgO:Fe was fabricated by spray Pyrolysis technique (SPT). XRD verifies MgO's cubic structure. The MgO thin film's crystallite size increased to 10.7–15.41 nm due to doping. SEM pictures display The surface becomes rougher and the grain size increases with concentration. The ideal MgO's average transmission value in the visible spectrum was 70%. The Tauc relation was used to calculate Eg, which decreased for MgO:Fe doping at 4%wt concentration from 362.1 to 3.52 eV. Resistance change as a measure of film sensitivity to gas indicates that MgO is a p-type semiconductor, with the maximum resistance being shown by MgO:Fe at 4%wt. The sensitivity of MgO films to NO2 diminishes as Fe content increases.

Tribological Properties of h-BN, Ag and MgO Nanostructures as Lubricant Additives in Vegetable Oils

There exists an ever-growing need for sustainable engineering solutions to improve emission control and the energy efficiency of tribosystems. This study examines the tribological properties of two environmentally friendly vegetable fluids, soybean and sunflower oil, with the addition of three non-toxic nanostructures (h-BN, silver and MgO) at different concentrations. It was found that nanostructures added to vegetable oils at specific concentrations can exhibit good friction reduction and wear preventive properties. The addition of h-BN nanosheets in sunflower oil decreased the coefficient of friction and the wear damage, as measured by the wear scar diameter. Silver and magnesium oxide nanoparticles further reduced the friction and wear, respectively. In addition to the tribological testing of the samples, investigations were performed using an optical microscope, SEM and EDX to elucidate the mechanisms that may have led to the observed friction reduction and wear-preventive properties of different nanostructure additives. The thermophysical properties of the samples were also measured. It was found that the thermal conductivity of both base oils could be enhanced by 24% when using h-BN at 0.25 wt% concentration.

Enhancing catalytic and antibacterial activity with size-controlled yttrium and graphene quantum dots doped MgO nanostructures: A molecular docking analysis

Designing efficient catalysts that possess large number of active sites, high catalytic activity and selectivity while also exhibiting strong antimicrobial activity is a challenging task because of poor control over material fabrication. Therefore, developing new and innovative approaches for the synthesis of catalytic materials is crucial for addressing these challenges. Here, we report the controlled fabrication of GQDs/Y-doped MgO nanoparticles achieved by co doping of yttrium (Y) and graphene quantum dots (GQDs) in magnesium oxide (MgO) based nanostructures (NSs) using the co-precipitation method. The co-doping of GQDs and Y was controlled by manipulating the ratio of precursors where introduction of GQD resulted in higher surface area and enhanced conductivity while the doping of Y enhanced the number of active sites in the final product. The GQDs/Y-doped MgO exhibited an average particle size of ∼50 nm and a bandgap of 3.6 eV. Owing to these excellent characteristics, the GQDs/Y-doped MgO was utilized as a catalyst for treatment of the organic pollutants from water as well as antibacterial activity. The modified GQDs/Y-doped MgO nanostructure exhibited excellent activity of over 99.9 % for dye removal and versatility in a broad range of pH which clearly indicated the application in a range of different environments. Furthermore, the GQDs/Y-doped MgO exhibited excellent antibacterial activity against Escherichia Coli (E. Coli) bacteria. To gain further insights into the origins of this excellent activity response, the molecular docking simulations (MDS) is utilized against DNA gyrase and FabI (two enzymes critical to nucleic acid and fatty acid biosynthesis, respectively), to uncover the mechanism behind the observed antibacterial effects. In summary, the modified catalyst provides a pathway to design highly efficient catalysts for all pH range water treatment as well as good activity against microbes.

Structural control of nanoporous frameworks consisting of minimally stacked graphene walls

This mini-review provides an in-depth analysis of the formation and post-processing of nanoporous graphene materials via methane chemical vapor deposition (CH4-CVD) using nanostructured metal oxide templates, including Al2O3, MgO, and SiO2. Initially, the formation of graphene sheets is discussed in terms of the role of CH4-CVD, the influence of templates, and the underlying mechanism for tailoring the structures of the graphene-based materials. Following this, the discussion extends to the post-graphene formation process. We focus on key steps, including template removal and graphene repair via zipping reactions at high temperatures. Additionally, we evaluate the conditions to prevent undesired structural transformations. The correlation between the structural features and transformations occurring during post-processing is also examined. The materials fabricated through these methods exhibit impressive properties of high porosity, minimal edge sites, superior oxidation resistance, and elasticity, positioning them as promising materials in various applications.

Dielectric performance of nanostructured magnesium oxide and effect of cobalt substitution

Here, we examined effect of Co substitution on dielectric characteristics of MgO nanostructures at various doping concentrations with the view to finding its use as a capacitor. The grain and grain boundary have significant impact on the dielectric characteristics' temperature and frequency dependency. Pure and Co doped MgO nanostructures showed dramatic drop in their dielectric constant and dielectric loss with increasing frequency. Reverse micelle micro emulsions of water-cyclohexane-CTAB ternary oil-surfactant-water systems were used to synthesize both pure and Co doped MgO nanostructures. Energy-dispersive X-ray spectroscopy (EDX), powder X-ray diffraction (PXRD), dynamic light scattering based particle size analysis (DLS-PSA), photoluminescence (PL), and Raman spectroscopy were used to analyze the synthesized materials. Different frequency and temperature range were studied for the complex permittivity of dielectric characteristics (ε * = ε'-jε") and the loss tangent (tanδ) and based on the experimental data, ε', ε", tanδ decreases as frequency and temperature increase.

Synthesis and dielectric studies of Ni doped MgO nanostructure

Pure and Ni-doped MgO nanostructures were synthesized using reverse micelle approach, which produced a size distribution with narrow range effectively. By using X-ray diffraction, the face cantered cubic structure of each sample was confirmed. Energy dispersive analysis of X-ray confirms composition of all the samples. By using the high-resolution transmission mode of electron microscopy, the morphology and size of the nanostructure were validated. Utilizing reflectance spectra, the Kubelka–Munk equation has been used to calculate the optical bandgap which is ref shifted with doping. Vibrational mode analysis was done using Raman spectroscopy. Broadband dielectric spectroscopy was used to measure the dielectric parameters revealing improved dielectric performance for Ni doped MgO nanostructure. Because of the generation of oxygen vacancies by dopant addition, lower frequency dielectric loss and a higher dielectric constant were achieved. The impedance behavior in various frequency regimes demonstrated how effectively conductive grains and insulating grain borders contributed. Looking at the literature survey, this is very first attempt to study the temperature and frequency dependent dielectric study for Ni doped MgO nanostructure.

A Variant Gel-Combustion Approach to Impregnate Nanostructured MgO Coating on Cotton Fibers for Antibacterial Textile Applications

A Variant Gel-Combustion Approach to Impregnate Nanostructured MgO Coating on Cotton Fibers for Antibacterial Textile Applications

Investigation of size and morphology effects of MgO nanostructures on the properties of MgO/transformer oil-based nanofluids

Investigation of size and morphology effects of MgO nanostructures on the properties of MgO/transformer oil-based nanofluids

Kolanut-mediated magnesium oxide nanostructures for biomedical applications: Antimicrobial, antioxidant, larvicidal, anticoagulant and thrombolytic activities

This study was aimed at using hot water extracts of pod (KP), seed (KS), leaf (KL) and seed shell (KSS) of Cola nitida (kola nut) for the synthesis of nano-sized magnesium oxide and evaluation for biomedical applications. The nano-sized MgO were biosynthesized for the first time using kola nut extracts and characterized by UV–visible spectroscopy, Fourier transform infra-red spectroscopy (FTIR), transmission electron microscopy (TEM), selected area electron diffraction (SAED) and energy-dispersive X-ray (EDX). The antimicrobial, antioxidant, larvicidal, anticoagulant and thrombolytic activities of the nano-sized MgO were evaluated. The crystalline polygonal-shaped nano-sized MgO absorbed maximally in the range of 270–280 nm and FTIR spectra indicated the involvement of phenolic compounds and proteins in their biosynthesis. At 40 µg/ml, nano-sized MgO showed growth inhibition of 41.2–79.3% against eight multi-drug resistant strains of Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli and Klebsiella granulomatis, and inhibition of 60.2–88.4% on Rhizopus stolonifer, Trichoderma longibrachiatum, Aspergillus flavus and Aspergillus fumigatus. DPPH scavenging activities of 26.1–90.4% were obtained for 1–40 µg/ml of MgO nanostructures, while mortality of 13.33–100% against anopheline larvae was achieved at 30 µg/ml. The nanostructures also prevented blood coagulation and completely dissolved preformed blood clots within 10 min which is herein reported for the first time. This report has shown that Cola nitida can be employed for sustainable synthesis of nano-sized MgO with potent biomedical applications.

One-Dimensional MgO Nanostructures with Various Morphologies Grown by Thermal Evaporation Method under Atmospheric Environment

One-Dimensional MgO Nanostructures with Various Morphologies Grown by Thermal Evaporation Method under Atmospheric Environment

Synthesis of MgO nanostructure thin films via electrodeposition method for gas sensing applications

Magnesium oxide has long been intriguing due to several significant phenomena, including wide laser emission, spin electron reflectivity, and defect-induced magnetism. MgO nanostructures have a variety of applications, from spintronics to wastewater treatment, depending on their size and shape. Mg is sensitive material for hydrogen and forms MgH2, so we used Mg/MgO as a sensor to sense hydrogen gas in the present work. Magnesium oxide thin films were synthesized by electrodeposition technique using magnesium nitrate salt. XRD results suggested that the deposited thin films have a face-centered cubic structure. X-ray photoelectron spectroscopy was used to detect the elemental composition and chemical state with the general electronic structure of the sample. The morphology and growth of deposited nanostructure with elemental mapping of the thin film were investigated by SEM-EDS. The UV-visible analysis shows the calculated band gap for MgO thin filmwas 4.16 eV which is in the ultraviolet region. The I-V characteristics have been studied to find out the effect of hydrogenation on the synthesized MgO nanostructure and the sensitivity responseof about 31%. It is quiteevident that MgO nanostructure may be used for gas sensing applications (such as H2 gas). Bangladesh J. Sci. Ind. Res. 58(2), 119-128, 2023

Influence of Thickness on Some Physical Characterization for Nanostructured MgO Thin Films

MgO Nanostructured thin films with different thicknesses (200, 400, and 600 nm) have been deposited by the chemical spray pyrolysis technique. The results confirm that the structure, morphology, optical, and electrical properties were all affected by the thickness of the film. MgO films' physical properties were examined using (XRD), (FE-SEM), (EDX), (AFM), (UV-Vis spectrophotometer), and the Hall Effect. According to the structural analysis, the films have a cubic magnesium oxide polycrystalline structure, with a preferred orientation (002). The average Crystalline Size and optical band gap are found in the range (20.79-18.99) nm and (3.439-3.162) eV respectively with an increase in thickness. The surface morphology of the films reveals that they are free of crystal defects such as holes and voids, as well as homogeneous and uniform. The EDS patterns show that the as-grown films contain magnesium and oxygen. The Hall Effect shows that electrical conductivity decreases with thickness. The experimental results show that film thickness influences the physical properties of as-grown MgO thin films and that thicker films can be used as an absorber layer in solar cell applications.

Sono-assisted degradation of rhodamine B using the Fe modified MgO nanostructures: characterization and catalytic activity

Sono-assisted degradation of rhodamine B using the Fe modified MgO nanostructures: characterization and catalytic activity

Green synthesis of MgO nanoparticles and its antibacterial properties.

Magnesium oxide nanostructured particles (NP) were prepared using a simple solution combustion technique using different leaf extracts such as Mangifera indica (Mango - Ma), Azadirachta indica (Neem-Ne), and Carica papaya (Papaya-Pa) as surfactants. The highly crystalline phase of MgO nanostructures was confirmed by PXRD and FTIR studies for 2h 500°C calcined samples. To analyze the characteristics of obtained material-MaNP, NeNP, and PaNP for dosimetry applications, thermoluminescence (TL) studies were carried out for Co-60 gamma rays irradiated samples in the dose range 10-50KGy; PaNP and NeNP exhibited well-defined glow curve when compared with MaNP samples. In addition, it was observed that the TL intensity decreases, with increase in gamma dose and the glow peak temperature is shifted towards the higher temperature with the increase in heating rate. The glow peak was segregated using glow curve deconvolution and thermal cleaning method. Kinetic parameters estimated using Chen's method, trap depth (E), and frequency factor (s) were found to be 0.699, 7.408, 0.4929, and 38.71, 11.008, and 10.71 for PaNP, NeNP, and MaNP respectively. The well-resolved glow curve, good linear behavior in the dose range of 10-50, KGy, and less fading were observed in PaNP as compared with MaNP and NeNP. Further, the antibacterial activity was checked against human pathogens such as Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa. A visible zone of clearance was observed at 200 and 100μg/mL by the PaNP and NeNP, indicating the death of colonies by the nanoparticles. Therefore, PaNP nanomaterial is a potential phosphor material for dosimetry and antibacterial application compared to NeNP and MaNP.

Microwave treatment effect on the enhanced basicity of porous clay heterostructured composites derived from Laponite

Porous clay heterostructured composites (PCH) derived from layered hydrous magnesium silicate, Laponite, were functionalized by Fe(NO3)3x9H2O with the use of mechano-chemical impregnation followed by microwave irradiation or hydrothermal treatment to evoke new base properties, active in CO2 sorption. It resulted in the progressive leaching of the Mg2+ from the octahedral sheets of the Laponite structure and their capture on the surface of PCH composites increasing the Mg/Si ratio. The increase of Mg/Si ratio was accompanied by the decline of the (Mg3OH) absorption bands intensity attributed to Laponite and discussed regarding the formation of dispersed nanostructured MgO moieties capable of adsorbing CO2. CO2-TPD temperature-programmed desorption technique revealed that sorption and stabilization of CO2 molecules are related to the coordination of oxygen sites in the formed MgO lattice and that edge and corner sites facilitate the interaction of CO2 molecules with O2− sites on MgO. Doping of PCH resulted also in the nucleation of nanocrystalline α-Fe2O3 able to capture CO2 with strength and stability higher than MgO. Microwave irradiation resulted in significant development of the surface basicity as part of the transformation of clay structure. This study confirms the importance of clay minerals in the uptake and retention of CO2.

High yield synthesis and study of Cu substitution on characteristics and dielectric properties of MgO nanostructures

High-permittivity materials are becoming more popular due to the electrical and electronic industrial development. Single composition materials are well known to fall short of high permittivity requirements. So, in this article, we report pure and Cu (5%, 7%, 9%, and 11%) doped MgO nanostructures synthesized by reverse micelle method and study of their dielectric properties. Energy Dispersive Analysis of X-rays (EDAX), Powder X-ray Diffraction (PXRD), diffused reflectance UV–Vis spectroscopy (DR-UV-Vis), Dynamic Light Scattering (DLS), photoluminescence (PL), Raman spectroscopy and Broadband Dielectric Spectroscopy (BDS) are among the characterization methods used. Each synthesized sample crystallizes in cubic crystal system. As Cu doping increases from 5% to 11%, the average crystallite size dwindles from 22 to 10 nm. The bandgap is reduced from 5.71 eV to 2.58 eV as per the optical results from DR-UV-VIS spectroscopy. The intensity and surface defects are correlated by PL spectra. Raman peak shifts to the higher angle side, which is related to XRD and associated with a reduction in average crystallite size. For pure and all doping concentrations, the dielectric constant and the dissipation factor decreases with the increment in frequency which is a peculiar behaviour of dielectric materials.

Synthesis and characterization of MgO nanostructures: A comparative study on the effect of preparation route

In this study, MgO nanostructures were synthesized by five facile and diverse chemical synthesis routes, viz. precipitation (PT), sonication-precipitation (SPT), microwave combustion (MWC), conventional combustion (CC), and solvothermal (ST) processes. The influence of aforementioned synthesis routes on crystallinity, crystallite size, morphology, optical, and surface traits of MgO nanostructures was evaluated by XRD, BET, FESEM, FETEM, optical absorption, steady-state and time-resolved photoluminescence analyses. Furthermore, antioxidant and antibacterial properties of MgO nanostructures were examined. XRD analysis revealed that crystallite size and relative crystallinity (%) of MgO varied from 9 to 42 nm and 90.70–99.06%, respectively, depending on the synthesis route followed. The application of microwave irradiation (MWC) and sonication (ST) reduced particle size and increased specific surface area of MgO nanostructures compared to nanostructures obtained via CC and PT methods. This could be due to faster reaction kinetics in MWC and small-scale turbulence generated during sonication that restricts growth and agglomeration of nuclei during nanostructure synthesis. FESEM analysis revealed flake, sphere, natural rose, and marigold flower-like morphologies of MgO due to different methods followed, that can be attributed to the differences in nanostructure formation mechanism involved. The highest photoluminescence intensity observed with MgO synthesized via MWC is likely to produce a maximum number of reactive oxygen species. Consequently, MgO synthesized through MWC process showed highest bactericidal and antioxidant activities compared to MgO synthesized via other routes. Thus, present study demonstrated that properties of nanostructures required for a particular application could be customized by proper choice of the synthesis route.

Robust Smart Fabrics Composed of MgO Nanostructures Encapsulated in Hollow Polystyrene Fibers for Efficient Thermoregulation

Robust Smart Fabrics Composed of MgO Nanostructures Encapsulated in Hollow Polystyrene Fibers for Efficient Thermoregulation

Production of biodiesel from waste cooking oil using mesoporous MgO-SnO2 nanocomposite

Mesoporous, bifunctional MgO-SnO2 nanocatalysts with enhanced surface area are used for producing biodiesel from waste cooking oil. Biodiesel with yield of 80% is achieved within the first 20 min when transesterification is carried out at an optimum condition of 18:1 methanol to oil ratio, 2 wt% of nanocatalyst, and at a reaction temperature of 60 °C. The conversion gives a maximum yield of 88% when transesterification is allowed to continue for 120 min. The waste cooking oil used in this work is dominated with linoleic acid and oleic acid, which during transesterification gets converted into methyl linoleate and 9-octadecenoic acid methyl ester. These nanocatalysts are fabricated using a composite of rutile (tetragonal) phase SnO2 and cubic phase MgO nanostructures with prominent crystal orientation along [211] and [200] plane respectively. The MgO-SnO2 nanocomposites with an enhanced surface area of 31 m2/g, basic sites of 2 mmol/g, and particle size of ~15 nm are synthesized by novel sequential thermal decomposition and sol-gel technique. The synthesized wide band gap nanocomposites have Mg and Sn in the ratio of 15:1 and do not have any impurity phases as observed in the X-ray diffraction pattern and EDS spectrum. The presence of surface oxygen states and Mg2+ and Sn4+ oxidative states is responsible for the catalytic activity and recyclability displayed by the composites. This work signifies the role of nanocomposites and their synthesis conditions in improving the rate of transesterification. These metal oxide nanocomposites which are nontoxic, stable, cost effective, and easier to synthesis are promising catalysts for large-scale transesterification of waste cooking oil to biodiesel.