Oxide Research Articles

Colonial Glass Beads (16th-Cent.) from Indigenous Localities of the Tamtoc Peninsula (San Luis Potosí), Mexico

We have investigated two Nueva Cádiz tubular glass beads (16th-Century) from the indigenous localities of the Tamtoc Peninsula, Huasteca Potosina (Mexico). It was part of an exceptional discovery of 96 European glass beads found in archaeological contexts of the Early Colonial period (dated 14C 1512 AD ± 30 years, before 1560 AD). They correspond typologically to the Kidd's typology's colour variants IIIc1 and IIIc2. These multilayered beads are made from a gob formed by three successive dips, then blown up, drawn, and hot-formed before being sectioned. PIGE/PIXE (Particle-induced Induced Gamma and X-Ray Emissions) and Raman spectroscopy analyses reveal that the glass type is an ashes soda-lime-silica glass. Trace elements associated with the metal oxides used to tint and opacify these glasses are also significant. The outer layer of both types is blue-coloured by copper oxide while a mixture of tin and lead oxides opacifies the middle layer in white through cassiterite (SnO2) formation. As, Ni, Bi, and U contents reveal this cobalt, mixed with manganese, which colours the inner layer of type IIIc1 beads in purple, comes from the Freiberg mine in Southeastern Germany (Saxony). Compared with other Pan-American finds from the same period, these Mexican Nueva Cádiz beads have similar chemical compositions to specimens discovered in the colonial city ‘ruins of Nueva Cádiz (Cubagua Island, Venezuela). Finally, we question 16th-Century texts on how Mesoamerican peoples might have culturally perceived these blue beads made with a material unknown to them. By studying Mexico's colonial history, we propose several Spanish expeditions that may have introduced these beads to the Huasteca.

Utilization of Plant based Nanoparticles Emerging in Nano-biomedical Science to Target Drug Deliveries for Breast Cancer Treatment: Existing Work and Future Need

Abstract: Cancer is a major global health concern and a hereditary disease brought on by alterations in the genetic code that controls how cells behave. In the United States and other countries, breast cancer is very common among females. Through the development of innovative biocompatible Nanocomposites for therapy, which demonstrate a highly appropriate manner of nanoparticles, Nanomedicine offers incredible potential to develop cancer treatment and diagnosis. More than 60% of anticancer medications on the market today are derived from natural sources. Historically, plants have been used to treat a wide range of illnesses, including cancer. This work aimed to treat breast cancer with plant-based nanoparticles. The information was gathered from research that has already been published on Google Scholar, PubMed, and Web of Science. Different nanoparticles have been shown to be effective drug delivery agents to treat breast cancer. These include gold, silver, platinum, iron, zinc oxide, copper nanoparticles, and other metals, such as nickel, manganese, silica, titanium, palladium, cerium, and platinum. It was discovered that all metal preparation nanoparticles have an effective function in the treatment of infectious diseases and cancer. In conclusion, the characteristics of biomolecules included in plant extracts may be connected to the greenproduced NPs. Because of their high effectiveness, plant based NPs synthesis will be necessary in the future to treat breast cancer.

Cu-ZnO Embedded in a Polydopamine Shell for the Generation of Antibacterial Surgical Face Masks.

A new easy protocol to functionalize the middle layer of commercial surgical face masks (FMs) with Zn and Cu oxides is proposed in order to obtain antibacterial personal protective equipment. Zinc and copper oxides were synthesized embedded in a polydopamine (PDA) shell as potential antibacterial agents; they were analyzed by XRD and TEM, revealing, in all the cases, the formation of metal oxide nanoparticles (NPs). PDA is a natural polymer appreciated for its simple and rapid synthesis, biocompatibility, and high functionalization; it is used in this work as an organic matrix that, in addition to stabilizing NPs, also acts as a diluent in the functionalization step, decreasing the metal loading on the polypropylene (PP) surface. The functionalized middle layers of the FMs were characterized by SEM, XRD, FTIR, and TXRF and tested in their bacterial-growth-inhibiting effect against Klebsiella pneumoniae and Staphylococcus aureus. Among all functionalizing agents, Cu2O-doped-ZnO NPs enclosed in PDA shell, prepared by an ultrasound-assisted method, showed the best antibacterial effect, even at low metal loading, without changing the hydrophobicity of the FM. This approach offers a sustainable solution by prolonging FM lifespan and reducing material waste.

Electroplating sludge derived CuFe2O4/MgFe2O4 metal oxide composites for highly efficient removal of Congo red

Electroplating sludge derived CuFe2O4/MgFe2O4 metal oxide composites for highly efficient removal of Congo red

Benchmarking Metal Oxide Electrocatalysts for Oxygen Reduction

Benchmarking Metal Oxide Electrocatalysts for Oxygen Reduction

Mean-field homogenization of liquid metal elastomer composites: comparative study and exact dilute solution of core–shell inclusion

Liquid metal-elastomer composites (LMECs) have gathered significant attention for their potential applications in various functional stretchable devices, with inclusion sizes ranging from micrometers to nanometers. These composites exhibit exceptional properties, such as high electric permittivity and thermal conductivity, surpassing those of the elastomer matrix, thus enabling a broader range of applications without compromising the material's stretchability. To investigate the diverse effective elastic and functional properties of LMECs, micromechanics-based homogenization method based on Eshelby's inclusion solution are invaluable. However, the extreme contrast in elastic constants among the phases in LMECs, particularly for nanosized inclusions where a considerable amount of stiff metal oxide forms around the inclusions, can lead to critical failure in predicting effective properties if inadequate homogenization approach is employed. In this study, we present multiple mean-field homogenization approaches applicable to LMECs with core-shell morphology, namely: (i) multi-phase, (ii) sequential, (iii) pseudo-grain, and (iv) direct approaches. We compare the accuracy of the models concerning effective elastic, thermal, and dielectric properties, evaluated against numerical homogenization results and compared with reported experimental data. Specifically, we highlight homogenization scheme utilizing exact field solutions of dilute core-shell inclusion, emphasizing the importance of accurately capturing the field in the micromechanics of LMECs. Furthermore, we demonstrate that widely utilized interphase model could not properly resolve the core-shell morphology and thus should be avoided. This comprehensive assessment provides critical insights into the proper homogenization strategies for designing advanced LMECs with precise prediction of effective properties.

Dewetting-driven printing of thin metal oxide films

Dewetting-driven printing of thin metal oxide films

Co/Cu/C multi-doped VOx composite nanobelts for aqueous asymmetric supercapacitors

VOx, possessing multiple stable oxidation states, demonstrates high theoretical capacity, rendering it a promising candidate for supercapacitor electrodes. However, its practical capacity and cyclic performance are hindered by low electrical conductivity and sluggish diffusion kinetics. Incorporating heteroatoms into transition metal oxides has emerged as an effective approach to mitigate these challenges. Nonetheless, the reported capacities and cyclic stabilities of single-element-doped-VOx as supercapacitor electrodes remain unsatisfactory. Herein, we propose a Co/Cu/C multi-doped VOx composite (VCoCuC) nanobelts, which significantly boosts the specific capacity (5.96 C cm−2/398.6 C g−1 @ 10 mA cm−2) and cycling performance (97.1% of the initial capacity after 2,000 cycles @ 60 mA cm−2) compared to samples with only Co/Cu, Co/C, or Cu/C doping. The possible functions of each doping element are discussed. Additionally, an aqueous asymmetric supercapacitor with VCoCuC as the cathode and conductive carbon cloth (CC) as the anode is assembled to demonstrate the potential application of VCoCuC, which delivers high energy density and excellent cyclic performance. These findings highlight the potential for improving the practical capacity and cyclic performance of VOx electrodes via a multi-doping strategy.

Seidlitzia rosmarinus as a multipurpose environmentally friendly alkali in simultaneous dyeing and nanofinishing of polyester fabric: ZnO-NPs synthesis, carrier-free dyeing, and reduction clearing

A multipurpose product could be produced by synthesizing metal oxides and dyeing the fabric. However, to achieve better, cleaner results while consuming less energy, it is ideal to shorten the time and reduce costs by simultaneously creating nanoparticles and dyeing. This work facilitates carrier-free dyeing of polyester fabric and the synthesis of ZnO-NPs using Kelyab as a green alkali. The remarkable results demonstrated reduced bending length, i.e., a softer handle, higher air permeability, and tensile strength, longer resistance in alkaline conditions, and comparable color strength and fastness. Moreover, the after-treatment, the last treatment step on the finished or dyed fabric, pertains to the reduction clearing. It is essential for dyed PET fabric, given its significance in colorimetric characteristics and other fastness attributes, particularly washing. Thus, it is necessary to develop innovative techniques to achieve these objectives without using harmful chemicals. Kelyab, as an environmentally safe reducing agent, produced comparable results to those of the conventional method, especially in color strength. In addition, air plasma was applied as a surface activation and green pre-treatment, resulting in the highest color and tensile strength. The prepared samples were examined using FT-IR, XRD, and FESEM, among other tests. Using fewer chemicals (50% lower) in the reduction clearing, saving time and energy for preparing reduction solution, and lowering the requirement for waste-water treatment in the simultaneous nanosynthesis and dyeing are the novelties of the introduced processing that can replace conventional method in dyeing, post-dyeing, and nanofinishing treatments.

Theoretical Model for Determining the Thickness and Optical Constants of Transparent Conducting Oxide Thin Films From the Measured Reflectance Spectra

ABSTRACTThickness and optical constants of transparent conducting oxide (TCO) of metal oxide thin films have been commonly estimated by invoking theoretical models based on measured optical reflectance or transmittance. One of such widely employed models is reflectance‐based Kushev model. However, the relatively higher value of the absorption coefficient at the absorption edge of TCOs of metal oxide thin films results in a large deviation of their thickness values estimated by this model. To address the underlying problems, in the present work, we have improved the Kushev model. Specifically, for minimizing the error in the estimated thickness values from the proposed model, we have employed t test for discarding outliers of a set of thickness values of a given thin film, which were calculated from nearby extrema of a reflectance curve. Then the thickness calculated from model was validated by comparing the value of ZnO thin transparent films extracted from ellipsometric measurement. Our model shows excellent agreement with the thickness values of ZnO films from ellipsometric measurement with only 1.2% deviation. Furthermore, observed values were also compared with the values from already established Cauchy model. The perfectly matching of the simulated reflectance spectra from the present model with the measured reflectance and excellent agreement of thickness values derived from the ellipsometric measurements with the values extracted from the model may infer us that the present model is suitable for fairly accurately estimating film thicknesses of TCO thin films.

Optimization of MOSFET Copper Clip to Enhance Thermal Management Using Kriging Surrogate Model and Genetic Algorithm

Metal–oxide–semiconductor field-effect transistors (MOSFETs) are critical in power electronic modules due to their high-power density and rapid switching capabilities. Therefore, effective thermal management is crucial for ensuring reliability and superior performance. This study used finite element analysis (FEA) to evaluate the electro-thermal behavior of MOSFETs with copper clip bonding, showing a significant improvement over aluminum wire bonding. The aluminum wire model reached a maximum temperature of 102.8 °C, while the copper clip reduced this to 74.6 °C. To further optimize the thermal performance, Latin Hypercube Sampling (LHS) generated diverse design points. The FEA results were used to select the Kriging regression model, chosen for its superior accuracy (MSE = 0.036, R2 = 0.997, adjusted R2 = 0.997). The Kriging model was integrated with a Genetic Algorithm (GA), further reducing the maximum temperature to 71.5 °C, a 4.20% improvement over the original copper clip design and a 43.8% reduction compared to aluminum wire bonding. This integration of Kriging and the GA to the MOSFET copper clip package led to a significant improvement in the heat dissipation and overall thermal performance of the MOSFET package, while also reducing the computational power requirements, providing a reliable and efficient solution for the optimization of MOSFET copper clip packages.

Bimetallic MOFs-Derived Metal Oxides Co3O4/SnO2 Microspheres for Ultrahigh Response n-Butanol Gas Sensors.

The construction of p-n heterojunctions is expected to be one of the effective means to improve gas sensitivity. In this research, p-n heterojunctions are successfully constructed by metal oxides derived from metal-organic frameworks (MOFs). MOFs-derived bimetallic Co3O4/SnO2 microspheres are prepared by precipitation. Gas-sensing performance shows that the Co3O4/SnO2 sensor exhibits an extremely high response (Ra/Rg = 641) to 20 ppm of n-butanol at 200 °C, which is 19 times that of pristine SnO2. It can detect n-butanol gas at low concentrations, has good selectivity to alcohol gas, and reduces the interference of benzene gas. The improved gas sensitivity can be attributed to the formation of a stable heterojunction between Co3O4 and SnO2, resulting in a greater resistance change of Co3O4/SnO2. Co3O4/SnO2 inherits the characteristic of high specific surface area of MOFs, which provides abundant sites for the reaction of the target gas and oxygen molecules. Finally, the gas-sensing mechanism of the Co3O4/SnO2-based sensor is discussed in detail.

Facet-Engineered BiVO4 Photocatalysts for Water Oxidation: Lifetime Gain Versus Energetic Loss.

A limiting factor to the efficiency of water Oxygen Evolution Reaction (OER) in metal oxide nanoparticle photocatalysts is the rapid recombination of holes and electrons. Facet-engineering can effectively improve charge separation and, consequently, OER efficiency. However, the kinetics behind this improvement remain poorly understood. This study utilizes photoinduced absorption spectroscopy to investigate the charge yield and kinetics in facet-engineered BiVO4 (F-BiVO4) compared to a non-faceted sample (NF-BiVO4) under operando conditions. A significant influence of preillumination on hole accumulation is observed, linked to the saturation and, thus, passivation of deep and inactive hole traps on the BiVO4 surface. In DI-water, F-BiVO4 shows a 10-fold increase in charge accumulation (∼5 mΔOD) compared to NF-BiVO4 (∼0.5 mΔOD), indicating improved charge separation and stabilization. With the addition of Fe(NO3)3, an efficient electron acceptor, F-BiVO4 demonstrates a 30-fold increase in the accumulation of long-lived holes (∼45 mΔOD), compared to NF-BiVO4 (∼1.5 mΔOD) and an increased half-time, from 2 to 10 s. Based on a simple kinetic model, this increase in hole accumulation suggests that facet-engineering causes at least a 50-100 meV increase in band bending in BiVO4 particles, thereby stabilizing surface holes. This energetic stabilization/loss results in a retardation of OER relative to NF-BiVO4. This slower catalysis is, however, offset by the observed increase in density and lifetime of photoaccumulated holes. Overall, this work quantifies how surface faceting can impact the kinetics of long-lived charge accumulation on metal oxide photocatalysts, highlighting the trade-off between lifetime gain and energetic loss critical to optimizing photocatalytic efficiency.

Photocatalytic degradation of naphthalene, using various nanocomposite materials mostly based on metal oxides

Photocatalytic degradation of naphthalene, using various nanocomposite materials mostly based on metal oxides

Controlled synthesis of Co–Ni3Se2/MoS2/Ni3S2 nanoarrays as robust electrocatalyst for urea and seawater oxidation reaction

Hydrogen production through electrolysis of water is becoming more and more prominent in the preparation of renewable energy, but the shortage of traditional electrolyte forces us to search for brand new electrolytes. And urea and seawater, which are in large reserves and easily accessible, have become the mainstream electrolytes for hydrogen production. This paper reported the successful preparation of Co-doped Ni3Se2 heterostructured catalysts with MoS2 and Ni3S2 heterogeneous structure in details by selenization and sulfidation of reactive metal oxides with hydroxide precursors. The Co–Ni3Se2/MoS2/Ni3S2 target compounds showed excellent performance in the urea oxidation reaction (UOR), requiring only the potential of 1.281 V at a current density of 10 mA∗cm−2 comparing with other catalysts while possessing a smaller Tafel slope as well as a larger double-layer capacitance, which was also reflected in impedance spectra. The result indicated that the target catalysts possessed a good urea oxidation reaction performance in all aspects. The oxygen evolution reaction (OER) performance also performed equally well in seawater electrolyte, a current density of 10 mA∗cm−2 was achieved with only overpotential of 164 mV. It should be noted, however, that the material was not stable in the urea and seawater tests, and further optimization work is needed to improve the stability of the electrode. The adsorption energies of the electrode components for urea molecules were analyzed by Density Functional Theory (DFT) calculations to further reveal the importance of the heterogeneous structure of the electrode during the UOR reaction.

Fire retardancy of epoxy composites: A comparative investigation on the influence of porous structure and transition metal of metal-organic framework

Metal-organic frameworks (MOFs) are crystalline porous materials constructed by metal nodes and organic linkers. A series of key features such as high surface area, catalytic performance provide a platform for preparing MOF-based fire retardants (FRs). However, understanding the role of the porous structure and catalytic metal species remains a key issue towards the fire retardant mechanism of MOFs. This work systematically studied the difference between the performance of a zirconium based MOF(UiO-66), its derived porous zirconium oxide (U-ZrO2), and commercial ZrO2 (C-ZrO2), in imparting fire retardancy, suppressing smoke and charring property towards epoxy. With the presence of 3 wt% porous U-ZrO2, EP/3U-ZrO2 sample showed better performance in suppressing heat (10 % reduction) and toxic carbon monoxide (14 % reduction) than that of EP/3C-ZrO2 due to the “tortuous path” effect and formation of a compact char. Moreover, a greater number of exposed catalytic sites on MOF compared with thermally treated metal oxide significantly reduced total smoke production (TSP) of the EP/MOF sample by 38 %. Catalytic carbonization attributed to the great number of metal sites on MOF is crucial in providing compact char residue, thereby suppressing smoke for EP. In perspective, this work opens a window for understanding the fire retardant mechanism of MOF-based FR towards polymers.

Catalytic oxidation of butylated hydroxytoluene using thermally treated cobalt-copper layered double hydroxides: Synthesis, structural evolution, and mechanistic insights

This study investigates the application of cobalt-copper layered double hydroxides (LDHs) in the oxidation of butylated hydroxytoluene (BHT) and explores their catalytic behavior during thermal treatment. LDHs were synthesized via coprecipitation, and various ratios of Co-Cu hydrotalcite were subjected to thermal treatment. Structural analysis revealed that thermal treatment transforms the LDHs into mixed metal oxides. Among the synthesized catalysts, Co1Cu3-LDHs exhibited superior catalytic activity in the oxidation of BHT. Techniques such as XRD, FT-IR, TGA, N2 adsorption-desorption, SEM, and XPS were employed to investigate the structural changes and surface properties of the LDHs. The Co1Cu3-LDH catalyst, treated at 250 °C, exhibited outstanding catalytic performance, attributed to the synergistic effects between Co and Cu. Upon optimizing the reaction conditions, the conversion of BHT reached 99 %, with a selectivity of 77 % towards 3,5-di‑tert‑butyl‑4-hydroxybenzaldehyde (BHT-CHO). The oxidation mechanism involves the oxidation of the π-electron system on the benzene ring and deep oxidation of the phenolic hydroxyl methyl group, with two potential reaction pathways proposed.

Aqueous extract of CAP-ash: A greener benchmark for Suzuki-Miyaura coupling reaction in palladium catalyzed ligand-free condition

Synthesis, molecular, spectroscopic properties, and electronic structure calculations of biphenyls derivatives have been achieved using a highly efficient catalytic amount of Pd(OAc)2 in aqueous extract of custard apple peels (CAP)-ash (AECAP) a green, highly cost-effective, operationally convenient and environmentally benign media at ambient temperature. The analytical reports showed the presence of metal oxides which are probably extracted in water produces corresponding hydroxides, which provide alkaline media in water which shows dual performance (solvent and base) for said cross-coupling transformation. The catalytic system is generated in situ based on aqueous extract and Pd(OAc)2 which requires no external base and ligand. Moreover, the study also offers insights into the frontier molecular orbitals (FMO), electronegativity, chemical potential, global electrophilicity index, ionization potential, electron affinity, chemical hardness, and softness properties of the synthesized biphenyl derivatives for understanding their stability, active sites, and biological activity using density functional theory (DFT) at the B3LYP/6–311G(d,p) level/basis.

Nanomaterials for Plant Disease Diagnosis and Treatment: A Review.

Currently, the excessive use of pesticides has generated environmental pollution and harmful effects on human health. The controlled release of active ingredients through the use of nanomaterials (NMs) appears to reduce human exposure and ecosystem alteration. Although the use of NMs can offer an alternative to traditional methods of disease diagnosis and control, it is necessary to review the current approach to the application of these NMs. This review describes the most recent and significant advances in using NMs for diagnosing and treating plant diseases (bacteria, phytopathogenic fungi, viruses, and phytopathogenic nematodes) in cultivated plants. Most studies have focused on reducing, delaying, or eliminating bacteria, fungi, viruses, and nematodes in plants. Both metallic (including metal oxides) and organic nanoparticles (NPs) and composites are widely used in diagnosing and controlling plant diseases due to their biocompatibility and ease of synthesis. Few studies have been carried out with regard to carbon-based NPs due to their toxicity, so future studies should address the development of detection tools, ecological and economic impacts, and human health. The synergistic effect of NMs as fertilizers and pesticides opens new areas of knowledge on the mechanisms of action (plant-pathogen-NMs interaction), the interaction of NMs with nutrients, the effects on plant metabolism, and the traceability of NMs to implement sustainable approaches. More studies are needed involving in vivo models under international regulations to ensure their safety. There is still controversy in the release of NMs into the environment because they could threaten the stability and functioning of biological systems, so research in this area needs to be improved.

Prediction of catalytic performance of metal oxide catalysts for alkyne hydrogenation reaction based on machine learning

In the field of catalyst design, machine learning is gaining significant attention, especially in situations where data is limited. Facing this challenge, we have developed a neural network model that enhances predictive accuracy through the careful selection of catalyst descriptors and feature engineering, aiming to predict the conversion rate and selectivity of the acetylene semi-hydrogenation reaction. Our model has identified promising metal oxide catalysts, such as CuO, ZnO, and V2O5, for the acetylene semi-hydrogenation reaction, and these predictions have been experimentally validated. Among them, CuO achieved an acetylene conversion of 99.6 % and an ethylene selectivity of 90 % at 50–100°C, which is unprecedented at the reaction space velocity we tested. This high activity at relatively low temperatures indicates a more promising industrial application. Looking ahead, machine learning will play a pivotal role in catalyst design, accelerating the discovery and industrial application of new materials.