Binary Metal Oxides Research Articles

Effects of nano-metal oxide additives on ignition and combustion properties of MICs-boron rich fuels

Boron has been considered a promising powdered metal fuel for enhancing composite propellants' energy output due to its high energy density. However, the high ignition temperature and low combustion efficiency limit the application of boron powder due to the high boiling point of the boron oxide layer. Much research is ongoing to overcome these shortcomings, and one potential approach is to introduce a small quantity of metal oxide additives to promote the reaction of boron. This study prepared boron-rich fuels with 10 wt% of eight nano-metal oxide additives by mechanical ball milling. The effect of metal oxides on the thermo-oxidation, ignition, and combustion properties of boron powder was comprehensively studied by the thermogravimetric analysis (TG), the electrically heated filament setup (T-jump), and the laser-induced combustion experiments. TG experiments at 5 K/min found that Bi2O3, MoO3, TiO2, Fe2O3, and CuO can promote thermo-oxidation of boron. Compared to pure boron, Tonset can be reduced from 569 °C to a minimum of 449 °C (B/Bi2O3). Infrared temperature measurement in T-jump tests showed that when heated by an electric heating wire at rates from 1000 K/s to 25000 K/s, the ignition temperatures of B/Bi2O3 are the lowest, even lower than the melting point of boron oxide. Ignition images and SEM for the products further showed that the high heating rate is beneficial to the rapid reaction of boron powder in the single-particle combustion state. Fuels (B/Bi2O3, B/MoO3, and B/CuO) were mixed with the oxidant AP and ignited by laser to study the combustion performance. The results showed that B/CuO/AP has the largest flame area, the highest BO2 characteristic spectral intensity, and the largest burn rate for powder lines. To combine the advantages of CuO and Bi2O3, binary metal oxide (CBO, mass ratio of 3:1) was prepared and the test results showed that CBO can very well improve both ignition and combustion properties of boron. Especially B/CBO/AP has the highest burn rate compared with all fuels containing other additives. It was found that multi-component metal-oxide additive can more synergistically improve the reaction characteristics of boron powder than unary additive. These findings contribute to the development of boron-rich fuels and their application in propellants.

Removal of Emerging Organic Pollutants by Zeolite Mineral (Clinoptilolite) Composite Photocatalysts in Drinking Water and Watershed Water

One of the most challenging problems for people around the world is the lack of clean water. In the past few decades, the massive discharge of emerging organic pollutants (EOPs) into natural water bodies has exacerbated this crisis. Considerable research efforts have been devoted to removing these EOPs due to their biotoxicity at low concentrations. Heterogeneous photocatalysis via coupling clay minerals with nanostructured semiconductors has proven to be an economical, efficient, and environmentally friendly technology for the elimination of EOPs in drinking water and watershed water. Natural zeolite minerals (especially clinoptilolites) are regarded as appropriate supports for semiconductor-based photocatalysts due to their characteristics of having a low cost, environmental friendliness, easy availability, co-catalysis, etc. This review summarizes the latest research on clinoptilolites used as supports to prepare binary and ternary metal oxide or sulfide semiconductor-based hybrid photocatalysts. Various preparation methods of the composite photocatalysts and their degradation efficiencies for the target contaminants are introduced. It is found that the good catalytic activity of the composite photocatalyst could be attributed to the synergistic effect of combining the clinoptilolite adsorbent with the semiconductor catalyst in the heterogeneous system, which could endow the composites with an excellent adsorption capacity and produce more e−/h+ pairs under suitable light irradiation. Finally, we highlight the serious threat of EOPs to the ecological environment and propose the current challenges and limitations, before putting the zeolite mineral composite photocatalysts into practice. The present work would provide a theoretical basis and scientific support for the application of zeolite-based photocatalysts for degrading EOPs.

A Flexible Nickel-Oxide-Based RRAM Device Prepared Using the Solution Combustion Method

Binary metal oxide materials, such as nickel oxide, are widely used in flexible resistive variable memory devices due to advantages such as their easily controllable material composition, simple structural composition, and good compatibility between manufacturing processes and complementary metal oxide processes. In this work, a solution combustion method was employed to prepare NiOx thin films for use as a resistive switching layer of resistance random-access memory. The formation temperature of the NiOx layer in the RRAM device was kept as low as 175 °C, making the device compatible with flexible substrates. With polyethylene naphthalenediate as the substrate, the NiOx-based RRAM exhibited obvious bipolar resistance-switching properties, superb bending resistance, and good stability. Through theoretical fitting and structural characterization, the conduction mechanisms were attributed to the combination of the space-charge-limited current and Ohmic mechanisms, while the valence change mechanism was determined to be the resistive switching mechanism. This study demonstrates a low-temperature and scalable approach to constructing NiOx-based RRAM devices on flexible substrates.

Simple construction of gadolinium cobaltite perovskite (GdCoO3): Unveiling the dynamic electrode potential for pseudocapacitors

BackgroundThe intermittent nature of renewable energy resources has led to an ongoing mismatch between energy demands and supply in modern societies. To address this issue, the design of well-defined nanostructures with unique physicochemical nature, has emerged as a promising solution. In this regard, perovskite (ABO3) nanostructured electrode materials have shown great potential in enhancing electrochemical performance. MethodsA simple co-precipitation technique was utilized to synthesize perovskite phase gadolinium-based binary metal oxide, i.e., GdCoO3. The obtained physiochemical characterization data revealed that the GdCoO3 electrode material possessed a high surface area that facilitates the diffusion of ions and enhances its specific capacitance. Significant findingsExtensive electrochemical characterization techniques were used (cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and galvanostatic charging and discharging (GCD)) to analyze the electrochemical properties of the electrode material in this study. The charge storage mechanism of GdCoO3 was determined to be diffusion-controlled. When tested in an aqueous electrolyte (3 M KOH), GdCoO3 nano-electrode exhibited an excellent specific capacitance (519 F g–1) by a current density (1 A g–1). Furthermore, it demonstrates a significant capacitance retention rate (CRR) of 84.9 % subsequently 5000 cycles indicating its potential for long-term stability. The fabricated battery-type electrode holds promise in various applications including electric motors, flexible electronics, and energy storage devices.

Optimizing Oxygen Electrode Bifunctionality with Platinum and Nickel Nanoparticle-Decorated Nitrogen-Doped Binary Metal Oxides

Developing bifunctional oxygen electrode materials with superior activity for oxygen reduction (ORR) and oxygen evolution (OER) reactions is essential for advancing regenerative fuel cell and rechargeable metal–air battery technologies. This present work deals with the synthesis and characterization of electrocatalysts containing Pt and Ni nanoparticles supported on nitrogen-doped mixed metal oxides (Mn2O3-NiO) and the systematic evaluation of their bifunctional ORR/OER performance in an alkaline medium. These electrocatalysts have been successfully synthesized by a simple and fast microwave method. PtNi/Mn2O3-NiO-N with a binary metal oxide-to-N ratio of 1:2 demonstrated the best performance among the studied materials regarding bifunctional electrocatalytic activity (∆E = 0.96 V) and robust stability.

Facile synthesis of hybrid nanocomposite based on chitosan binary metal oxides for high‐performance supercapacitor

AbstractThe advancement in materials for energy storage for supercapacitors has been supported by the current shortage of energy as well as the increasing availability of sources of clean energy. Consequently, two‐dimensional materials based on metal oxide nanoparticles (copper oxide (CuO) and zinc oxide (ZnO), have great potential for the previously discussed utilization. A simple and affordable solid‐state approach was employed to design hybrid nanocomposite based on chitosan (Cs) blended with ZnO and CuO; this nanocomposite was labeled with CZC. The structural, morphological investigation of CZC hybrid nanocomposites, and X‐ray diffraction (XRD) of the prepared nanocomposites were characterized. Consequently, hybrid nanocomposites for application as electrodes for supercapacitor devices were developed. The hybrid nanocomposite (CZC‐3) shows improved cycle stability, high energy density, and a specific capacitance in the electrochemical activity. Remaining at 97.8% of the initial capacitance even after 5000 cycles. These results imply that the hybrid nanocomposite based on Cs/ZnO/CuO has a promising future as a supercapacitor electrode material. Additionally, it provides superior performance to other nanocomposites with a high specific capacitance of 638.3 F/g and about 86.98% capacity retention after 5000 cycles at a current density of 1 A/g.

Towards the high-throughput prediction of finite-temperature properties using the quasi-harmonic approximation

Lattice dynamics calculations within the quasi-harmonic approximation (QHA) provide an infrastructure for modelling the finite-temperature properties of periodic solids at a modest computational cost. With the recent widespread interest in materials discovery by data mining, a database of computed finite-temperature properties would be highly desirable. In this work we provide a first step toward this goal with a comparative study of the accuracy of five exchange-correlation functionals, spanning the local density approximation (LDA), generalised-gradient approximation (GGA) and meta-GGA levels of theory, for predicting the properties of ten Group 1, 2 and 12 binary metal oxides. We find that the predictions are bounded by the LDA, which tends to underestimate lattice parameters and cell volumes relative to experiments, but yields the most accurate results for bulk moduli, expansion coefficients and Grüneisen parameters, and the PBE GGA, which shows the opposite behaviour. The PBEsol GGA gives the best overall predictions of the lattice parameters and volumes whilst also giving relatively reliable results for other properties. Our results demonstrate that, given a suitable choice of functional, a variety of finite-temperature properties can be predicted with useful accuracy, and hence that high-throughout QHA calculations are technically feasible.

Amphiphilic Graft Copolymers as Templates for the Generation of Binary Metal Oxide Mesoporous Interfacial Layers for Solid-State Photovoltaic Cells.

The binary metal oxide mesoporous interfacial layers (bi-MO meso IF layer) templated by a graft copolymer are synthesized between a fluorine-doped tin oxide (FTO) substrate and nanocrystalline TiO2 (nc-TiO2). Amphiphilic graft copolymers, Poly(epichlorohydrin)-graft-poly(styrene), PECH-g-PS, were used as a structure-directing agent, and the fabricated bi-MO meso IF layer exhibits good interconnectivity and high porosity. Even if the amount of ZnO in bi-MO meso IF layer increased, it was confirmed that the morphology and porosity of the bi-MO meso IF layer were well-maintained. In addtion, the bi-MO meso IF layer coated onto FTO substrates shows higher transmittance compared with a pristine FTO substrate and dense-TiO2/FTO, due to the reduced surface roughness of FTO. The overall conversion efficiency (η) of solid-state photovoltaic cells, dye-sensitized solar cells (DSSCs) fabricated with nc-TiO2 layer/bi-MO meso IF layer TZ1 used as a photoanode, reaches 5.0% at 100 mW cm-2, which is higher than that of DSSCs with an nc-TiO2 layer/dense-TiO2 layer (4.2%), resulting from enhanced light harvesting, good interconnectivity, and reduced interfacial resistance. The cell efficiency of the device did not change after 15 days, indicating that the bi-MO meso IF layer with solid-state electrolyte has improved electrode/electrolyte interface and electrochemical stability. Additionally, commercial scattering layer/nc-TiO2 layer/bi-MO meso IF layer TZ1 photoanode-fabricated solid-state photovoltaic cells (DSSCs) achieved an overall conversion efficiency (η) of 6.4% at 100 mW cm-2.

Effect of annealing temperature on structural and electrochemical behaviour on MgFe2O4 as electrode material in neutral aqueous electrolyte for supercapacitors

Binary metal oxides possess unique structures and multiple oxidation states, making them highly valuable in electrochemical analysis. This study aims to determine the effect of annealing temperature on the electrochemical properties of magnesium ferrite when used as an electrode material in a neutral aqueous electrolyte. We utilized the sol–gel technique to synthesize the material and annealed it at various temperatures. Our analysis of the material using different characterization techniques reveals significant changes in its structural and electrochemical properties. We found that the material exhibited a range of phases, and higher annealing temperatures led to improved electrochemical properties. The electrochemical measurements showed reversible and redox pseudo-capacitance behavior, with the material annealed at 500 °C exhibiting the highest specific capacitance of 117 F g−1 at a current density of 0.5 A g−1. Capacitive and diffusion-controlled processes govern the total charge storage mechanism, and their contribution changes significantly as the annealing temperature varies. The capacitance retention of 500 °C annealed sample was 58% and it remained stable. This work establishes a correlation between annealing temperature on structural, morphological, and electrochemical behavior, thereby opening up avenues for tailoring them effectively. These findings can be useful in the development of future electrode materials for electrochemical applications.

Hollow CuCo2O4 nanocages engineered by Kirkendall effect for room-temperature sensing of ammonia gas

Recently, binary transition metal oxide (BTMO)-based gas sensors have gained significant interest in detecting harmful gases in the atmosphere. Herein, we report a p-type BTMO, hollow CuCO2O4 (CCO) nanocages, for ammonia (NH3) gas sensing at room temperature (RT). Hollow CCO nanocages were fabricated using a two-step process, including hydrothermal synthesis followed by annealing. The sensor exhibited responses of 2.8 % and 13.6 % towards 1 and 100 ppm NH3, respectively. Furthermore, it demonstrated good selectivity and repeatability for NH3 gas. Although the response decreased in the presence of humidity, it showed a high response to NH3 in a humid atmosphere. Additionally, a flexible sensor was fabricated on a PET substrate and subjected to bending (45, 90, and 190°) and twisting (30, 60, and 90°). Generally, the sensor showed a higher response after 100 cycles of bending compared to 100 cycles of twisting. Therefore, with the promising results obtained in this study, the present sensor can be used for selective RT detection of NH3 gas in flexible applications where the sensor is subjected to bending at different angles under rapid and harsh conditions.

Investigation of compound state of SiO2-TiO2 aerogel synthesized through controlled sol-gel reaction

In this work, a compound state of silica-titania aerogel was investigated through sol-gel reaction for hybridization of silica and titania with increasing reactivity by using high surface area and charge imbalances. By minimizing the sol-gel reaction rate difference and preparing a homogeneous and stable sol, a compound state of silica-titania aerogel could be obtained, without separation onto single metal oxide aerogel. The benefits of using the sol-gel synthesis method for synthesizing silica-titania compound aerogels are over a limit of substitution solubility and get binary metal oxide compound material. Diffraction and spectroscopic analyses showed that the heterogeneous linkage resulted from interaction among silicon, titanium, and oxygen ions. The coordination environment changes by the formation of an Si-O-Ti linkage following interaction among ions without phase separation on SiO2 and TiO2 aerogels. Thus, the atomically controlled sol-gel reaction can be used to design new metal-oxide-based compound aerogels and immiscible oxide materials.

Porous NiMoO4 Nanosheet Films and a Device with Ultralarge Optical Modulation for Electrochromic Energy-Storage Applications.

Reducing building energy consumption, improving aesthetics, and improving occupant privacy as well as comfort by dynamically adjusting solar radiation are important application areas for electrochromic (EC) smart windows. However, the current transition metal oxides still cannot meet the requirements of neutral coloration and large optical modulation. We report NiMoO4 nanosheet films directly grown on fluorine-doped tin oxide glasses. The as-grown NiMoO4 film not only achieves neutral coloration from transparent to dark brown but also shows an ultralarge optical modulation (86.8% at 480 nm) and excellent cycling stability (99.4% retention of maximum optical modulation after 1500 cycles). Meanwhile, an EC device demonstrating good EC performance was constructed. These results will greatly promote the research and development of binary transition metal oxides for both EC and energy-storage applications, and NiMoO4 films may be an excellent candidate to replace NiO films as ion-storage layers in complementary EC devices with WO3 films as EC layers.

Synthesis, Characterization, and Applications of ZnO, Ag2O, and ZnO/Ag2O Nanocomposites: A Review

Nanoscale dimensional materials represent a captivating area of research in modern technology, owing to their unique properties and vast potential applications. The distinct advantage of nanosized materials lies in their large surface area to volume ratio, which endows them with enhanced stability and significant functional characteristics. Among these, metal oxide nanomaterials have garnered significant attention due to their substantial energy bandgaps and high exciton binding energies, making them suitable for a wide range of applications, including antimicrobial activity and optoelectronics. This review delves into the synthesis methods of various metal oxides, emphasizing the advantages and drawbacks of physical, chemical, and biological approaches. Specifically, it focuses on the synthesis, characterization, and applications of single metal oxide nanoparticles (NPs), such as zinc oxide (ZnO) and silver oxide (Ag2O), as well as binary or composite metal oxides like ZnO/Ag2O nanocomposites. Through this comprehensive literature review, readers will gain insights into the fabrication techniques and explore the intrinsic properties of both single and composite metal oxide NPs, thereby broadening their understanding of these innovative materials and their potential technological impacts.

Machine-learning-accelerated structure prediction of PtSnO nanoclusters under working conditions.

Credible property exploration or prediction can not be achieved without well-established compositions and structures of catalysts under working conditions. We construct surrogate models via combination of machine learning (ML), genetic algorithm (GA) and ab initio thermodynamics (AITD) to accelerate global optimization of PtSn binary metal oxides, which are typically used for CO2-assisted propane dehydrogenation to propylene. This challenging case illustrates that the subtle oxidized states of PtSnO clusters can be predicted in a large chemical space including a wide range of reaction conditions. The oxidation patterns, phase diagrams and atomic charge distributions of the PtSnO clusters have been discussed. The Sn decorating mechanism to Pt in PtSnO has been explained. These results also indicate that the oxidation of PtSn clusters is more feasible under working conditions, and that previous understanding obtained only with a fully reduced PtSn alloy may be incomplete.

Redox additive effects on the electrochemical performance of hydrothermally grown, binder-free CuO nanosheets in aqueous electrolytes

Adding redox additives into the traditional electrolytes is an efficient approach to achieving high-performance binary metal oxide electrode-based supercapacitors (SCs). Herein, binder-free CuO nanosheets are developed on nickel foams via a facile hydrothermal approach, and their charge storage performance in K3[Fe(CN)6] (KFCN) redox additive electrolyte is investigated. In a three-terminal (3T) configuration, the as-prepared electrode demonstrates a remarkable capacitance of 2755 mF cm−2 (2296 F g−1) in KFCN redox additive electrolyte, which is 10 times greater than that obtained in bare KOH electrolyte (266 mF cm−2 or 222 F g−1). Further, the 93 % capacitance retention after 2000 cyclic voltammetry cycles confirms the reasonable stability of the CuO electrode for SCs with redox additives electrolyte. Additionally, the assembled CuO electrodes-based solid state symmetric supercapacitor (SSC) with redox additive gel electrolyte achieves a maximum energy density (Es) of 31.5 Wh kg−1 at a power density (Ps) of 500 W kg−1. Furthermore, red LEDs are operated by the power source of two SSCs connected in the serial mode for 130 sec. This studies imply that utilizing CuO within redox additive electrolytes could present a simple and cost-effective approach for developing high-energy storage supercapacitors.

Influence of a binary phase ZnO–CuO on the structural and reflectance properties of poly-ε-caprolactone based nanocomposites

The binary phase metal oxide of ZnO and CuO (BPMO-ZC) nanopowders were synthesized by the chemical bath deposition. The BPMO-ZC nanopowders were distributed through the poly-ε-caprolactone (PCL) matrix by solution casting. The effect of the BPMO-ZC on the structure, thermal and reflectance properties of PCL was investigated. The X-ray diffraction (XRD) confirmed the combined hexagonal wurtzite and cubic forms of the respective ZnO and CuO nanomaterials as well as an orthorhombic form of the semi-crystalline PCL nanocomposite films. Morphology included aggregated particles with heterogeneous distribution. Differential scanning calorimetry (DSC) showed that the degree of crystallinity of nanocomposites films increased in the presence of the nanopowders. Nanocomposites displayed poor thermal stability compared to PCL, but improved residue. Reflectance measurement revealed that the absorption edges of PCL shifted to higher wavelength with the addition of ZnO–CuO.

Surface reconstruction of ZSM-5 for in situ supporting cobalt tungstate catalysts toward oxidative desulfurization

Compared with homogeneous catalysts, heterogeneous catalysts have greater separability and recyclable properties. Yet, the uneven distribution of active sites in the conventional synthetic method is a challenge. Herein, ZSM-5 supported cobalt tungstate catalyst (CoWO4/ZSM-5-DR) was prepared by a facile dissolution-regrowth strategy under mild conditions. In comparison to the supported CoWO4 catalyst generated by impregnation, the catalyst demonstrated a higher desulfurization efficiency in oxidative desulfurization due to the surface structural reconstruction of ZSM-5 and the uniform dispersion of the active substances. The as-prepared CoWO4/ZSM-5-DR catalyst can achieve 100 % sulfur removal within 5 h, which exhibits good stability and a high removal rate even after 6 cycles. This work provides new insight into supported binary metal oxide catalysts with highly homogenous dispersion and effectivity.

A cyclic extrusion strategy for solvent-free synthesis of mesoporous aluminum-based metal oxide catalysts

Aluminum-based materials are an class of important solid catalysts and mechanochemical synthesis is crucial for reducing pollution and improving synthesis efficiency. Herein, we used a cyclic extrusion method to one-step synthesize a series of mesoporous alumina-based metal oxides under solvent-free conditions. The synthesized binary, ternary, and high entropy metal oxides are all mesoporous materials with high specific surface areas (200–400 m2/g). Various characterization methods are applied to illustrate the contribution of synthesis method on the pore structure, phase formation, and metal distribution. The application of alumina-based nickel catalysts with various Ni loadings in methane dry reforming reaction shows good catalytic activity and stability (100 h). The effect of Ni loadings on the coke formation is studied, and the results indicate that low nickel-loading samples show better resistance to coking.

Synthesis and characterization of transition metals (Mn, Fe, Co, Ni) doped tin oxide for magnetic and antimicrobial studies

Dilute magnetic semiconductor oxides (DMSOs) are attractive prospects for improved charge and spin degrees of freedom control. The current research presents an overview of the structural analysis and magnetic characteristics of DMSOs based on binary metal oxide nanomaterials with various ferromagnetic or paramagnetic dopants, such as Mn, Fe, Co, and Ni, which display increased ferromagnetic behaviour at ambient temperature. The co-precipitation approach was used to create nanoparticle samples of pure SnO2, Sn0.97Mn0.03O2, Sn0.97Fe0.03O2, Sn0.97Co0.03O2, and Sn0.97Ni0.03O2. The emission spectra for the high, wide emission band are 366 nm and 655 nm. Room temperature magnetic hysteresis loops for Mn, Fe, and Ni-doped SnO2 indicate ferromagnetic behaviour when compared to pure and Co-doped SnO2, with Sn0.97Mn0.03O2, Sn0.97Fe0.07O2, and Sn0.97Ni0.03O2 samples exhibiting increased coercivity and retentivity. The antibacterial activity of pure SnO2, Sn0.97Mn0.03O2, Sn0.97Fe0.03O2, Sn0.97Co0.03O2, and Sn0.97Ni0.03O2 nanoparticles was determined.

Binary metal oxide (NiO/SnO2) composite with electrochemical bifunction: Detection of neuro transmitting drug and catalysis for hydrogen evolution reaction

The synergetic effect between dual oxides in binary metal oxides (BMO) makes them promising electrode materials for the detection of toxic chemicals, and biological compounds. In addition, the interaction between the cations and anions of diverse metals in BMO tends to create more oxygen vacancies which are beneficial for energy storage devices. However, specifically targeted synthesis of BMO is still arduous. In this work, we prepared a nickel oxide/tin oxide composite (NiO/SnO2) through a simple solvothermal technique. The crystallinity, specific surface area, and morphology were fully characterized. The synthesized BMO is used as a bifunctional electrocatalyst for the electrochemical detection of dopamine (DPA) and for the hydrogen evolution reaction (HER). As expected, the active metals in the NiO/SnO2 composite afforded a higher redox current at a reduced redox potential with a nanomolar level detection limit (4 nm) and excellent selectivity. Moreover, a better recovery rate is achieved in the real-time detection of DPA in human urine and DPA injection solution. Compared to other metal oxides, NiO/SnO2 composite afforded lower overpotential (157 mV @10 mA cm−2), Tafel slope (155 mV dec−1), and long-term durability, with a minimum retention rate. These studies conclude that NiO/SnO2 composite can act as a suitable electrode modifier for electrochemical sensing and the HER.