Synthesis Of Metal Oxides Research Articles

Facilitating Electrochemical Ozone Production and Chlorine Evolution Reaction by Synergistic Effect of Multicomponent Metal Oxides

AbstractThe concomitant degradation of organic contaminants using green oxidants, NaClO and O3, exhibits great potential to mitigate the deleterious impact of organic pollutants. In this work, the electrochemical ozone production (EOP) and chlorine evolution reaction (CER) performed by highly active electrocatalysts composed of Ce‐Ni‐Sb‐SnO2 and Ru‐Ir‐Ce‐Ni‐Sb‐SnO2, respectively, are presented. Ce‐Ni‐Sb‐SnO2 exhibits high selectivity with a 43.9% Faraday efficiency in EOP. Incorporating Ru and Ir in Ru‐Ir‐Ce‐Ni‐Sb‐SnO2 improves CER performance, achieving outstanding Faraday efficiency of up to 98.3%. Additionally, it achieves a low overpotential of ≈80 mV at 10 mA cm−2 with 0.3 m NaCl (pH = 6). Theoretical calculations reveal the significant impact of multicomponent oxides on reaction intermediate adsorption. Ce, Ni, Sb doping on SnO2 enhances O2 and O3 adsorption for optimal EOP performance, while Ru and Ir doping on Ce‐Ni‐Sb‐SnO2 enhances Cl adsorption, boosting CER performance. Further investigations into the decomposition of pesticides and antibiotics demonstrate that the collaborative impact of O3 and NaClO elicits a significantly more robust kinetic degradation rate in comparison to their individual influences. This work aims to shed light on the synthesis of multicomponent metal oxides as potential precursors for the cost‐effective preparation of O3 and NaClO for electrochemical advanced oxidation processes.

Biosynthesis of CuO/Cu2O-ZnO nanocomposites via Commelina benghalensis leaf extract and their antibacterial, photocatalytic and antioxidant assessment

This research paper presents the antibacterial, photocatalytic, and antioxidant applications of biologically synthesized CuO/Cu2O-ZnO (90:10, 80:20, 70:30, and 60:40) nanocomposites synthesized using Commelina benghalensis leaf extract. The rod-shaped and coral reef-like morphology was characterized using advanced imaging techniques like transmission electron microscopy (TEM), scanning electron microscopy (SEM). X-ray diffraction (XRD) spectroscopy revealed average size of poly-crystalline structures from 4.17 to 6.39 nm. TEM also analyzed average particle size of 8–25 nm. The energy band gap values are measured between 2.51 and 3.11 eV from UV–Visible spectroscopic technique. The antibacterial activity of the nanocomposites was determined against pathogenic bacteria, Staphylococcus aureus, Escherichia coli and Bacillus subtilis, and the results showed significant inhibition of bacterial growth. The antioxidant activity of the nanocomposites was evaluated using ascorbic acid as a standard, and the results upto 97.53 % scavenging indicated their potential use as natural antioxidants. The photocatalytic activity of the nanocomposites was investigated by degrading organic pollutants, methyl orange and methylene blue upto 97.63 and 96.23 %, respectively, under visible light irradiation. The results showed the efficient degradation of pollutants by the nanocomposites, indicating their potential in environmental remediation. Overall, this study demonstrates the promising applications of biologically synthesized metal oxide nanocomposites in various fields, including medicine, food packaging, and environmental remediation. These findings could pave new insights into the morphology-dependent applications of biologically synthesized nanocomposites.

Enhancements of Structural and Optical Properties of MgO: SnO2 Nanostructure Films

This study investigates the structural and optical properties of MgO:SnO2 nanoparticles using the Chemical precipitation method, The thin films were deposited by the spin coating technique on glass substrates. X-ray diffraction analysis proved the crystalline structure of prepared thin films, with the peaks corresponding to the (110), (101), (200), (211), and (220) planes, with the tetragonal SnO2 crystal structure, Fourier transforms infrared (FTIR), and scanning electron microscope (SEM) used to characterize the functional groups, shape, and dimensions of synthesized metal oxide nanoparticles. The optical properties of the films were studied by UV-Vis spectroscopy, and the bandgap energy was estimated to be in the range of (3.9 - 3.4 eV). The refractive index and extinction coefficient of the films were also determined, and the results indicated that the films had good transparency in the visible region, The study concludes that MgO:SnO2 thin films obtained by spin coating technique have potential applications in optoelectronics and gas sensors.

A “Green” Reaction Cycle Pathway for Synthesizing Metal Oxide Quantum Dots

Synthesis of highly stable quantum dots (QDs) is always a challenge for researchers in nanomaterial community because of involved complexities of the process time and steps. In the past few years, we have demonstrated a simple and single step synthesis process for a range of metal oxide (MO) QDs using plasma-induced non-equilibrium electrochemistry (PiNE).1 , 2 , 3 PiNE is a new and emerging technique based on electrochemical process taking place in liquids from plasma interaction.4 This method is rapid and produces highly stable QDs starting from a metal foil and ethanol as electrolyte. As MO QDs semiconductors in general are a promising candidate for energy harvesting application mainly from their nanoscale effects.5 , 6 In this work, we will present the general applicability of this method for a range of metal oxides and the provide more an in-depth case study for CuO QDs providing details of the reaction mechanisms. An extensive analysis of the solution along with the quantum dots was carried out with nuclear magnetic resonance (NMR) spectroscopy and gas chromatography-mass (GC-MS) spectroscopy, Fourier transform infra-red spectroscopy (FTIR) and ultraviolet-visible (UV-Vis) spectroscopy, pH and the plasma-ethanol interface using optical emission spectroscopy. Thus, the study discloses important aspects of plasma interactions with a non-aqueous medium particularly the trace products and QD purity shows the entire process is a ‘green’ synthesis cycle.7 Reference (1) Ni, C.; Carolan, D.; Rocks, C.; Hui, J.; Fang, Z.; Padmanaban, D. B.; Ni, J.; Xie, D.; Maguire, P.; Irvine, J. T. S.; Mariotti, D. Microplasma-Assisted Electrochemical Synthesis of Co 3 O 4 Nanoparticles in Absolute Ethanol for Energy Applications. Green Chem. 2018, 20 (9), 2101–2109. https://doi.org/10.1039/C8GC00200B.(2) Ni, C.; Carolan, D.; Hui, J.; Rocks, C.; Padmanaban, D.; Ni, J.; Xie, D.; Fang, Z.; Irvine, J.; Maguire, P.; Mariotti, D. Evolution of Anodic Product from Molybdenum Metal in Absolute Ethanol and Humidity Sensing under Ambient Conditions. Cryst. Growth Des. 2019, 19 (9), 5249–5257. https://doi.org/10.1021/acs.cgd.9b00646.(3) Chakrabarti, S.; Carolan, D.; Alessi, B.; Maguire, P.; Svrcek, V.; Mariotti, D. Microplasma-Synthesized Ultra-Small NiO Nanocrystals, a Ubiquitous Hole Transport Material. Nanoscale Adv. 2019. https://doi.org/10.1039/C9NA00299E.(4) Mariotti, D.; Patel, J.; Švrček, V.; Maguire, P. Plasma-Liquid Interactions at Atmospheric Pressure for Nanomaterials Synthesis and Surface Engineering. Plasma Process. Polym. 2012, 9 (11–12), 1074–1085. https://doi.org/10.1002/ppap.201200007.(5) Velusamy, T.; Liguori, A.; Macias-Montero, M.; Padmanaban, D. B.; Carolan, D.; Gherardi, M.; Colombo, V.; Maguire, P.; Svrcek, V.; Mariotti, D. Ultra-Small CuO Nanoparticles with Tailored Energy-Band Diagram Synthesized by a Hybrid Plasma-Liquid Process. Plasma Process. Polym. 2017, 14 (7), 1600224. https://doi.org/10.1002/ppap.201600224.(6) McGlynn, R.; Chakrabarti, S.; Alessi, B.; Moghaieb, H. S.; Maguire, P.; Singh, H.; Mariotti, D. Plasma-Induced Non-Equilibrium Electrochemistry Synthesis of Nanoparticles for Solar Thermal Energy Harvesting. Sol. Energy 2020, 203 (April), 37–45. https://doi.org/10.1016/j.solener.2020.04.004.(7) Padmanaban, D. B.; McGlynn, R.; Byrne, E.; Velusamy, T.; Swadźba-Kwaśny, M.; Maguire, P.; Mariotti, D. Understanding Plasma–Ethanol Non-Equilibrium Electrochemistry during the Synthesis of Metal Oxide Quantum Dots. Green Chem. 2021, 23 (11), 3983–3995. https://doi.org/10.1039/D0GC03291C.

Exploring the Antibacterial Potential of Green-Synthesized MgO and ZnO Nanoparticles from Two Plant Root Extracts.

The green approach-based nanoparticle synthesis is considered a more cost-effective and ecologically responsible method of producing nanoparticles than other standard techniques. A major accomplishment in resolving these issues is the use of nanoparticles for environmental pollution remediation. This article describes a simple method for producing MgO and ZnO nanoparticles (NPs) using aqueous extracts of Zingiber officinale and Glycyrrhiza roots as the stabilizing and reducing agents, respectively. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersed X-ray (EDX) spectroscopy methods were used to characterize the biologically synthesized metal oxide nanoparticles (MO NPs). The XRD results showed that the mean crystallite sizes of synthesized ZnO and MgO NPs, which have excellent purity, are 12.35 nm and 4.83 nm, respectively. The spherical or elliptical shape of the synthesized NPs was confirmed by the SEM analysis. The antibacterial activity of the synthesized NPs against both Gram-negative and Gram-positive bacteria was thoroughly investigated. With a medium zone of inhibition of 7 to 10 mm, the as-synthesized MgO NPs and ZnO NPs demonstrated moderate antibacterial activity towards various bacterial strains.

Double‐Carbon‐Layer Core–Shell Complex Sulfides Derived from Bimetallic Metal–Organic Frameworks for Li‐/Na‐Ion Battery Storage

Metal–organic frameworks (MOFs) have been extensively studied due to their porous structures and large specific surface areas. Its unique combination of central metal and organic ligand has become a common precursor for the synthesis of metal phosphides, selenides, oxides, and sulfides. However, the carbonaceous structure derived from some MOF materials is still not enough to perfectly alleviate the negative impact of the volume change of metal sulfides. Herein, bimetallic MOF (Zn‐Co‐ZIF) is used as a precursor, coated with dopamine hydrochloride, and then calcined and gas‐phase vulcanized to prepare ZnS/CoS2‐C@NC with a double‐carbon‐layer core–shell structure. The existence of the two carbonaceous structures can not only improve the electron transport ability, but also play an important role in alleviating the volume expansion caused by metal sulfides during repeated charging and discharging. Due to its stable carbon layer structure, ZnS/CoS2‐C@NC has a higher specific capacity (1175.4 mAh g−1 in lithium‐ion batteries (LIBs) and 430.9 mAh g−1 in sodium‐ion batteries after 100 cycles at a current density of 0.2 A g−1 respectively) and excellent rate capability (338.2 mAh g−1 specific capacity maintained after 2000 cycles at a current density of 5 A g−1 in LIBs).

Initial interpretation of Laser-induced Incandescence (LII) signals from flame-generated TiO2 particles: Towards a quantitative characterization of the flame synthesis processes

Among various optical diagnostics for the characterization of particle formation in flames, laser-induced incandescence (LII), developed for soot particles, is attracting attention for the study of flame synthesis of metal-oxides. Among them, TiO2 nanoparticles are widely used for pigments and photocatalysts. Recent works have shown the feasibility of LII for flame-synthesized TiO2, but extensive research is still needed to quantitatively characterize TiO2 production in flames with LII measurements. In this work, the first attempt towards the characterization of TiO2 synthesis in flames is provided as a normalized volume fraction. To achieve this, TiO2 nanoparticles are generated in a laminar coflow diffusion flame of argon-diluted hydrogen and air with pre-vaporized titanium isopropoxide (TTIP). A 355 nm laser is used to irradiate the flame-generated particles. Spectral, temporal, and spatial measurements are performed at various flame heights. First, laser-induced emission (LIE) at prompt is investigated for different laser fluences to identify the operating conditions that ensure the LII-like nature of the measured signals. The LIE at high fluence presents sharp features that contain information on the atomic composition of the particles and of the vaporized species when compared to reference spectra of carbon black and high-purity TiO2 particles. Then, the LII signal at lower fluence is used to obtain an estimation of the spatial evolution of the normalized volume fraction and of the LII signal decay time. These results are finally used to discuss the major aerosol processes along the flame centerline.

Plasma dynamic synthesis of dispersed metal oxide materials in CO2 medium

The steadily high interest in metal oxides, including in the form of fine powders, has led to a rapid increase in their production, the search for new synthetic methods and the expansion of possible applications. CO2 has proven itself as a cheap and abundant source of mild oxidant, which can potentially be used for oxidation reactions. However, the key problem of CO2 application is the necessity to break the bonds of the CO2 molecule that requires a large amount of energy. This work presents a fundamentally new approach for metal oxide synthesis, when applying CO2 as a gaseous precursor and oxidant, based on application of a pulsed arc discharge plasma of the electroerosion type. The implementation of the proposed method called plasma dynamic synthesis results in obtaining dispersed metal oxides that is demonstrated by the examples of Cu–O, Fe–O, Ti–O and Al–O systems. The influence of the metal-containing plasma type and operation modes on the formation of metal-oxide dispersed materials is studied. The multi-pulse operation mode in the considered system with titanium and aluminum electrodes provides obtaining almost completely oxidized products that is found to depend on the electronegativity of the initial metals. When applying aluminum electrodes, the process not only provides a high productivity of obtaining dispersed materials (up to 15 g per cycle), but also allows the CO2 conversion rate of up to 14.5%. Moreover, the electroerosion plasma demonstrates the energy efficiency of CO2 decomposition exceeding other plasma-based methods due to ongoing exothermic reactions of metal oxide formation. The as-synthesized products can be used to obtain bulk ceramic materials that is shown by the example of aluminum oxide powders. The hardness of the obtained ceramic specimens produced by SPS method is found to be ∼22 GPa and correlates with the best samples for aluminum oxides.

The Investigation of Triple-Lithiated Transition Metal Oxides Synthesized from the Spent LiCoO2

The environmentally friendly closed cycle of the regeneration process of spent LiCoO2 was successfully developed and the following synthesis of triple-lithiated transition metal oxides was carried out. A hydrometallurgy recycling route with the usage of 1.5 mol/L of malic acid and 3 vol.% of H2O2 as a leaching solution for cobalt extraction was chosen. The efficiency of the cobalt extraction reached 95%. The obtained material was investigated using an X-ray diffraction analysis and the EDX and SEM methods. The electrochemical behavior of the synthesized NCM111 was analyzed and compared to the commercially available material of the same type. The material demonstrated a specific discharge capacity on the first cycle of 163.7 mAh/g. The cyclic resource of the material turned out to be unsatisfactory. In addition, perspective cathode materials, such as NCM622 and NCM811, were obtained. The synthesized materials were analyzed using XRD, SEM, EDX, charge–discharge and cycle life tests, and the CVA and EIS methods. The initial specific discharge capacities of the NCM622 and NCM811 were 168 and 187 mAh/g, respectively. On the fifth cycle, the NCM622 demonstrated an increasing capacity—to 179 mAh/g, unlike NCM811, as the capacity of this material decreased to 141 mAh/g.

Eco-friendly synthesis of anti-microbial and anti-fungal binary metal oxide decorated reduced graphene oxide nanocomposites with complimenting density functional studies

Recently, graphene-based nanocomposites are increasingly becoming popular for a variety of biological applications, due to their extraordinary physicochemical properties. Herein, we present an eco-friendly method for the preparation of a novel nanocomposite based on reduced graphene oxide (rGO) decorated with tin oxide (SnO2) and zinc oxide (ZnO) nanoparticles. The rGO and binary metal oxides-based nanocomposite (rGO/ZnO/SnO2) with enhanced biocompatibility was prepared by using Mentha longifolia extract as a non-hazardous reducing agent. The rich polyphenolic and flavonoids contents of Mentha longifolia have functioned as potential bio-reductants, which are not only suitable for the synthesis of rGO/ZnO/SnO2, but also effectively stabilized the resulting composite. Initially, to determine the reducing ability of Mentha longifolia, the redox potential and chemical composition of green extract was investigated by cyclic voltammetry (CV) and liquid chromatography-mass spectrometry (LC-MS), respectively. On the other hand, the structural composition and morphology of the resultant composite was confirmed by X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared spectroscopy (FT-IR) and UV–visible spectroscopy (UV), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDS). Furthermore, the biological potential of rGO/ZnO/SnO2 is determined by evaluating the antimicrobial and antifungal properties of the resulting composite against various pathogens such as, Staphylococcus aureus (SA), Candida albicans (CA) and Clostridium dificile (CD). Notably, the composite has demonstrated superior antibacterial and antifungal properties when compared to its individual counterparts including rGO, SnO2 and ZnO. Density functional calculations complement the experimental findings, as the periodic boundary conditions reveal high binding energy of −14.8 keV for the rGO/ZnO/SnO2 nanocomposite.

Improvement of the CO2 Sensitivity: HPTS-Based Sensors along with Zn@SnO2 and Sn@ZnO Additives.

Fluorescent pH-sensitive indicator dye, 8-hydroxypyrene-1,3,6-trisulfonic acid (HPTS), has become known as a preferred alternative for continuous and accurate monitoring of dissolved and/or gaseous CO2 in chemistry, medical, and biochemical research. The objective of this work is to enhance the HPTS dye's CO2 sensitivity in the presence of Zn@SnO2 and Sn@ZnO additive particles. Sol-gel synthesized metal oxide semiconductors (MOSs) were characterized using XRD, XPS, and SEM. The fluorophore dye and the MOS additives were embedded in the ethyl cellulose (EC) polymeric matrix to prepare the sensing thin films. The steady-state and decay kinetic measurements of the HPTS-based composites were obtained by PL spectroscopy for the concentration ranges of 0-100% p[CO2]. As expected, the addition of MOSs improves the sensor characteristics, specifically its CO2 sensing ability, linear response range, and relative signal change compared to the free form of HPTS. The CO2 sensitivities of the HPTS-based thin films were found at 17.6, 23.2, and 40.9 for the undoped, Zn@SnO2,-doped, and Sn@ZnO-doped forms of the HPTS, respectively. Additionally, the response and recovery times of the HPTS-based sensor agent with Sn@ZnO were measured as 10 and 460 s, respectively. The obtained results demonstrate that materials composed of HPTS with MOSs are potential candidates for CO2 sensors.

Improvement of the photocatalytic activity of CeO2 on the degradation of chlorophenolic compounds obtained by solution combustion synthesis (SCS). Effect of urea as fuel

This work presents a detailed study to determine the optimal urea content in the synthesis of CeO2 by the solution combustion method and thus obtain the highest photocatalytic activity in the degradation of phenolic compounds. Four CeO2 with different molar ratios urea:Ce(IV) = 0:1, 2:1, 4:1, and 7:1 were synthesized. The synthesized oxides were evaluated in the photocatalytic degradation of 3-chlorophenol, 4-chlorophenol, and 2,4-dichlorophenol using UV light. The synthesized materials were characterized by XRD, Raman spectroscopy, UV–Vis diffuse reflectance spectroscopy, FTIR spectroscopy, N2 physisorption, scanning electron microscopy, transmission electron microscopy and photoluminescence spectroscopy. Raman characterization showed that using urea as fuel favors the formation of oxygen vacancies, increasing up to the urea:Ce(IV) = 4:1 ratio. Photoluminescence studies indicated a decrease on the recombination of photogenerated charges when the oxides are synthesized with urea. The CeO2 synthesized without urea showed 26.6% degradation of 3-chlorophenol, which increased up to 73.6% when it was synthesized with urea. The photocatalytic activity improved mainly due to a higher content of oxygen vacancies and lower recombination of the photogenerated charges. The synthesis method used led to the formation of CeO2 with improved physicochemical properties, so its implementation in the synthesis of other metal oxides and the use of other fuel agents is of great interest for its investigation.

Phytochemicals assisted green synthesis of copper oxide/cobalt oxide as efficient electrocatalyst for oxygen evolution reaction

Electrocatalytic water splitting is a promising solution to resolve the global energy crisis. Tuning the morphology and elemental composition is a crucial aspect in designing highly-efficient nanomaterials based electrocatalyst for water splitting. Herein, green synthesis using phytochemicals from aloe vera leaves extract was employed to hydrothermally synthesize copper oxide/cobalt oxide nanostructures on nickel foam. The reaction medium was performed in presence of mineralizers of different pH; hydrochloric acid (HCl), citric acid (CA), urea, diethyl amine (DEA) and sodium hydroxide (NaOH) to produce five different compositions of copper oxide/cobalt oxide on nickel foam. Based on FESEM and EDS analysis, it was verified that the plant mediated hydrothermal process yielded interesting morphologies and the elemental composition of the synthesized metal oxide nanostructures distinctly varied with effect to the different mineralizers used. Use of acidic mineralizers such as hydrochloric acid and citric acid favoured formation of copper oxide whereas basic mineralizers such as urea, diethyl amine and sodium hydroxide favoured formation of cobalt oxide. The green synthesis of metal oxide electrode in presence of urea exhibits the best OER electrocatalytic performance with an overpotential of 390 mV, and 453 mV for a current density of 50 mA cm−2 and 100 mA cm−2 respectively. The sample also exhibited sustained stability over 70 h, hence proving that the proposed electrode can serve as an efficient catalyst for electrocatalytic OER.

Synthesis and characterization of MgZnCo ternary mixed metal oxide by the sonochemical method for solid hydrogen storage

In the present investigation, MgZnCo ternary nanocomposites were developed via a one-step sonochemical technique. The nanocomposite was characterized using structural and optical methods. The formation of different crystalline nanocomposite phases (MgO, ZnO, and Co3O4), and a binary phase (Mg-Zn) has been confirmed by X-ray diffraction. Also, it was indicated that varying of Co molar ratio had an impact on the average sizes of the nanoparticles. SEM showed octahedron-shaped nanoparticle morphology with different average sizes for the nanocomposites prepared. Photoluminescence analysis showed the presence of green and ultraviolet emissions, with green luminescence bands being most often observed. with the intention of discovering samples with suitable structural and optical properties for future solid hydrogen storage applications.

Zinc oxide nanostructures: review of eco-friendly synthesis and technological applications

The global community faces significant challenges with regard to energy and the environment. Scientists and engineers have developed innovative techniques in nanotechnology and materials science, particularly in eco-friendly synthesis of metal oxides, to address these challenges. This review discusses current trends in eco-friendly synthesis and technological applications of zinc oxide (ZnO) nanostructures beyond the biomedical field mostly presented in the literature. Green methods of zinc oxide synthesis have attracted researchers due to their low toxicity, versatility and environmentally friendly nature. Zinc oxide nanoparticles (NPs) possess unique optical and thermal characteristics, a wide band gap, high excitation binding energy and are generally recognized as safe and effective, contributing to their broad range of applications. Conventional synthesis methods have been reported to have potential toxicity effects, while green synthesis offers recognized advantages. This review also explores the mechanism of zinc oxide NP formation. Moreover, this review provides an overview of diverse applications of zinc oxide NPs, including energy devices (solar cells), cement concrete, sensors, water and environmental remediation, enhanced oil recovery, coolants and biomedicine. Further studies are recommended to explore additional properties and applications of zinc oxide NPs using the latest environmentally friendly approaches.

Synthesis of carbon nanotube-iron oxide composites via combustion waves for hybrid Li-ion battery anodes

The design and synthesis of suitable transition metal oxide (TMO) with carbonaceous material are crucial to produce high-performance anodes for Lithium-ion batteries (LIBs). Here, we show a facile synthesis method for iron oxide and carbon nanotube (CNT) composite via CNT-guided combustion waves. The combustion waves propagate through a freestanding film composed of multi-walled CNTs (MWCNTs), iron nitrate, and combustible nitrocellulose, synthesizing the composite in one-pot within a few seconds. The resulting composite consists of MWCNT networks encapsulating iron oxide submicron particles (CFs). The composite electrode employing optimized CFs provides exceptional initial specific capacity and rate capability (792 mAh/g at 0.1C and 588 mAh/g at 5C) and an increased capacity of 1215 mAh/g after 500 charge–discharge cycles at 1C. The morphological and electrochemical characterization reveal pulverized nanoparticles encapsulated within MWCNT networks, entailing hybrid capacities of redox conversion and pseudocapacitance. This facile synthesis method for TMO–MWCNT composites provides a feasible family of low-cost composite electrodes for high-performance LIBs.

A review on ultrasound assisted synthesis of metal oxide and doped metal oxide nanocatalysts and subsequent application as photocatalyst for dye degradation

AbstractIn recent years, research on improving the synthesis of catalysts has been at the forefront because of advancements in nanotechnology and greener conventions. Using ultrasound (US) during nanocatalysts synthesis is one of the green approaches that can yield improved catalyst characteristics under conditions of shorter reaction time and requirement of low temperature and pressure. The current paper aims at giving an insight into US‐assisted synthesis (emphasized on sol‐gel and hydrothermal) of different metal oxide nanocatalysts. It has been elucidated that US‐assisted synthesis gives nanocatalyst with narrower particle size distribution with lower mean size, higher surface area, better morphology with less agglomeration, and higher catalytic activity. Ultrasound has thus been demonstrated to yield improvements in morphological, optical, and electronic properties of the nanocatalysts, however, scalability and industrial application of sonochemical synthesis have not been seen very popular. Some guidelines for future research into the development of novel nanocatalysts and industrial scale‐up studies are also provided. The review also summarizes the application of these metal oxides as photocatalysts for dye degradation or effluent treatment containing dyes, highlighting the fundamentals of photocatalysis as well. A comparative study has been reported for catalysts obtained using the US‐assisted synthesis and conventional synthesis of the photocatalysts in terms of catalytic activity. The benefits of using ultrasound‐assisted synthesis in terms of higher photocatalytic degradation have been clearly demonstrated.

Lattice Oxygen Regulation of Perovskites for Chemical Looping Oxidative Dehydrogenation of Ethylbenzene to Styrene

The direct dehydrogenation process produces over 90% of global styrene. However, it is hampered by high energy consumption due to equilibrium limitation, a high steam/ethylbenzene feeding ratio, and complicated separation procedures. In this study, we propose the synthesis of a novel perovskite-structured metal oxide as the redox catalyst for chemical looping oxidative dehydrogenation (CL-ODH) of ethylbenzene into styrene. Lower ethylbenzene activation temperature and higher oxygen storage capacity contributing to high ethylbenzene conversion are achieved by Mn doping of the B site in SrFeO3−δ, and styrene yield is further enhanced by Ba doping of the A site. The optimized Sr0.8Ba0.2Fe0.2Mn0.8O3−δ catalyst exhibits favorable dehydrogenation activity but is deactivated in the first five redox cycles due to the severe carbonation and perovskite structure decomposition. The decarbonization treatment on the catalyst at 950 °C in an O2 atmosphere restores the perovskite structure and dehydrogenation activity, resulting in 85% ethylbenzene conversion and 89% styrene selectivity at 550 °C. Ethylbenzene on the catalyst undergoes full combustion via adsorbed oxygen, ODH of ethylbenzene into styrene and H2O using lattice oxygen, and direct dehydrogenation without available lattice oxygen. The proposed redox catalyst demonstrates efficient conversion of ethylbenzene into styrene, showing great potential for the energy conservation and process intensification of styrene production.

强耦合氧化钼氮碳复合材料的制备及其锂离子存储性能研究

Molybdenum oxide (MoO3) is an attractive anode material for lithium-ion batteries (LIBs); however, its low electrical conductivity, large volume expansion after lithiation, and slow Li-ion diffusion kinetics severely limit its practical applications. Here, ultrafine MoO3 nanoparticles (NPs) (10–15 nm) are synthesized from heavily Mo/N-doped carbonaceous precursors, resulting in MoO3 NPs confined in an N-doped carbon network. This design allows fast electron conduction and short Li-ion diffusion paths; meanwhile, abundant N species and O vacancies on the MoO3 surface lower the Li-ion adsorption barrier and together contribute to the durable Li-ion storage at high current rates. Notably, the obtained nanocomposite NC-MoO3 exhibits a high capacity of 1362 mA h g−1 (0.1 A g−1) and maintains a reversible capacity of 394 mA h g−1 at 10.0 A g−1. A coin-type full LiFePO4//NC-MoO3-400 cell obtains a large specific capacity of 81 mA h g−1 at 5 C. Our work inspires the design and confinement synthesis of other transition metal oxides embedded in conducting carbon networks for practical LIB applications.

Physical properties and pharmacological applications of Co3O4, CuO, NiO and ZnO nanoparticles.

Nano materials have found developing interest in biogenic approaches in the present times. In this study, metal oxide nanoparticles (NPs) such as cobalt oxide (Co3O4), copper oxide (CuO), nickel oxide (NiO) and zinc oxide (ZnO), were synthesized using a convenient and rapid method. The structural features of synthesized metal oxide NPs were studied using various microscopic and spectroscopic techniques like SEM, TEM, XRD, FTIR and EDX. The characterization results confirmed that the prepared NPs possess highly pure, unique and crystalline geometry with size ranging between 10 and 20nm. The synthesized nanoparticles were successfully employed for pharmacological applications. Enzyme inhibition potential of NPs was evaluated against the urease and tyrosinase enzymes. The percent inhibition for the urease enzyme was observed as 80 to 90% by using Co3O4, CuO, NiO and ZnO NPs while ZnO NPs were found to have best anti-urease and anti-tyrosinase activities. Moreover, effective inhibition was observed in the case of ZnO NPs at IC50 values of 0.0833 and 0.1732 for urease and tyrosinase enzymes which were comparable to reference drugs thiourea and kojic acid. The lower the IC50 value, higher the free radical scavenging power. Antioxidant activity by DPPH free radical scavenging method was found moderately high for the synthesized metal oxide NPs while best results were obtained for Co3O4 and ZnO NPs as compared to the standard ascorbic acid. Antimicrobial potential was also evaluated via the disc diffusion and well diffusion methods. CuO NPs show a better zone of inhibition at 20 and 27mm by using both methods. This study proves that the novel metal oxide NPs can compete with the standard materials used in the pharmacological studies nowadays.