Oxide Composites Research Articles

Synthesis of Plasma-Reduced Graphene Oxide/Lithium Titanate Oxide Composite and Its Application as Lithium-Ion Capacitor Anode Material

A plasma-reduced graphene oxide/lithium titanate oxide (PrGO/LTO) composite is prepared as an anode material to enhance the performance of lithium-ion capacitors (LICs). The PrGO/LTO composite is synthesized by mixing graphene oxide (GO) and LTO, followed by a series of freeze-drying and plasma-treatment processes. PrGO forms a porous three-dimensional (3D) structure with a large surface area, effectively preventing the restacking of PrGO while covering LTO. The GO/LTO mixing ratio is controlled to optimize the final structure for LIC applications. In lithium-ion half-cell assembly, the PrGO/LTO-based anode with an 80% mixing ratio exhibits the highest specific capacity of 73.0 mAh g−1 at 20 C. This is attributed to the optimized ratio for achieving high energy density from LTO and high power density from PrGO. In a LIC full-cell comprising PrGO/LTO as the anode and activated carbon as the cathode, the energy and power densities at 1 A g−1 are 40.3 Wh kg−1 and 2000 W kg−1, respectively, with a specific capacitance of 36.3 F g−1 and capacitance retention of 94.1% after 2000 cycles. Its outstanding performance, obtained from incorporating 3D-structured PrGO with LTO at an optimized ratio, lowers the cell resistance and provides efficient lithium-ion diffusion pathways.

Controllable Synthesis of Magnetic Composite Derived from MIL-88D and Study on Adsorption Properties of Cu2+

In this paper, MIL-88D (Fe) with spindle shape was prepared by the hydrothermal synthesis method, a metal oxide with a new structure was obtained by calcination at different temperatures as a precursor, and a magnetic iron oxide composite was prepared successfully. At the same time, it was used as an adsorption material for the adsorption of heavy metal ions Cu2+. The influence of the initial pH value and adsorption time on the adsorption effect was investigated, the adsorption kinetics and adsorption isotherm were further fitted, and the adsorption mechanism was preliminarily analyzed. The results show that the magnetic iron oxide composites have a good adsorption capacity for Cu2+. The pH value is an important parameter that affects the adsorption effect. The adsorption of Cu2+ by magnetic iron oxide composites reached adsorption equilibrium in 30 min. The adsorption of Cu2+ by magnetic iron oxide composites conforms to the second-order reaction kinetics and Langmuir adsorption isotherm equation, which indicates that the adsorption process mainly occurs through chemisorption and typical single-molecular-layer adsorption.

A Review of the Current Research Status of Graphene for the Removal of Microplastics and Antibiotics from Water

As highly representative pollutants among emerging pollutants, antibiotics and microplastics are characterized by strong bioaccumulation, difficult degradation, and high toxicity, and along with the increasing use, the crisis of synergy between the two is increasing. Graphene, a material with high specific surface area and high reactivity, has a wide range of application prospects in the field of water treatment, especially graphene oxide and graphene composites make the application of this material has a certain diversity. The research on graphene and its composites in water membrane treatment and catalytic degradation for the removal of microplastics and antibiotics in recent years is reviewed to explore the research trends and hotspots, and to explore the research prospects.

Influence of Long-Term Freezing of Carcasses in Pre- and Post-Rigor Mortis Stages on the Technological and Nutritional Parameters of the Longissimus lumborum Muscle of Botucatu Rabbits.

The aim was to assess the impact of long-term storage on the quality of Botucatu rabbit meat frozen in pre- and post-rigor stages. The stability of the technological and nutritional parameters of Longissimus lumborum (LL) muscle was analyzed over 12 months. In the post-rigor phase, the dorsal LL surface showed a higher level (p < 0.05) of redness and saturation, while the ventral surface showed a higher level (p < 0.05) of yellowness compared to the pre-rigor LL muscle. During storage, the redness and saturation in the LL muscle decreased (p < 0.05), while the yellowness increased (p < 0.05) on both dorsal and ventral surfaces. In the first six months, the pre-rigor meat had a higher pH (p < 0.05) compared to the post-rigor meat. The fresh meat showed higher (p < 0.05) shear force values in the post-rigor stage. Over the 12-month study period, the lipid oxidation, myofibrillar fragmentation index, gross energy, and levels of protein, fat, and carbohydrates increased (p < 0.05), while the shear force, mineral content, and moisture decreased (p < 0.05). Thus, rigor mortis affects meat color in Botucatu rabbits. Fresh meat in the pre-rigor stage is softer, moister, and less acidic than post-rigor meat after 24 h of chilling. Long-term freezing enhances tenderness, regardless of the rigor phase at freezing, preserving its physical, chemical, and nutritional quality, with minor changes in color, lipid oxidation, and chemical composition.

The influence of graphene oxide on the microstructure and properties of ultrafine-grained copper processed by high-pressure torsion

New metal matrix nanocomposites with enhanced thermal stability were produced in a three step process consisting of mechanical milling, spark plasma sintering and High-Pressure Torsion (HPT). The nanocomposites consisted of a copper matrix and the addition of 1 wt% Graphene Oxide (GO) as a reinforcement. A nanocrystalline microstructure, enhanced hardness and improved thermal stability were achieved. The grain size of the nanocomposites was ∼55 nm which is almost four time smaller than for Cu HPT at 210 nm. Hardnes and ultimate tensile strength of the nanocomposites reach 250 Hv and 700 MPa, respectively, which was more than three times higher than for the initial material. The most important result is that the nanocomposites remained ultrafine-grained up to 500 ⁰C whereas the Cu HPT fully recrystalized after annealing at 300 ⁰C The report also includes an investigation of the electrical conductivity of the copper-based composite which was slightly better than for copper after HPT together with the wear behaviour of this material. This is one of the first reports on copper reinforced with graphene oxide composites produced by HPT and it gives information on its thermal stability, electrical conductivity and wear behaviour together with the microstructural characteristics and mechanical properties.

Lycium ruthenicum stem extract mediated green synthesis of MnO2/Mn3(PO4)2 composite nanowire electrocatalyst for oxygen evolution reaction

A composite of manganese oxide (MnO2) and Mn3(PO4)2 decorated nanowires (MnO2/Mn3(PO4)2) was prepared using Lycium ruthenicum stem-extract mediated green synthesis. This composite material functions as an efficient and long-lasting electrocatalyst for water-splitting reactions, which could significantly improve the performance of oxygen evolution reaction (OER). The OER activity of MnO2/Mn3(PO4)2-based nanowires is boosted by blending with a conducting support, such as manganese oxide (MnO2). The x-ray diffraction pattern and Fourier transform infrared data indicate that the nanowires are highly crystalline. The MnO2/Mn3(PO4)2 composite material demonstrates superior stability compared to its individual constituents and generates a current density of 10 mA cm−2 at a low overpotential of 244 mV for OER in alkaline media. This research may lead to the development of MnO2/Mn3(PO4)2 composite materials as electrocatalysts for overall water-splitting reactions.

Sodium storage performance and mechanism of amorphous FePO4/rGO nanocomposite as a novel anode material for sodium ion batteries

Exploring novel and cost-effective anode materials is highly desired for the development of sodium-ion batteries (SIBs). Herein, an amorphous FePO4/reduced graphene oxide (FP-G) composite is prepared by a simple chemical precipitation method with leaching liquor of jarosite residue as Fe source. When used as a novel anode material for SIBs, this FP-G composite exhibits a high sodium storage activity (341.6 mAh g−1 after 100 cycles at 0.2 A g−1), superior long-term cycling stability (215.8 mAh g−1 after 1500 cycles at 0.5 A g−1), and outstanding high-rate capability (190.8 mAh g−1 at 5.0 A g−1). The FP-G composite shows a significant pseudocapacitance behavior and good electrochemical reversibility during discharge and charge processes. This work proposes a simple, feasible, and cost-effective strategy for the high-valued utilization of jarosite residue, and deeply investigates the sodium storage mechanism and potential value of FP-G composite as a novel anode material for SIBs.

Mechanistically Understanding the Correlation Between Dynamic Interface Variation and Stability of Surface Coating on the NMC811 Materials

AbstractLiNi0.8Co0.1‐Mn0.1O2 (NMC811) is widely used in high energy density lithium‐ion batteries, while dynamic variation of liquid‐solid interface induced by oxygen release/evolution results in unexpected performance decay. Surface coating is an effective strategy in promoting the stability of NMC811 materials, and both coating composition and nanostructure arrangement would substantially impact the dynamic variation of liquid‐solid interfaces. To understand such dynamic variation, here evolution and stability of two selected NMC811 materials coated with oxides (the same oxide composition but different nanostructure arrangements) are compared, i.e., concentration uniform core‐shell NMC811 (CUCS811) and concentration gradient core‐shell NMC811 (CGCS811). The gas evolution from the home‐setup operando gas monitors (at 45 and 65 °C) implies that CUCS811 presents more operation and thermal stability because of less amount of CO2 and CH4 along with prolonged interval time in gas production. Composition variation of interfaces indicates that CUCS811 presents more stable interfacial evolution behaviors since more F‐ and P‐rich species for stabilizing the solid‐electrolyte interfaces are detected. The stability analysis suggests that uniform arrangement of Al2O3 and boride in the coating is prone to prevent the interface from degradation upon dynamic interface variation, which is useful in promoting the performance stability of NMC811 positive electrode materials.

Enhanced ethanol response, selectivity, and stability of ZIF-67-derived ZnO/Co3O4 bimetallic oxide composites

This study aims to develop an efficient, stable, highly humidity-resistant, and selective ethanol sensing material. In this study, ZIF-67-derived ZnO/Co3O4 bimetallic oxide composite materials were synthesized via a co-precipitation method followed by a one-pot hydrothermal reaction. Different mass ratios (10 %, 30 %, 50 %) of ZIF-67-Derived ZnO/Co3O4 composite materials were obtained by varying the mass of Co3O4. The ethanol sensing performance of these composite materials were investigated. Results demonstrated that the ZnO/Co3O4-ZIF30 % sensor exhibited a response value of 42.3 for 50 ppm ethanol at 240 °C, with response and recovery times of 50 s and 200 s, respectively. Furthermore, the ZnO/Co3O4-ZIF30 % sensor showed almost no change in response value as humidity increased from 30 % RH to 80 % RH, indicating remarkably high humidity resistance. Additionally, ZnO/Co3O4-ZIF30 % exhibited high selectivity for ethanol. Consequently, the ZnO/Co3O4-ZIF30 % material demonstrated superior ethanol sensing performance. Finally, the multiple gas sensing mechanisms of ZIF-67-derived ZnO/Co3O4 composites were carefully investigated. In conclusion, the ZnO/Co3O4-ZIF30 % material demonstrated outstanding ethanol sensing performance, indicating its significant potential for practical applications.

Plasma-enhanced atomic layer deposition as a technique for controlling the composition and properties of indium-based transparent conductive oxides

Indium oxide and doped indium oxide films were successfully grown utilizing a plasma-enhanced atomic layer deposition supercycling process, which was found to be an effective means of controlling films’ composition and, hence, their properties. Using trimethylindium and oxygen plasma as an indium precursor and a co-reactant, respectively, a growth rate of approximately 1.26 Å per cycle was obtained based on thickness measurements by spectroscopic ellipsometry. Three distinct dopants, Sn, Ti, and Mo, have been incorporated into indium oxide. The effects of dopant type, cycle ratio of dopant to indium oxide, and thermal annealing on the structural, electrical, and optical properties were studied. The deposited films consisted of polycrystalline columnar grains perpendicular to the substrate with a cubic bixbyite structure and [111] as the favored growth direction. Thermal annealing had a significant effect on the film characteristics, resulting in an order of magnitude reduction in resistivity, as well as changes in transmittance in the near-infrared (NIR) and ultraviolet (UV) regions. The lowest resistivities achieved for Sn-doped, Ti-doped, and Mo-doped were 2.8 × 10−4, 4.2 × 10−4, and 6.1 × 10−4 Ω cm, respectively. The changes are attributed to dopant activation, as the UV shift between the differently doped samples may be linked to the Moss–Burstein effect and the NIR behavior can be explained by an increase in charge carrier density, as predicted by the Drude model. The three dopants primarily provide a trade-off between electrical resistance and NIR transparency. Mo-doped films exhibited the highest near-infrared transparency, while Sn-doped films offered the lowest sheet resistance.

Bimetallic MOF-derived manganese-cobalt composite oxide as high-performance zinc-ion batteries cathode

Bimetallic MOF-derived manganese-cobalt composite oxide as high-performance zinc-ion batteries cathode

Synthesis and Characterization of Polyaniline/CuO Nanocomposites with Various Temperature

Polyaniline (PANI) metal oxide composites are known for their high electrical conductivity, environmental stability, and enhanced mechanical strength, making them valuable in applications such as sensors, batteries, and electromagnetic shielding. This study focuses on synthesizing and characterizing PANI/CuO nanocomposites to examine their structural, morphological, and functional properties at different synthesis temperatures. By integrating the conductive polymer PANI with copper oxide (CuO), a p-type semiconductor with a narrow band gap, the material’s capabilities are significantly enhanced. The oxidative polymerization of aniline, the process by which PANI is formed, requires precise control of oxidizing agents and reaction conditions, as these factors directly affect the polymerization, conductivity, and overall properties of the resulting nanocomposite. The PANI/CuO nanocomposites were synthesized at three different temperatures: 10℃, 25℃, and 50℃, to determine how temperature affects their characteristics. Fourier Transform Infrared (FTIR) spectroscopy and Scanning Electron Microscopy (SEM) were employed to analyze these nanocomposites. FTIR results revealed shifts in the quinoid and benzenoid rings, indicating hydrogen bonding between the NH group of PANI and the CuO surface, which accelerates charge transfer. The SEM analysis showed that while pure PANI exhibits a uniform globular morphology, the PANI/CuO nanocomposites display a nanorod morphology. These morphological differences impact the surface area and electrical conductivity of the composites, highlighting the significance of temperature in tailoring the material's properties for specific applications.

Dropwise condensation performance of sprayable polymer/copper oxide composite coating

Even though dropwise condensation (DWC) has received significant attention for its potential to enhance heat transfer performance at a higher order than filmwise condensation (FWC), the scalability of durable DWC-promoting surfaces to sustain prolonged condensation remains challenging. The spray coating presents itself as a potential scalable method to deposit hydrophobic coating onto a metallic substrate. However, the conventional sprayable fluoropolymer exhibits poor adhesion to the substrate and thus requires a base coat before it can be deposited on a metallic substrate. To address this challenge, this study investigated dropwise condensation performance on a polytetrafluoroethylene/imide-based binder/copper oxide composite (PTFE/PI/CuO) coating that is deposited into a copper substrate using simple one-step spray coating and thermal annealing. The PTFE particles provide the necessary hydrophobic characteristics. At the same time, the polymer binder fills the pores between the particles, preventing droplet nucleation within the structure and minimizing the occurrence of flooding that can lead to undesirable droplet pinning. The PTFE/PI/CuO coating successfully promotes pinned-free dropwise condensation, leading to approximately two times higher heat transfer enhancement than filmwise condensation. Moreover, the formation of micro-scale hydrophilic CuO clusters at the top of the coating surface acts as nucleation sites that increase droplet growth rate and departure frequency without altering the droplet departure radius. As a result, PTFE/PI/CuO exhibits 1.4x times higher heat transfer over the PTFE/PI. Furthermore, a durability enhancement was obtained by adding sub-micron copper particles. While PTFE/PI coating failed after exposure to steam, no visible damage was observed from PTFE/PI/CuO, thus indicating enhanced durability. Moreover, the PTFE/PI/CuO composite also exhibited resistance against mechanical damage as its heat transfer performance remained similar even after being subjected to abrasion. Finally, the pull-off adhesion test revealed that PTFE/PI/CuO has higher adhesion strength than PTFE/PI, making it more suitable for dropwise condensation application.

Biomass modified carbon nanofibers use for flexible supercapacitor electrodes with thermal conductive performances

The advancement of flexible electrode with excellent energy storage is essential for supercapacitors. Herein, a porous biomass-doped carbon nanofiber@bimetallic oxide composite (B-CNF@NiO/Co3O4) has been prepared as a binder-free flexible electrode. The heteroatoms form biomass not only offer pseudocapacitance but also a multitude of active sites for the grow of bimetallic oxides. The well-grown B-CNF@NiO/Co3O4 shows a high specific capacitance (629.5 F g−1) and the asymmetric flexible supercapacitor (ASC) has an energy density of 31.5 Wh kg−1 at a power density of 757.4 W kg−1. The properties of bimetallic oxides and 3D networks facilitate transportation of interlayer ion, providing a straightforward approach to fabricate non-adhesive flexible electrode with dual functionalities of energy storage. In addition, the thermal conductive experiment demonstrated a favorable thermal conductivity (TC) of 1.06 W m−1 K−1.

Enhancing electrochemical performance of graphene oxide/polyaniline composite through plasma-assisted chemical cross-linking and surface modification

The composite of graphene oxide (GO) and polyaniline (PANI) is a promising electrode material for supercapacitors. A high loading of PANI can provide large specific capacitance, but it is a pervasive challenge to reconcile long-term cycling stability and high-rate discharge. Herein, we focus on a GO/PANI composite with low PANI content (∼25 wt%), developing a stable network of GO with an even distribution of PANI. Moreover, significantly enhanced electrochemical performance is achieved by utilizing plasma technology. The specific capacitance increases by 99 % to 433 F g−1 at 1.5 A g−1 after Argon (Ar) plasma treatment. Even at 15 A g−1, a capacitance retention rate of 91 % is obtained. After 15,000 cycles, the capacitance retention rate is 93 %, surpassing most previously reported GO/PANI composite electrodes. The further assembled all-solid-state supercapacitors can deliver a high energy density of 13.6 Wh kg−1 and exceptional cycling stability. According to results of characterization, it is demonstrated that Ar plasma imparts GO/PANI better surface morphology and achieves etching, reduction of GO, and cross-linking of GO and PANI, thereby activating the electrochemical activities of GO and PANI while ensuring stability. In this regard, the synergistic effects of cross-linking, reduction, and etching, and the mechanism are theoretically illustrated by dynamic differential equations. This work presents plasma processing unique charm for designing graphene-based materials via a customized strategy, exploiting an effectual approach to drive the applications of graphene-based materials in energy storage.

Vacancy-strengthened Cu/Co composite oxides for efficient removal of methylene blue via peroxymonosulfate activation: Synergism of multiple Lewis acid sites

The development of suitable catalysts poses a challenge for the peroxymonosulfate (PMS) activation system used in decontamination process. Here we constructed a series of vacancy-strengthened Cu/Co composite oxides (CuCoO) composed of CuCo2O4 and CuO containing multiple Lewis acid sites. The results demonstrate that the as-prepared CuCoO-2 exhibited exceptional activation performance, broad-ranging degradation capacity, remarkable reusability and stability. The optimized CuCoO-2+PMS system achieved complete removal of methylene blue (MB) in 40 min, while maintaining a degradation efficiency of above 86 % even after 5 cycles. A comprehensive survey revealed that hydroxyl radical (·OH), sulfate radical (SO4.-) and singlet oxygen (1O2) collectively contribute to the degradation of MB in the CuCoO-2+PMS system. Especially, 1O2 was the dominant active species. The synergism of various Lewis acid sites (Cu+/2+, Co2+/3+ and VO/N) as unsaturated surface-bound centers played a pivotal role in promoting non-radical-driven activation of PMS. Meanwhile, the generated VO/N facilitated enhanced metallic valence circulation in CuCoO-2, strengthening electron mediation between PMS and MB. Additionally, possible degradation pathways and toxicity evaluations of MB and its intermediates were proposed. In conclusion, this work offers valuable insights into PMS activation by vacancy-strengthened CuCoO and is of great significance for water purification.

Enhanced degradation of crystal violet using PANI-ZnO nanocomposites: Electro-oxidation and photocatalysis studies

This work compares the transformation capabilities of crystal violet (CV), a toxic cationic dye of the triphenylmethane family, by advanced oxidation processes, especially heterogeneous photocatalysis and electrochemical oxidation, on new nanocomposite materials with a composition of zinc oxide (ZnO) and polyaniline (PANI) by chemical polymerization in solution. Concerning the synthesis of PANI, we have exploited the radical oxidative polymerization method; this latter is functional and uncomplex, as it does not require expensive equipment, using ammonium persulfate as an oxidant with a part of monomer (Aniline) to remove pollutants present in the environment. After physicochemical analyses including FTIR, SEM, and electrochemical characterizations by cyclic voltammetry and conductimetry, the results show that the photocatalytic activity of PANI-ZnO 5 % resulted in a better yield (85 %) compared to PANI alone and other composites (PANI-ZnO 10 % and PANI-ZnO 20 %). However, the electro-oxidation discoloration rates on all PANI alone and PANI-ZnO composite electrodes (5 %, 10 %, and 20 %) reached almost 99 %. To deepen our understanding, computational DFT calculations were employed, complementing experimental findings, and together, they contribute to elucidating the intricate mechanisms underlying the enhanced performance of these nanocomposite materials in both photocatalysis and electrochemical oxidation processes.

Interpretation of complex x-ray photoelectron peak shapes. I. Case study of Fe 2p3/2 spectra

Analyzing transition metal XPS peaks is widely used to determine surface composition and chemistry. However, these peaks have a complex structure, which is still the subject of investigation. Fe 2p analysis is a case in point where the multiplet structure and many-electron-effects lead to peak shapes that cannot be analyzed using standard approaches. Examination of the literature reveals that one of the most widely used approaches to data reduction when processing Fe 2p3/2 spectra involves using symmetric two- or three-component peak fitting with each peak effectively acting to capture a single chemical species (chemistry fit) in the complex spectra. Herein, this approach is compared to an envelope fit approach using Biesinger multiplet components of known iron oxides to determine how effective these methods are in reproducing iron oxide composition. Mixed oxide and metal XPS Fe 2p spectra were synthesized using reference spectra collected experimentally. For the first time, the accuracy and differences between the two approaches are reported. It is demonstrated that no meaningful conclusions can be drawn using single symmetric peaks to analyze complex Fe 2p3/2 spectra, implying that a large portion of the literature is flawed. The envelope fit approach, however, is shown to provide useful information regarding oxide ratios in mixed iron oxide materials, though limitations do exist. A methodology for evaluating the quality of XPS analysis of Fe 2p3/2 spectra is proposed for benchmarking new submissions so that reviewers, authors, and editors can assess these submissions.

Rational design of nitrogen and carbon co-decorated mesoporous TiO2 composites for photocatalytic selective oxidation of alcohols

Photocatalytic organic synthesis has attracted much attention in recent years. Herein, a N and C co-decorated mesoporous TiO2 (mp-NCT) photocatalyst was synthesized for selective oxidation of alcohols. Notably, the as-prepared mp-NCT composites possess large specific surface areas and mesoporous structures, which could provide sufficient active sites and improve mass transfer. Furthermore, the co-doping of N and C species could not only extend the light absorption, but also tune the valence band of TiO2. Meanwhile, numerous oxygen vacancies and intra-band could be introduced, which helps to reduce the combination of the photogenerated carriers. As a result, the mp-NCT composites show excellent photocatalytic performance towards selective oxidation of benzyl alcohol and its derivatives to corresponding aldehydes under simulated sunlight irradiation. Mechanism studies revealed that the photogenerated electrons, holes and high dynamic equilibrium concentration of O2•- radicals were responsible for the efficient conversion of alcohols to aldehydes.

Enhancing the thermoelectric performance of Sr0.6La0.4Nb2O6-δ-based ceramics through composite effects

Donor-doped SrNb2O6-based materials are regarded as highly promising candidates for high-temperature thermoelectric applications. The Sr0.6La0.4Nb2O6-δ/x wt% Ti (x = 1, 5, 10, 15) composite ceramics thermoelectric materials were prepared and the mechanism for enhancing their thermoelectric properties was investigated. The experimental results demonstrate that during sintering, nano-additive titanium powder undergoes oxidation to form TiO2. The inclusion of a secondary phase ultimately leads to successful reduction in electrical resistivity within the composite oxides. Due to crystal defects, complex structure and phonon scattering at grain boundaries, the samples consistently exhibit low thermal conductivity values below 3.0 W m−1K−1. Among them, the sample doped with 10 wt% Ti shows the highest PF value (470.0 μW/mK2 at 1073 K), demonstrating a significant increase in power factor of 280 % compared to Sr0.6La0.4Nb2O6 without the Ti composite. Consequently, the Sr0.6La0.4Nb2O6-δ/10 wt% Ti composite material achieved a maximum ZT value of 0.20, representing a fifty-three percent enhancement compared to the undoped sample.