Layered Potassium Titanium Niobate/Reduced Graphene Oxide Nanocomposite as a Potassium‑Ion Battery Anode

With graphite currently leading as the most viable anode for potassium-ion batteries(KIBs),other materials have been left relatively underexamined.Transition metal oxides are among these,with many positive attributes such as synthetic maturity,longterm cycling stability and fast redox kinetics.Therefore,to address this research deficiency we report herein a layered potassium titanium niobate KTiNbO5(KTNO)and its rGO nanocomposite(KTNO/rGO)synthesised via solvothermal methods as a high-performance anode for KIBs.Through effective distribution across the electrically conductive rGO,the electrochemical performance of the KTNO nanoparticles was enhanced.The potassium storage performance of the KTNO/rGO was demonstrated by its first charge capacity of 128.1 mAh g^(−1) and reversible capacity of 97.5 mAh g^(−1) after 500 cycles at 20 mA g^(−1),retaining 76.1%of the initial capacity,with an exceptional rate performance of 54.2 mAh g^(−1)at 1 A g^(−1).Furthermore,to investigate the attributes of KTNO in-situ XRD was performed,indicating a low-strain material.Ex-situ X-ray photoelectron spectra further investigated the mechanism of charge storage,with the titanium showing greater redox reversibility than the niobium.This work suggests this lowstrain nature is a highly advantageous property and well worth regarding KTNO as a promising anode for future high-performance KIBs.

Advanced Nanocomposite Arabic Gum Polyacrylic Acid Hydrogels for Flexible Supercapacitors

In this work,the fabrication and characterization of the nanocomposite hydrogel,as a solid electrode in electro-chemical cell and gel electrolyte material using Indium titanium oxide/polyethylene terephthalate(ITO/PET)flex-ible substrate for double-layer supercapacitors have been reported.The nanocomposite hydrogel composed of Arabic gum(AG),Acrylic acid(AA),reduced graphene oxide(RGO),and silver nanoparticles(AgNPs)was fab-ricated via a physical cross-linked polymerization reaction,in which the ascorbic acid was used as a reducing agent to generate AgNPs and to convert Graphene oxide(GO)to RGO during the polymerization reaction.The morphology and structural characteristics of nanocomposite hydrogel were investigated using atomic force microscopy(AFM),scanning electron microscope(SEM),Fourier transfer infrared(FTIR),and X-rayfluores-cence(XRF).Additionally,the effect of RGO and AgNPs on hydrogel stability was assessed through Thermogra-vimetric analysis(TGA)and differential scanning calorimetry(DSC),while its mechanical properties were studied using the nanoindentation test.Electrochemical impedance spectroscopy(EIS),and cyclic voltammetry(CV)were also conducted to study the electrochemical properties of the prepared hydrogel.The effects of AgNPs,RGO,and water content were all considered in the study of supercapacitor performance.The microstructural tests showed that the nanocomposite hydrogel has a relatively high swelling rate,which has a crucial effect on the capa-citance.Furthermore,the effects of increasing AgNP concentration and water content in the hydrogel matrix showed a significant improvement in its electrochemical performance,compared with that for Arabic gum poly acrylic acid(AGPAA)hydrogel itself,were the specific capacitance exhibited a significant enhancement,convert-ing from a low value to a substantially higher capacitance value.Moreover,when the nanocomposite hydrogel was used as the working electrode in an electrochemical cell with a hydrochloric acid(HCl)electrolyte solution,it exhibited good electrode performance.Additionally,using(ITO/PET)as aflexible substrate for nanocomposite hydrogel shows an improvement in their suitability for supercapacitor applications.Therefore,it is suggested that the fabricated hydrogel supercapacitor has potential applications in thefield of renewable and clean energy harvesting.

Synthesis, properties, and applications of graphene oxide/reduced graphene oxide and their nanocomposites

Thanks to their remarkable mechanical, electrical, thermal, and barrier properties, graphene-based nanocomposites have been a hot area of research in the past decade. Because of their simple top-down synthesis, graphene oxide (GO) and reduced graphene oxide (rGO) have opened new possibilities for gas barrier, membrane separation, and stimuli-response characteristics in nanocomposites. Herein, we review the synthesis techniques most commonly used to produce these graphene derivatives, discuss how synthesis affects their key material properties, and highlight some examples of nanocomposites with unique and impressive properties. We specifically highlight their performances in separation applications, stimuli-responsive materials, anti-corrosion coatings, and energy storage. Finally, we discuss the outlook and remaining challenges in the field of practical industrial-scale production and use of graphene-derivative-based polymer nanocomposites.

Surface Oxidation of Al_2O_3/SiC Nanocomposite: Phase Transformation and Microstructure

The surface oxidation behavior of pressureless sintered Al2O3/SiC nanocomposite was studied from 1000 to 1400 ℃ for more than 10 h in air. Weight gain during the process of heat treatment was measured by TG analysis. Phase transformation and microstructure changes of these specimens due to oxidation were investigated with X-ray diffraction （XRD）, SEM and EDX technology. Thermogravimetric analysis show that the weight gain as a result of oxidation of SiC become significant above 1200 ℃. In the range of 1000 - 1300 ℃, the SiC grits are usually coated with a layer of amorphous silica after oxidation. Above 1300 ℃, the amorphous silica reacted with alumina matrix and formed mullite or crystallized into cristobalite. The rate of oxidation depends on the formation of dense cristobalite film. Large amount of needle-like mullite and alumina crystals are formed on the surface after oxidation at 1400℃.

Polyimide-silver nanocomposite containing phosphine oxide moieties in the main chain:Synthesis and properties

New flame-retardant polyimide-silver nanocomposite containing phosphine oxide moiety in the main chain was synthesized by a convenient ultraviolet irradiation technique.A precursor such as AgNO_3 was used as the source of the silver particles.Polyimide 6 as a source of polymer was synthesized by polycondensation reaction of bis（3-aminophenyl） phenyl phosphine oxide 4 with pyromellitic anhydride 5 in the presence of iso-quinoline as base and in m-cresol solution.The resulting composite film was characterized by FTIR spectroscopy,X-ray diffraction（XRD）,transmission electron microscopy（TEM）,thermogravimetry（TGA） and differential scanning calorimetry（DSC）.The average size of the nanometer Ag particles is about 10 nm.The temperature of 5 and 10%weight loss and also the char yield at 600℃of polyimide-silver nanocomposite 6a were higher than the pure PI 6.

Magnetic Fe_3O_4-Reduced Graphene Oxide Nanocomposites-Based Electrochemical Biosensing

An electrochemical biosensing platform was developed based on glucose oxidase(GOx)/Fe3O4-reduced graphene oxide(Fe3O4-RGO) nanosheets loaded on the magnetic glassy carbon electrode(MGCE).With the advantages of the magnetism, conductivity and biocompatibility of the Fe3O4-RGO nanosheets, the nanocomposites could be facilely adhered to the electrode surface by magnetically controllable assembling and beneficial to achieve the direct redox reactions and electrocatalytic behaviors of GOx immobilized into the nanocomposites. The biosensor exhibited good electrocatalytic activity, high sensitivity and stability. The current response is linear over glucose concentration ranging from 0.05 to 1.5 m M with a low detection limit of0.15 μM. Meanwhile, validation of the applicability of the biosensor was carried out by determining glucose in serum samples. The proposed protocol is simple, inexpensive and convenient, which shows great potential in biosensing application.

Highly dispersed NiMo@rGO nanocomposite catalysts fabricated by a two-step hydrothermal method for hydrogen evolution

Exploring and designing a high-performance non-noble metal catalyst for hydrogen evolution reaction(HER)are crucial for the large-scale application of H2 by water electrolysis.Here,novel catalysts with NiMo nanoparticles decorated on reduced graphene oxide(NiMo@r GO)synthesized by a two-step hydrothermal method were reported.Physical characterization results showed that the prepared NiMo@r GO-1 had an irregular lamellar structure,and the NiMo nanoparticles were uniformly dispersed on the rGO.NiMo@rGO-1 exhibited outstanding HER performance in an alkaline environment and required only 93 and 180 mV overpotential for HER in 1.0 M KOH solution to obtain current densities of-10 and-50 mA·cm^(-2),respectively.Stability tests showed that NiMo@rGO-1 had a certain operating stability for32 h.Under the same condition,the performance of NiMo@rGO-1 can be comparable with that of commercial Pt/C catalysts at high current density.The synergistic effect between NiMo particles and lamellate graphene can remarkably promote charge transfer in electrocatalytic reactions.As a result,NiMo@rGO-1 presented the advantages of high intrinsic activity,large specific surface area,and small electrical impedance.The lamellar graphene played a role in dispersion to prevent the aggregation of nanoparticles.The prepared NiMo@rGO-1 can be used in anion exchange membrane water electrolysis to produce hydrogen.This study provides a simple preparation method for efficient and low-cost water electrolysis to produce hydrogen in the future.

Effect of graphene oxide on the corrosion,mechanical and biological properties of Mg-based nanocomposite

This study investigates the effect of graphene oxide(GO)on the mechanical and corrosion behavior,antibacterial performance,and cell response of Mg–Zn–Mn(MZM)nanocomposite.MZM/GO nanocomposites with different amounts of GO(i.e.,0.5 wt%,1.0 wt%,and1.5 wt%)were fabricated by the semi-powder metallurgy method.The influence of GO on the MZM nanocomposite was analyzed through the hardness,compressive,corrosion,antibacterial,and cytotoxicity tests.The experimental results showed that,with the increase in the amount of GO(0.5 wt%and 1.5 wt%),the hardness value,compressive strength,and antibacterial performance of the MZM nanocomposite increased,whereas the cell viability and osteogenesis level decreased after the addition of 1.5 wt%GO.Moreover,the electrochemical examination results showed that the corrosion behavior of the MZM alloy was significantly enhanced after encapsulation in 0.5 wt%GO.In summary,MZM nanocomposites reinforced with GO can be used for implant applications because of their antibacterial performance and mechanical property.

Pt-Containing Ag_2S-Noble Metal Nanocomposites as Highly Active Electrocatalysts for the Oxidation of Formic Acid

Nanocomposites with synergistic effect are of great interest for their enhanced properties in a given application. Herein, we reported the high catalytic activity of Pt-containing Ag2S-noble metal nanocomposites in formic acid oxidation, which is a key reaction in direct formic acid fuel cell. The electrochemical measurements including voltammograms and chronoamperograms are used to characterize the catalytic property of Pt-containing nanocomposites for the oxidation of formic acid. In view of the limited literatures on using nanocomposites consisting of semiconductor and noble metals for catalyzing the reactions of polymer electrolyte membrane-based fuel cells, this study provides a helpful exploration for expanding the application of semiconductor-noble metal nanocomposites.

Buckling analysis of embedded graphene oxide powder-reinforced nanocomposite shells

In this study,the buckling analysis of a Graphene oxide powder reinforced(GOPR)nanocomposite shell is investigated.The effective material properties of the nanocomposite are estimated through Halpin-Tsai micromechanical scheme.Three distribution types of GOPs are considered,namely uniform,X and O.Also,a first-order shear deformation shell theory is incorporated with the principle of virtual work to derive the governing differential equations of the problem.The governing equations are solved via Galerkin’s method,which is a powerful analytical method for static and dynamic problems.Comparison study is performed to verify the present formulation with those of previous data.New results for the buckling load of GOPR nanocomposite shells are presented regarding for different values of circumferential wave number.Besides,the influences of weight fraction of nanofillers,length and radius to thickness ratios and elastic foundation on the critical buckling loads of GOP-reinforced nanocomposite shells are explored.

Formation mechanism of Al2O3/MoS2 nanocomposite coating by plasma electrolytic oxidation(PEO)

In this study,an Al2O3/MoS2 nanocomposite coating was created on an aluminum 1050 substrate using the plasma electrolytic oxidation method.The zeta potential measurements showed that small MoS2 particles have negative potential and move toward the anode electrode.The nanoparticles of MoS2 were found to have a zeta potential of-25 mV,which prevents suspension in the solution.Thus,to produce an Al2O3/MoS2 nanocomposite,one has to use the microparticles of MoS2.The X-ray diffraction analyses showed that the produced coatings containedα-Al2O3,γ-Al2O3,and MoS2,and that the size of MoS2 particles can be reduced to 30 nm.It was observed that prolonged suspension in the electrolyte results in an enhanced formation of an Al2O3/MoS2 nanocomposite.Using the results,it was hypothesized that the mechanism of the formation of the Al2O3/MoS2 nanocomposite coating on the aluminum 1050 substrate is based on electrical energy discharge.

Phase composition,conductivity,and sensor properties of cerium-doped indium oxide

The hydrothermal synthesis of In_(2)O_(3)and CeO_(2)–In_(2)O_(3)is investigated as well as the properties of sensor layers based on these compounds.During the synthesis of In_(2)O_(3),intermediate products In(OH)_(3)and InOOH are formed,which are the precursors of stable cubic(c-In_(2)O_(3))and metastable rhombohedral(rh-In_(2)O_(3))phases,respectively.A transition from c-In_(2)O_(3)to rh-In_(2)O_(3)is observed with the addition of CeO_(2).The introduction of cerium into rh-In_(2)O_(3)results in a decrease in the sensor response to hydrogen,while it increases in composites based on c-In_(2)O_(3).The data on the sensor activity of the composites correlate with XPS results in which CeO_(2)causes a decrease in the concentrations of chemisorbed oxygen and oxygen vacancies in rh-In_(2)O_(3).The reverse situation is observed in composites based on c-In_(2)O_(3).Compared to In_(2)O_(3)and CeO_(2)–In_(2)O_(3)obtained by other methods,the synthesized composites demonstrate maximum response to H_(2)at low temperatures by 70–100℃,and have short response time(0.2–0.5 s),short recovery time(6–7 s),and long-term stability.A model is proposed for the dependence of sensitivity on the direction of electron transfer between In_(2)O_(3)and CeO_(2).

Microwave-assisted catalytic oxidative desulfurization of gasoil fuel using synthesized CuO-ZnO nanocomposites

Recently, organosulfur removal from liquid petroleum fuels is very significant aspect of environment protecting and fuel cell requests. Therefore, improved approaches to remove sulfur are still essential. In the present work, a simple catalytic oxidative desulfurization (CODS) system for Iraqi gasoil fraction has been successfully developed using CuO-ZnO nanocomposites as catalysts, and H 2O 2 as oxidant under microwave irradiation. The main reaction parameters influencing sulfur conversion including microwave power, irradiation time, catalyst dosage and H 2O 2 to gasoil volume ratio have been investigated. The CuO-ZnO nanocomposites was synthesized with different weight ratios and characterized by XRD, FE-SEM, AFM and BET surface area methods. The results reveal that, high sulfur conversion (93%) has been achieved under suitable conditions of microwave CODS as follows: microwave power of 540 W, irradiation time of 15 min, catalyst dosage of 8 g/L (0.4 g), and H 2O 2 ∶gasoil volume ratio of 0.3. The catalyst reusability shows that the synthesized catalyst can be reused five times without an important loss in its activity.

Hydrophobic and Magnetic Reduced Graphene Oxide Nanocomposite for Emulsified Oil Removal

Magnetic reduced graphene oxide(MRGO) nanocomposite was prepared by the chemical coprecipitation method and applied as adsorbent for removing emulsified oil from oily wastewater. SEM, TEM, XRD, FT-IR, VSM and other analytical methods were utilized to characterize the prepared MRGO. The adsorption performance of MRGO was evaluated under different initial adsorbate concentration, MRGO dosage, temperature, and pH value of the solution. The adsorption kinetics and isotherms were investigated. In addition, the MRGO repeatability was also tested. It was found that almost 65%of emulsified oil were removed by MRGO in the first 15 min. The MRGO adsorption capacity and efficiency for removal of adsorbate reached 335.85 mg/g and 92.52% within 60 min, respectively. The adsorption capacity reduced with an increasing MRGO dosage, while increased with the increase of emulsified oil concentration. The adsorption performance of MRGO in the alkaline environment was lower than that in the acidic environment. The adsorption data could well fit to the pseudosecondorder model. The Langmuir model could well describe the isotherm data. The MRGO adsorption capacity was still more than 236.1 mg/g at the sixth regeneration cycle.

Zinc oxide nanocomposites with antitumor activity

Zinc oxide nanocomposites in the form of coatings and composite films with antitumor activity were obtained by deposition of ZnO nanofilms on surfaces of ethyl ether Sali- cylidene DL-tyrosine (S1) and ethyl ether Sali- cylidene DL-tyrosine Cu (II) chelate (S2) by magnetron sputtering of Zn target. Ethyl ether salicylidene DL-tyrosine, Cu (II) chelate of ethyl ether salicylidene DL-tyrosine reveal some anticancer properties. Their zinc oxide nano- composites were obtained in the form of coat- ings (S1 + ZnO, S2 + ZnO) and composite films presenting a mixture of polyvinyl alcohol (PVA) with S1, S2 (S1 + PVA + ZnO, S2 + PVA + ZnO), for the purpose of increasing anticancer activity. Considerable increase in antitumor activity re- veal ZnO nanocomposites with salicylidene amino acid chelates (as distinct from their ethers) in the form of S2 + ZnO (47%) and S2 + PVA + ZnO (48%) in comparison with S2 (20%). Structural, spectral properties of the salicylidene amino acids and their ZnO nanocomposites were studied.

Malus domestica and Solanum lycopersicum Mixtures for the Synthesis of Graphene Silver and Zinc Oxide Nanocomposites

This study reports on the novel and simple green method involving the use of apple (Malus domestica) and tomato (Solanum lycopersicum) extracts in the synthesis of electroactive layers of silver nanoparticles|graphene oxide (AgNPs|GO) and zinc oxide nanoparticles|graphene oxide (ZnONPs|GO). The surface morphology of the green synthesized nanocomposites was studied using High-Resolution Transmission Electron Microscopy (HRTEM), High-Resolution Scanning Electron Microscopy (HRSEM) while the elemental analysis was studied using Fourier Transform Infrared Spectroscopy (FTIR), Raman spectroscopy and X-Ray diffraction (XRD) and their optical properties were further characterised using Ultraviolet Spectroscopy (UV-vis). The electrochemical studies of these nanocomposites were achieved using cyclic voltammetry (CV) where an increase in electron conductivity of the AgNPs|GO and ZnONPs|GO nanocomposite was observed. Comparatively, the silver nanoparticulate-based platforms were observed to have superior electrochemical properties as opposed to the zinc oxide-based platform. The observed electrochemical activities of the synthesized nanocomposites are a good indication of their suitability as electroactive platforms towards the development of electrochemical sensors. Electrochemical sensors are popular in the Electrochemistry field because they may be developed using different methods in order to suit their intended analytes. As such, the synthesis of a variety of electrochemical platforms provides researchers with a vast range of options to select from for the detection of analytes.

Electro-conductive Nanocrystalline Cellulose Film Filled with TiO_2-ReducedGraphene Oxide Nanocomposite

Imparting electro-conductive properties to nanocellulosebased products may render them suitable for applications in electronics,optoelectronics, and energy storage devices. In the present work, an electroconductive nanocrystalline cellulose(NCC) film filled with TiO2-reducedgraphene oxide(TiO2-RGO) was developed. Initially, graphene oxide(GO) was prepared using the modified Hummers method and thereafter photocatalytically reduced using TiO2 as a catalyst. Subsequently, an electro-conductive NCC film was prepared via vacuum filtration with the as-prepared TiO2-RGO nanocomposite as a functional filler. The TiO2-RGO nanocomposite and the NCC/TiO2-RGO film were systematically characterized. The results showed that the obtained TiO2-RGO nanocomposite exhibited reduced oxygen-containing group content and enhanced electroconductivity as compared with those of GO. Moreover, the NCC film filled with TiO2-RGO nanocomposite displayed an electro-conductivity of up to 9.3 S/m and improved mechanical properties compared with that of the control. This work could provide a route for producing electro-conductive NCC films, which may hold significant potential as transparent flexible substrates for future electronic device applications.

Effect of the Addiction of Metal Oxide Nanoparticles on the Physical, Chemical and Thermal Properties of PVA Based Nanocomposites

In this study, poly(vinyl alcohol) (PVA)-based nanocomposites consisting of metallic oxide nanoparticles (TiO2, ZnO, ZrO2) were obtained from an aqueous solution of 7% PVA, in order to compare the microstructural, and physical properties of bionanocomposite films reinforced with various loading contents (0.1%, 0.2% and 0.3% w/w). They were evaluated regarding their molecular toughness through Nuclear Magnetic Resonance (NMR), regarding their chemical structural through Fourier Transform Infrared Spectroscopy (FTIR), regarding their crystallinity throught X-ray Diffraction (XRD), and regarding termal properties through Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC). The NMR results showed that the smallest concentrations of these oxides have a tendency to disperse better in the polymeric matrix, improving the structural toughness. Besides, changes in the termal resistance of the material were found with the use of TGA and DSC.

PVP/Clay/Vanadium Oxide Nanocomposites Development and Characterization for Potential Use as Controlled Drug Release Matrix in Diabetes’ Treatment

Research in drug release field, nowadays, focuses on more efficient systems for better release of the drug and wider timespan of action, granting several benefits to the patient’s organism and to the industry. The present work aims on developing a matrix of polymer nanocomposite based on Polyvinylpyrrolidone (PVP), bentonite clay and two different vanadium oxides, via spray drying technique. The goal is to achieve a long and steady release of metformin hydrochloride in future formulations with this drug. Since either the nanocomposites or metformin hydrochloride is highly hydrophilic, it is most suited for a future formulation of tablets. For now, the nanocomposites obtained were characterized through Nuclear Magnetic Resonance (NMR), Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD), Thermogravimetric Analysis (TGA) and Fourier Transform Infrared Spectroscopy (FTIR). The SEM and XRD analysis portrayed a very amorphous and homogenized material. TGA and FTIR proved the insertion of the nanoparticles, thus granting to the new material a slightly higher thermal resistance. The NMR analysis, using T1H parameters, is key for determining the formulations would behave better for extending the resistance of the nanocomposite’s matrix with the drug in later dissolution of tablets.