As-synthesized Composite Material Research Articles

BaO-MWCNT composite material-based electrocatalytic amperometric sensor for the detection of environmentally hazardous Diuron

Population growth has prompted industrialization and intensive agricultural methods, which are linked to issues with flora and fauna and result in deteriorated water quality due to contamination by hazardous, persistent pesticides. In this paper, we have concentrated on the herbicide Diuron (DIU) determination as one such priority pollutant. This study was conducted keeping in mind key factors for a proficient electrochemical sensor development for DIU. The working electrode surface area was modified with the as-synthesized BaO-MWCNT composite material to reinforce the efficiency of the Faradaic reaction. A three-fold magnification in DIU anodic peak current was witnessed at the modified electrode in contrast to an unmodified electrode, demonstrating the enhanced electrochemical surface area of the BaO-MWCNT/MCPE. Additionally, the least charge transfer resistance and facile reaction catalysis for strong analyte interaction are the key factors in the fabrication of the sensor. The Nyquist plot and cyclic voltammograms provided evidence that the BaO-MWCNT/MCPE sensor has caused electrocatalytic oxidation of DIU. Thus, BaO-MWCNT composite material is a viable modifier in an electrochemical sensor. However, the study also evaluated the dearth of published studies on the electrochemical detection of other interfering species, such as amitrole, bentazone, and carbendazim, during real sample analysis. Furthermore, the sensor was efficiently utilized for the electrochemical DIU quantification in soil and water samples. These results emphasize the developed sensor to portray good selectivity, sensitivity, and reliability for DIU determinations.

Fabrication of Flexible Supercapacitor Electrode Materials by Chemical Oxidation of Iron-Based Amorphous Ribbons.

A flexible electrode constructed from Fe-based amorphous ribbons decorated with nanostructured iron oxides, representing the novelty of this research, was successfully achieved in one-step via a chemical oxidation method, using a low concentration of NaOH solution. The growth of metal oxides on a conductive substrate, which forms some metal/oxide structure, has been demonstrated to be an efficient method for increasing the charge transfer efficiency. Through the control and variation of synthetic parameters, different structures and morphologies of iron oxide were obtained, including hexagonal structures with a hollow ball shape and rhombohedral structures with rhombus-like shapes. Structural and morphological characterization methods such as X-ray diffraction and SEM morphology were used on the as-synthesized composite materials. The supercapacitor properties of the as-developed amorphous ribbons decorated with Fe2O3 nanoparticles were investigated by cyclic voltammetry, galvanostatic charge discharge, and electrochemical impedance spectroscopy. The flexible supercapacitor negative electrode demonstrates a specific capacitance of 5.96 F g-1 for the 0.2 M NaOH treated sample and 8.94 Fg-1 for the 0.4 M NaOH treated sample. The 0.2 M treated negative electrodes deliver 0.48 Wh/kg at a power density of 20.11 W/kg, and the 0.4 M treated electrode delivers 0.61 Wh/kg at a power density of 20.85 W/kg. The above results show that these flexible electrodes are adequate for integration in supercapacitor devices, for example, as negative electrodes.

“Soil for Soil Remediation” Strategy Driven on Converting Natural Soils into Fe2O3-CAN-Type Zeolite Composites for Dual Ionic Heavy Metal-Contaminated Soil Remediation: Universality, Synergistic Effects, and Mechanism

Herein, we developed a universal “soil for soil remediation” strategy to utilize soil resources for cation-/anion-type heavy-metal-contaminated soil remediation. The representative natural soils fetched from 12 different areas in China have been universally converted into Fe2O3-CAN (hydroxycancrinite) zeolite composite materials. Furthermore, we discover that due to the presence of exchangeable Na+ and OH– in CAN channels together with the intrinsic surface adsorption function of Fe2O3-CAN, Fe2O3-CAN holds distinctive cation/anion dual ion-exchange functions and strong adsorption capacity, which could synergistically remediate cation-/anion-type HM-contaminated soil. When 25 g/kg Fe2O3-CAN is added into Cd/As polluted soil (100–200 ppm), Cd2+ and AsO2– in soil could be immobilized simultaneously and the Cd/As bioaccumulation in the harvested vegetables is dramatically suppressed with reduction ratios of 48.1–67.0%, effectively reducing the HM enrichment in the phytosphere. Overall, this work confirms the high universality of Fe2O3-CAN synthesis using different types of natural soils and demonstrates that the as-synthesized Fe2O3-CAN composite material can be further effectively used for soil remediation. The “soil for soil remediation” strategy developed here could improve the flexibility and economy of soil remediation, which can be extended to a broad range of locations worldwide.

Silver-Nanoparticle-Decorated g-C3N4/MIL-53(Fe) Nanocomposites: A Pre-Eminent Visible-Light-Driven Photocatalyst toward Multimodal Photocatalytic Applications

Designing a heterostructure photocatalyst material having high porosity with enhanced specific surface area and optoelectrical properties is one of the significant approaches toward the decontamination of hazardous organic contaminants and water-splitting reactions under visible light irradiation. In this study, a silver-nanoparticle-decorated g-C3N4 (ACN)/MIL-53(Fe) photocatalyst was developed having an improved surface area by a facile solvothermal approach. The as-synthesized pure and composite materials are characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and photoluminescence analysis. It is observed that 15% of ACN-20 modified MIL-53 (MACN-15) exhibits improved charge separation between the photoinduced electron and hole pairs which eventually shows the highest photocatalytic applications in rhodamine B (RhB) degradation, photocatalytic Cr(VI) reduction, and photocatalytic hydrogen evolution from water splitting. The optimal photocatalyst (MACN-15) shows 98% of RhB degradation and 95% of Cr(VI) reduction efficiency within 60 min of visible light irradiation. The MACN-15 nanocomposite also exhibits a superior rate of H2 evolution (2.891 mmol g–1 h–1) with a specific conversion efficiency of 14.8%. A possible mechanism is also predicted for the MACN-15 nanocomposite in multimodal photocatalytic applications.

Resource Recycling of Red Soil to Synthesize Fe2O3/FAU-type Zeolite Composite Material for Heavy Metal Removal.

Heavy metal-polluted water is of great concern to human health and the eco-environment. In situ water remediation techniques enabled by highly efficient adsorption materials are of great importance in these circumstances. Among all the materials used in water remediation, iron-based nanomaterials and porous materials are of great interest, benefiting from their rich redox reactivity and adsorption function. Here, we developed a facile protocol to directly convert the widely spread red soil in south China to fabricate the Fe2O3/faujasite (FAU)-type zeolite composite material. The detailed synthesis procedure and synthesis parameters, such as reaction temperature, reaction time, and the Si/Al ratio in the raw materials, have been carefully tuned. The as-synthesized composite materials show good adsorption capacity for typical heavy metal(loid) ions. With 0.001 g/mL Fe2O3/FAU-type zeolite composite material added to different heavy metal(loid)-polluted aqueous solutions (single type of heavy metal(loid) concentration: 1,000 mg/L [ppm]), the adsorption capacity was shown to be 172, 45, 170, 40, 429, 693, 94, and 133 mg/g for Cu (II), Cr (III), Cr (VI), As (III), Cd (II), Pb (II), Zn (II), and Ni (II) removal, respectively, which can be further expanded for heavy metal-polluted water and soil remediation.

Raspberry-like CuWO4 hollow spheres anchored on sulfur-doped g-C3N4 composite: An efficient electrocatalyst for selective electrochemical detection of antibiotic drug nitrofurazone

We report a highly selective and sensitive electrochemical sensor for the determination of nitrofurazone (NZ) based on sulfur-doped graphitic carbon nitride with copper tungstate hollow spheres (Sg–C3N4/CuWO4). Here, a Sg–C3N4/CuWO4 composite was synthesized by a facile ultrasonic method. The physicochemical properties of the composite were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), energy dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS). Then, the surface morphology of the composite material was investigated by field emission scanning electron microscopy (FE-SEM) and high-resolution transmission electron microscopy (HR-TEM). Moreover, the electrochemical activity of the as-synthesized composite material was initially tested using electrochemical impedance spectroscopy (EIS). The electroanalytical techniques namely cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were carried out for the electrochemical studies. The proposed sensor exhibits lower LOD and good sensitivity of about 3 nM and 1.24 μAμM−1 cm−2 to NZ detection. In addition, the Sg–C3N4/CuWO4 modified electrode showed excellent repeatability, reproducibility, long-term storage stability and excellent selectivity. The developed sensor was successfully applied for the determination of NZ in human urine and serum samples and achieved good recovery results.

Ultrasmall Particle Sizes of Walnut-Like Mesoporous Silica Nanospheres with Unique Large Pores and Tunable Acidity for Hydrogenating Reaction.

The large particle sizes, inert frameworks, and small pore sizes of mesoporous silica nanoparticles greatly restrict their application in the acidic catalysis. The research reports a simple and versatile approach to synthesize walnut-like mesoporous silica nanospheres (WMSNs) with large tunable pores and small particle sizes by assembling with Beta seeds. The as-synthesized Beta-WMSNs composite materials possess ultrasmall particulate sizes (70 nm), large radial mesopores (≈30 nm), and excellent acidities (221.6 mmol g-1 ). Ni2 P active phase is supported on the surface of Beta-WMSNs composite materials, and it is found that the obtained composite spherical materials can reduce the Ni2 P particle sizes from 8.4 to 4.8 nm with the increasing amount of Beta seeds, which can provide high accessibilities of reactants to the active sites. Furthermore, the unique large pores and ultrasmall particle sizes of Beta-WMSNs samples facilitate the reduction of the diffusion resistance of reactants due to the short transporting length, thus the corresponding Ni2 P/Beta-WMSNs composite catalysts show the excellent hydrogenating activity compared to the pure Ni2 P/WMSNs catalyst.

Application of WS2-G composite as cathode for rechargeable magnesium batteries

The graphene-supported WS2 composite (WS2-G) was synthesized by the ultra-sonication method. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and field emission scanning electron microscopy (FESEM) showed WS2 had been successfully combined with the graphene. The charge-discharge tests, cyclic voltammetry, and electrochemical impedance spectroscopy were used to study electrochemical properties of as-synthesized composite material. The results showed that the electrochemical properties of graphene-supported WS2 were superior to that of WS2 material. The initial discharge capacity of the graphene-supported WS2 material reached 82 mAh g−1. After 100 cycles, it still had a capacity retention rate of 95%. Enhanced electrochemical performance of graphene-supported WS2 could be attributed due to the synergistic effect between WS2 and highly conductive graphene. The intercalation behavior of Mg2+ is further confirmed by XRD, EDX, and XPS analysis.

Activated Carbon/MnO2 Composites as Electrode for High Performance Supercapacitors

Activated carbon (AC) was synthesized with various weight ratios of manganese dioxide (MO) through a simple hydrothermal approach. The electrochemical performance of the synthesized activated carbon/MnO2 composites was investigated. The effect of the activated carbon/MnO2 (AM) ratio on the electrochemical properties of the activated carbon/MnO2 composites and the pore structure was also examined. The results show that the specific capacitance of the activated carbon material has been improved after the addition of MO. The as-synthesized composite material exhibits specific capacitance of 60.3 F g−1 at 1 A g−1, as well as stable cycle performance and 99.6% capacitance retention over 5000 cycles.

Synthesis of polyaniline/5-sulfosalicylic acid composite and it’s electrochemical properties

Here, we synthesize a composite of polyaniline and 5-sulfosalicylic acid (PANI-SSA) using a chemical oxidative polymerization method. The as-synthesized composite material was characterized using several physico-chemical and electrochemical techniques such as Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), X-ray diffraction (XRD), transmission electron microscopy (TEM), cyclic voltammetry (CV), galvanostatic charge–discharge (GCD), and electrochemical impedance spectroscopy (EIS). The as-synthesized PANI-SSA composite shows much higher capacity of 72 mAh g−1 than the pristine PANI (41 mAh g−1). The composite also shows better cyclic stability and retains capacity almost the same after 1000 galvanostatic charge/discharge cycles. This result demonstrates the importance of PANI-SSA as an electrode material for energy storage applications.

Aluminum promoted sulfidation of ammonium perrhenate: Presence of nanobattery in the ReS2 composite material based memcapacitor

This study demonstrates a new approach to the synthesis of rhenium disulfide (ReS2) in a sulfidation reaction of ammonium perrhenate (NH4ReO4), occurring at room temperature and in water solution. It was found that aluminum (Al) plays a catalytic role in the reaction taking place in low ionic strength solutions. The reaction product is characterized using several analysis techniques, including energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), transmission electron microscopy (TEM), Raman spectroscopy and thermogravimetric analysis (TGA). Furthermore, an interesting observation of both memristive and memcapacitive effects, existence of nanobattery with an electromotive force estimated to be 0.80 V, in a prototypical device based on the as-synthesized ReS2 composite material is presented. This finding shows promise for the implementation of the ReS2 in the next generation memristor technology.

Sonochemical Synthesis of Carbon Dots/Lanthanoid MOFs Hybrids for White Light-Emitting Diodes with High Color Rendering.

Although lanthanoid metal-organic frameworks (Ln-MOFs) have been widely developed for white light-emitting diodes (WLEDs), the color rendering index (CRI) values are still lower than 80. To overcome this limitation, a series of CDs/Ln-MOFs hybrids, namely, CDs-2@Ln-MOF, CDs-3@Ln-MOF, and CDs-4@Ln-MOF containing blue-emitting CDs and yellow-emitting bimetallic [(Eu1.22Tb0.78(1,4-phda)3(H2O)](H2O)2 were prepared via sonication at room temperature to restrict the self-quenching of CDs in composite materials. The as-synthesized composite materials were investigated by Fourier transform infrared, powder X-ray diffraction, transmission electron microscopy, scanning electron microscopy, and photoluminescence. The luminescent color of the materials can be adjusted by varying the amount of CDs and excitation wavelengths. The resulting CDs-3@Ln-MOF achieved excellent CRI up to 93 with the ideal Commission International ed'Eclairage coordinate (0.334, 0.334) and appropriate correlated color temperature (CCT) (5443 K). In addition, the tunable multicolored luminescence based on single and bimetallic EuxTb2-x(1,4-phda)3(H2O)](H2O)2, x = 0, 0.73, 1.22, 1.57, 1.94, and 2, were applied as the luminescent security inks for anti-counterfeiting application through encoding/decoding and rewritable data.

Copper iodide nanoparticles within the organic matrix: an efficient catalyst for the electro-oxidation of formic acid

The synthesis of ultrafine copper (I) iodide (CuI) nanoparticles has been reported using a modified route of ‘in situ polymerization and composite formation (IPCF)’ method (Mallick et al 2007 J. Phys. Condens. Matter 19 196225, Mallick et al 2012 J. Macromol. Sci. B 51 134–141). The CuI nanoparticles with the average size of 10 nm are dispersed within the polyaniline matrix. The as-synthesized composite material was characterized by optical, surface and microscopic techniques. The polymer stabilized CuI nanoparticles has also been applied as a catalyst for the electrochemical detection of formic acid. The cyclic voltammetry and the square wave voltammetry techniques were used in this study for the efficient electro-oxidation of the analyte. The result shows the gradual increase of current intensity due to the increase of formic acid concentration. A moderately good stability and performance has shown by the CuI nanoparticles based device for the electrochemical oxidation of formic acid with the sensitivity and limit of detection values of 0.0197 μA. mM−1. cm−2 and 0.048 mM, respectively.

Green Oxidation of Cyclohexanone to Adipic Acid over Phosphotungstic Acid Encapsulated in UiO-66

A very stable catalyst, phosphotungstic acid (PTA) encapsulated in metal–organic framework UiO-66, was prepared by a simple one-pot solvothermal method. Characterization results show that UiO-66 is quite stable in the catalyst preparation process, and PTA is encapsulated in the cavities of UiO-66 with good dispersity. The as-synthesized composite material exhibited good catalytic activity and excellent reusability for the green oxidation of cyclohexanone to adipic acid (AA). Under mild reaction conditions, the isolated yield of AA was as high as 80.3% without the introduction of any organic solvent or phase transfer agent. The excellent immobilization effect of UiO-66 for PTA is mainly because UiO-66 has a well matched window size to confine PTA molecule in its nanocages.

In-situ synthesis of AlON reinforcing phases in resin bonded Al 2 O 3 composite materials

Abstract AlON reinforced Al2O3 composite materials were prepared from fused corundum, tabular alumina, active Al2O3 powders and phenolic resin through a carbothermal reduction nitridation process. The as-synthesized composite materials are characterized by X-ray diffraction, Scanning electronic microscope and Energy-dispersive X-ray spectroscopy. The results show that the major phase is Al2O3 in the composite materials synthesized at various sintering temperatures. And the in-situ formed AlON reinforcing phases show an evolution, which changes from 21R polytype (Al7O3N5), to γ-AlON (Al5O6N) and finally to φ′-AlON (Al11O15N), with the elevation in sintering temperature. Due to the fact that different AlON crystals are connecting neighboring Al2O3 matrix particles, the physical properties of the as-synthesized composite materials are improved. Based on the conducted characterizations and calculations, AlON phases are formed from the reaction between small quantities of residual carbon from phenolic resin and active Al2O3 powders.

In-situ synthesis and reaction mechanism of β-SiAlON in the Al-Si3N4-Al2O3 composite material

An Al-Si3N4-Al2O3 composite material has been successfully prepared by sintering at 1300°C under nitrogen atmosphere, and X-ray diffraction, scanning electronic microscopy, and electronic differential system were used for its characterization. β-SiAlON with Z=1 (Si5AlON7) appears in the as-synthesized composite material as a reinforcing phase leading to an improvement of the overall physical properties of the Al-Si3N4-Al2O3 composite. The thermal dynamic analysis of the reaction indicates that Al reacts to Al4C3 and Al4O4C. Our thermal dynamic analysis reveals that the addition of Si3N4 to Al4O4C leads to the formation of β-SiAlON.

Ac conductivity investigation of polyindole/poly(vinyl acetate) composites

This paper reports the investigation on ac conductivity, dielectric constant and thermal properties of polyindole/poly(vinyl acetate) composites. As-synthesized composite materials were analyzed through the field effect scanning electron microscope, thermal gravimetric–differential thermal analysis (TG–DTA), differential thermal gravimetry (DTG) and ac conductivity as well as dielectric constant measurements. The ac conductivity of synthesized composites was determined as 1.88 × 10−6 S/cm at frequency 1 MHz (at 373 K). The thermal stability of composites was observed through the TG–DTA analysis. The thermal activation energy was determined from DTG curves.

Importance of Internal Porosity for Glucan Adsorption in Mesoporous Carbon Materials.

To better understand the adsorption of long-chain poly(1 → 4)-β-D-glucans on carbon surfaces as well as interactions responsible for this adsorption, we use a comparative study involving mesoporous carbon-silica composite materials that have been etched to varying degrees and all-atom molecular dynamics simulations. The materials synthesized as part of this etching study consist of an as-synthesized composite material (MCN-MSN), MCN-MSN-0.5 (composite materials consisting of 50% carbon by mass), MCN-MSN-0.3 (composite materials consisting of 70% carbon by mass), and MCN, in which silica etching was conducted using an aqueous ethanolic solution of either NaOH or HF. Data for the adsorption of long-chain glucans to these materials from concentrated aqueous HCl (37 wt %) solution demonstrate a direct relationship between the amount of β-glu adsorption and the magnitude of exposed carbon mesopore surface area, which systematically increases and is also accompanied by an increase in the mesopore size during silica etching. This demonstrates β-glu adsorption as occurring on internal carbon mesopores rather than exclusively on the external carbon surface. These experimental data on adsorption were corroborated by molecular dynamics (MD) simulations of β-glu adsorption to a graphene bilayer separated by a distance of 3.2 nm, chosen to correspond to the carbon mesopore diameter of the experimental system. Simulation results using a variety of β-glu solvent systems demonstrate the rapid adsorption of a β-glu strand on the graphitic carbon surface via axial coupling and are consistent with experimentally observed trends in fast adsorption kinetics. Solvent-mediated effects such as small-scale hydrophobicity and preferential interactions with ions are shown to play important roles in modulating glucan adsorption to carbon surfaces, whereas experimental data on hydrophobically modified silica demonstrate that hydrophobicity in and of itself is insufficient to cause β-glu adsorption from concentrated aqueous HCl solution.

Monodispersed Ag nanoparticles as catalyst: preparation based on crystalline supramolecular hybrid of decamethylcucurbit[5]uril and silver ions.

Monodispersed silver nanoparticles (Ag(0) NPs) have been first prepared on the basis of a postsynthesis via mild reduction from a new crystalline supramolecular hybrid solid assembled from Ag(+) ions and decamethylcucurbit[5]uril (Me10CB[5]). Uniform growth of nearly spherical Ag(0) NPs with an average size of ca. 4.4 nm was observed on the organic Me10CB[5] support to form Ag@Me10CB[5] composite material. The as-synthesized composite material was characterized by a range of physical measurements (PXRD, TGA, XPS, ICP, TEM, etc.) and was further exploited as a heterogeneous catalyst for the reduction of various nitrophenols in the presence of NaBH4. The kinetics of the reduction process was monitored under various experimental conditions. The Ag@Me10CB[5] composite material showed excellent catalytic performance over the reduction reactions and remained active after several consecutive cycles.

Exploring ‘nano filler’ based on oil palm ash in polypropylene composites

This study presents the utilization of oil palm ash (OPA), a siliceous material from the fiber of oil palm biomass, as a nanofiller for the development of polymer nanocomposites. Polypropylene-based polymer nano-composites reinforced with OPA along with a compatibilizer were prepared by a melt-mixing technique, using a double screw extruder. Variations in the mechanical, morphological, and thermal properties with the filler and compatibilizer loading were studied. The best dispersion occurred in the polymer nano-composites for which the interactions between the polymer matrix and nanosized OPA appeared to be the highest. The particle size and the dispersion of the oil palm ash within the matrix were determined by transmission electron microscopy. The as-synthesized composite materials were typically characterized by tensile and impact test methods. The morphology of the composite materials was studied by scanning electron microscopy. The thermal properties determined by thermogravimetric analysis (TGA) showed enhanced thermal stability of a series of composite materials. Also, melting studies were carried out by differential scanning calorimetry.