Comparative and Efficient Ammonia Gas Sensing Study with Self-assembly-Synthesized Metal Oxide-SiC Fiber-Based Mesoporous SiO2 Composites.

Self-assembled-assisted ternary nanocomposite In2O3-SiC, CuO2-SiC, and MnO2-SiC semiconductors were mixed with SiO2 to enable gas sensing using cyclic voltammetry. The results of TEM (transm In2O3-SiC-SiO2 ion electron microscopy), X-ray diffraction spectroscopy, and Raman spectra analysis affirm the closeness of few layers between SiO2 and SiC in In2O3-SiC, MnO2-SiC, and CuO2-SiC. Among the electrochemical impedance spectra curves of the nanocomposites, none of the samples had a semicircle profile, which indicates the existence of a higher charge-transfer resistivity behavior between the electrolyte and the sample electrode with charge carrier and transport effects, which is related to the well-developed porous structure of synthesized composites. CuO2-SiC-SiO2 and MnO2-SiC-SiO2 showed high resistivity and a quite significant response for NH3 gas at room temperature. While there was a response for NH3 gas for In2O3-SiC-SiO2, the sensor showed a low response for the gas. From the sensing test, correspondences between the chemical structure of the sensor and the molecular structure of the gases have been found. The surface reactions between the sensor surface and the gas with a pore structure, along with the electron receiver/donor phase are observed from the results of gas sensor tests, and all factors are determining the precise state. Finally, the adsorption of NH3 molecules and the alteration of the electronic resistance of In2O3-SiC-SiO2, MnO2-SiC-SiO2, and CuO2-SiC-SiO2 were presented that include various thicknesses of charge to represent which are achieved by the connection with the substrates and the particles.

3D Modeling of Silver Doped ZrO2 Coupled Graphene-Based Mesoporous Silica Quaternary Nanocomposite for a Nonenzymatic Glucose Sensing Effects.

We described the novel nanocomposite of silver doped ZrO2 combined graphene-based mesoporous silica (ZrO2-Ag-G-SiO2,) in bases of low-cost and self-assembly strategy. Synthesized ZrO2-Ag-G-SiO2 were characterized through X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDX), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), Raman spectroscopy, Nitrogen adsorption-desorption isotherms, X-ray photoelectron spectroscopy (XPS), and Diffuse Reflectance Spectroscopy (DRS). The ZrO2-Ag-G-SiO2 as an enzyme-free glucose sensor active material toward coordinate electro-oxidation of glucose was considered through cyclic voltammetry in significant electrolytes, such as phosphate buffer (PBS) at pH 7.4 and commercial urine. Utilizing ZrO2-Ag-G-SiO2, glucose detecting may well be finished with effective electrocatalytic performance toward organically important concentrations with the current reaction of 9.0 × 10-3 mAcm-2 and 0.05 mmol/L at the lowest potential of +0.2 V, thus fulfilling the elemental prerequisites for glucose detecting within the urine. Likewise, the ZrO2-Ag-G-SiO2 electrode can be worked for glucose detecting within the interferometer substances (e.g., ascorbic corrosive, lactose, fructose, and starch) in urine at proper pH conditions. Our results highlight the potential usages for qualitative and quantitative electrochemical investigation of glucose through the ZrO2-Ag-G-SiO2 sensor for glucose detecting within the urine concentration.

Effect of Impurities Control on the Crystallization and Densification of Polymer-Derived SiC Fibers.

The polymer-derived SiC fibers are mainly used as reinforcing materials for ceramic matrix composites (CMCs) because of their excellent mechanical properties at high temperature. However, decomposition reactions such as release of SiO and CO gases and the formation of pores proceed above 1400 °C because of impurities introduced during the curing process. In this study, polycrystalline SiC fibers were fabricated by applying iodine-curing method and using controlled pyrolysis conditions to investigate crystallization and densification behavior. Oxygen and iodine impurities in amorphous SiC fibers were reduced without pores by diffusion and release to the fiber surface depending on the pyrolysis time. In addition, the reduction of the impurity content had a positive effect on the densification and crystallization of polymer-derived SiC fibers without a sintering aid above the sintering temperature. Consequently, dense Si-Al-C-O polycrystalline fibers containing ß-SiC crystal grains of 50~100 nm were easily fabricated through the blending method and controlled pyrolysis conditions.

New Design of Active Material Based on YInWO4-G-SiO2 for a Urea Sensor and High Performance for Nonenzymatic Electrical Sensitivity.

In the present study, electrochemical sensing for urea was proposed utilizing graphene-based quaternary nanocomposites YInWO4-G-SiO2 (YIWGS). These YIWGS nanocomposites were utilized due to their exceptionally delicate determination of urea with the lowest detection limit (0.01 mM). These YIWGS composites were developed through a simple self-assembly method. From physical characterization, we found that the YIWGS composites are crystalline in nature (powdered X-ray diffraction), and Fourier transform infrared (FTIR) spectroscopy analysis provided the surface functionality and bonding. Scanning electron microscopy (SEM) studies indicated the morphology characteristics of the as-synthesized composites and the high-resolution transmission electron microscopy (HRTEM) image supported the formation of cubic or hexagonal morphology of the YIW nanocomposites. The YIWGS sensor showed a great electroanalytical sensing performance of 0.07 mM urea with a sensitivity of 0.06 mA cm-2, an expansive linear range of 0.7-1.5 mM with a linear response (R2 1/4 0.99), and an eminent reaction time of around 2 s. It also displayed a good linear response toward urea with negligible interferences from normal coinciding species in urine samples.

New modeling of 3D quaternary type BaCuZnS-graphene-TiO2 (BCZS-G-T) composite for photosonocatalytic hydrogen evolution with scavenger effect.

For the efficient evolution of hydrogen, we designed a 3D quaternary BaCuZnS-graphene-TiO2 (BCZS-G-T) composite by an ultrasonic method. Herein, we prepared a quaternary material to minimize the bandgap energy and size. We characterized the "as-prepared" composites by X-ray diffraction (XRD), scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) analysis, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectroscopy (DRS), photoluminescence (PL) spectroscopy, and electrochemical impedance spectroscopy (EIS). The high hydrogen evolution was attributed to the 3D quaternary BCZS-G-T composite with small bandgap energy because of its high photoelectron recombination properties. In addition, we demonstrated the combination effects with photocatalytic and sonocatalytic treatments with a scavenger. This work highlights the potential application of quaternary graphene-based composites in the field of energy conversion.

Novel Micro and Nanostructure of a AgCuInS2-Graphene-TiO2 Ternary Composite for Photocatalytic CO2 Reduction for Methanol Fuel.

Photocatalytic CO2 reduction into hydrocarbon fuels over photocatalysts has hypothetical and reasonably developed into a trendy exploration topic. In this study, the progress of the quaternary nanocomposite containing a graphene-based catalyst was reported; this was fabricated using the hydrothermal technique. The analysis of physical characteristics of the nanocomposite confirmed the interaction between all parts. The quaternary nanocomposite containing the graphene-based catalyst was utilized for carbon dioxide reduction to methanol (CH3OH) under light irradiation. Titanium dioxide (TiO2) and the quaternary nanocomposite of AgCuInS2 were monotonously spread on the graphene exterior. This nanomaterial showed superior activity compared with TiO2 and the binary composite for CO2 conversion, and the obtained result indicates that the synthesized ternary composite enhaces the properties of the photocatalyst in the reduction process.

Comparative Study of Electrochemical Biosensors Based on Highly Efficient Mesoporous ZrO2-Ag-G-SiO2 and In2O3-G-SiO2 for Rapid Recognition of E. coli O157:H7.

Here, we reported an innovative and electrochemical biosensor for the rapid detection of Escherichia coli O157:H7. We fabricated the mesoporous ZrO2-Ag-G-SiO2 (ZAGS) and In2O3-G-SiO2 (IGS) sensors, and cyclic voltammetry (CV) was employed to detect the bacteria. The development of these portable sensors addresses the challenges of conventional time-consuming and more expensive laboratory-based analyses. Hence, the biosensors were highly selective to detect E. coli. The sensor could recognize an individual E. coli cell in 1 µL of sample volume within 30 s. E. coli live cells tied down on sample nanoparticles worked toward the definite acquirement of E. coli. The high thickness of negative charge on the surface of E. coli cells effectively regulated the concentration of dominant part charge carriers in the mesoporous channel, allowing a continuous check of E. coli concentration in a known sample. The signal current decreased linearly, while the E. coli concentration increased from 1.0 × 101 to 1.0 × 1010 CFU/mL. ZAGS and IGS biosensors could detect E. coli in the range from 101 to 1010 CFU/mL. ZAGS and IGS biosensors in this investigation showed great specificity, reproducibility, stability, and selectivity and are expected to have a great impact on applications in the detection of foodborne pathogens.

Hybrid of Graphene based on quaternary Cu2ZnNiSe4 -WO3 Nanorods for Counter Electrode in Dye-sensitized Solar Cell Application.

A novel nanohybrid of graphene-based Cu2ZnNiSe4 with WO3 nanorods (G-CZNS@W) was successfully synthesized via a simple hydrothermal method to use as a counter electrode (CE) for dye-sensitized solar cells (DSSCs). The characterization technique confirmed the structural and morphologies of the G-CZNS@W nanohybrid, which could show rapid electrons transfer pathway through the WO3 nanorods. Moreover, the as-fabricated G-CZNS@W nanohybrid exhibited synergetic effect between G-CZNS and a WO3 nanorod, which could affect the electrocatalytic activity towards triiodide reaction. The nanohybrid exhibits an excellent photovoltaic performance of 12.16%, which is higher than that of the standard Pt electrode under the same conditions. The G-CZNS@W nanohybrid material as CE thus offers a promising low-cost Pt-free counter electrode for DSSC.

The double perovskite structure effect of a novel La2CuNiO6-ZnSe-graphene nanocatalytic composite for dye sensitized solar cells as a freestanding counter electrode.

Currently, the development of sensitized solar cells (DSSCs) with high power conversion efficiency and low cost is a major challenge in the academic and industrial fields. In order to enhance the current efficiency of dye-sensitized solar cells (DSSCs), a perovskite graphene-La2CuNiO6-ZnSe (G-LCN-ZS) as a counter electrode (CE) was introduced in this study via a conventional microwave treatment. A DSSC with 15% G-LCN-ZS CE achieved a high-power conversion efficiency up to 11.05% under AM 1.5G solar simulation, which is one of the highest reported efficiencies for ternary oxide-based graphene DSSCs. The G-LCN-ZS CE nanocomposites exhibit excellent catalytic activity towards the I3-/I- redox couple due to the positive synergistic effect between LCN-ZS nanoparticles and graphene sheets. Moreover, the graphene-based materials can provide a fast diffusion pathway for the electrolyte. In this paper, we have shown that alternative materials with high energy conversion efficiency can be used in future applications.

An eco-friendly synthesized mesoporous-silica particle combined with WSe2-graphene-TiO2 by self-assembled method for photocatalytic dye decomposition and hydrogen production.

To address the limitations of titanium dioxide (TiO2) and expand the applicability of the photocatalytic activity of TiO2,WSe2 and silica, an eco-friendly, self-assembled method for combining a silica precursor with a WSe2-graphene-TiO2 composite with cetyltrimethylammonium bromide (CTAB) as surface active agents is proposed. Firstly, for the main target, the photocatalytic degradation of organic dye solutions with different initial pH levels and catalyst dosages under visible light irradiation was surveyed. The as-synthesized sample exhibited highly efficient photocatalytic effects for the treatment of the SO dye solution in the optimal conditions of this study, which included a solution with a pH level of 11 and 0.05-gram dosage of the catalyst. Secondly, previous photocatalytic hydrogen production studies reported markedly better outcomes with SiO2/WSe2-graphene-TiO2 than with the binary WSe2-graphene and ternary WSe2-graphene-TiO2 composites under ambient conditions with and without 20% methanol sacrificing reagents. The SiO2/WSe2-graphene-TiO2 composite is promising to become a potential candidate for photocatalytic performance that performs excellently as well as offer an efficient heterosystem for hydrogen production.

Novel synthesis of WSe2-Graphene-TiO2 ternary nanocomposite via ultrasonic technics for high photocatalytic reduction of CO2 into CH3OH.

In the present work, we report the development of a WSe2-Graphene-TiO2 ternary nanocomposite via ultrasonic techniques and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. The band-gap of the WSe2-Graphene-TiO2 was estimated to be about 1.62 eV which is suitable for photodegradation process under under ultraviolet UV/Visible light irradiation. The photocatalytic potential of nanocomposites is investigated for CO2 reduction to CH3OH. WSe2-G-TiO2 with an optimum loading of graphene of 8 wt% showed the high photoactivity, gaining a total CH3OH yield of 6.3262 µmol g-1 h-1 after 48 h. This excellent photoreduction activity is owing to the progressive synergistic relation between WSe2/TiO2 and graphene components in our heterogeneous system.

Optical and photocatalytic properties of novel heterogeneous PtSe2-graphene/TiO2 nanocomposites synthesized via ultrasonic assisted techniques.

Novel material PtSe2-graphene/TiO2 nanocomposites were successfully synthesized through a facile ultrasonic assisted method. The prepared composites were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) with an energy dispersive X-ray (EDX),transmission electron microscopy (TEM), Raman spectroscopic analysis, UV-vis absorbance spectra and UV-vis diffuse reflectance spectra (DRS) analysis were obtained. The catalytic behavior was investigated through the decomposition of rhodamine B (Rh.B) as a standard dye. Enhanced photocatalytic activities were observed by increasing the weight% of graphene in the PtSe2-graphene/TiO2 nanocomposites. We observed that the coupling of TiO2 with PtSe2-graphene alter the optical properties by observing a precise band gap in the visible range.

Fullerene modification CdSe/TiO2 and modification of photocatalytic activity under visible light.

CdSe, CdSe-TiO2, and CdSe-C60/TiO2 composites were prepared using sol-gel method, and their photocatalytic activity was evaluated by measuring the degradation of rhodamine B solutions under visible light. The surface area, surface structure, crystal phase, and elemental identification of these composites were characterized by nitrogen adsorption isotherms, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), and UV-visible (vis) absorption spectrophotometry. XRD showed that the CdSe-C60/TiO2 composite contained a typical single and clear anatase phase. SEM of the CdSe-C60/TiO2 composites revealed a homogenous composition in the particles. EDX revealed the presence of C and Ti with strong Cd and Se peaks in the CdSe-C60/TiO2 composite. The degradation of dye was determined by UV-vis spectrophotometry. An increase in photocatalytic activity was observed and attributed to an increase in the photoabsorption effect by fullerene and the cooperative effect of the CdSe. The repeatability of photocatalytic activity was also tested in order to investigate the stability of C60 and CdS-C60/TiO2 composites.