Sharif Digital Repository

Conductive self -electrical stimuli bioactive scaffolds could be used the potential for peripheral nerve regeneration with the maximum efficiency. To produce such conductive self-electrical stimuli bioactive scaffolds, chopped spun piezoelectric nanofibers of polyvinylidene fluoride/mesoporous silica nanoparticle (PVDF/MCM41) are prepared and incorporated in gellan/polyaniline/graphene (gellan/PAG) nanocomposites which have been previously prepared by incorporation of polyaniline/graphene (PAG) nanoparticles in gellan gel at 80 °C. Highly conductive binary doped polyaniline/graphene nanoparticles are prepared by chemical oxidative polymerization of aniline monomer using in-suite... 

Abstract: The use of thermoelectric fabrics for powering wearable devices is expected to become widespread soon. A thermoelectric fabric was prepared by coating nanocomposite of polyaniline/graphene nanosheets (PANI/GNS) on a fabric. Four samples of the fabric containing different wt% of GNS (0.5, 2.5, 5, and 10) were prepared. To characterize the samples, Fourier transform infrared (FTIR) spectra, attenuated total reflectance-Fourier transform infrared (AT-FTIR) spectra, field-emission scanning electron microscopy (FE-SEM), electrical conductivity and Seebeck coefficient measurements were used. The electrical conductivity increased from 0.0188 to 0.277 S cm−1 (from 0.5 to 10 wt% of the GNS... 

In this work, a comparative study has been performed on two ex-situ and one in-situ doping of titania photoanodes with reduced graphene oxide. The presence of finely dispersed reduced graphene oxide facilitates electron transport and reduces electron-hole recombination resulting in a better performance of doped titania photoanodes. It was found that in-situ doping, i.e. introduction of graphene oxide in solution together with titania precursor was the most performant case of graphene doping. This result was obvious by studying dye-sensitized solar cells based on such doped photoanodes but was also and mainly analytically demonstrated by subjecting the obtained materials to characterization... 

The development of graphene-based nanocomposites is currently the issue of enormous research interest. Recent advancements have exhibited that semiconductor/graphene nanocomposites can be purposed as a promising new category of catalysts for the heterogeneous photocatalytic treatment of wastewaters. Since semiconductor/graphene nanocomposites have been found efficient in degradation of organic pollutants, photodegradation of phenol and phenolic compounds as hazardous contaminants in aqueous solution has been most widely investigated by these aforementioned nanocomposites. In the present review, after introduction on the properties and the different synthesis methods of semiconductor/graphene... 

The current research focuses on suggesting a new potential application of polymeric materials for capacitor applications by focusing on polystyrene (PS)/ethylene-α-octene copolymer (EOC) blends. Polymeric materials have high dielectric strength (≈ 200 for PS), good processability, and flexibility. However, their low dielectric constants make them not suitable for capacitor applications. Therefore, suggesting a method for enhancing their dielectric constant accompanied by low tan δ proposes an excellent substitute for commonly used ceramic dielectrics. The current article investigates the control of the dielectric properties of PS/EOC blends by manipulating the graphene nanoplatelets (GNPs)... 

A novel ultrasensitive modified electrode was fabricated with a graphene nanosheets and carbon nanospheres (GNS-CNS)-based nanocomposite film as a powerful platform. Pt nanoparticles (PtNPs) were simply electrodeposited onto the GNS-CNS-coated glassy carbon electrode creating a PtNPs/GNS-CNS hybrid nanocomposite modified electrode. Scanning electron microscopy, energy dispersive X-ray spectroscopy and linear sweep voltammetry (LSV) techniques were used for the characterization of the prepared modified electrode. The results of investigation of electrochemical response characteristics of cefepime (CP) revealed a considerable improvement in the oxidation peak current of CP on PtNPs/GNS-CNS/GCE... 

Porous nanocomposite hydrogels were prepared using CaCO3 particles as solid porogens. The hydrogels were prepared by polymerization and grafting of acrylamide and 2-acrylamido-2-methylpropane sulfonic acid onto the starch in the presence of CaCO3 and graphene oxide. CaCO3 solid porogens were then removed by washing with acid and porous structures were obtained. The prepared hydrogels were used as adsorbents for methylene blue as a model cationic dye; and a very high adsorption capacity, up to 714.29 mg g-1, was obtained. Kinetics and isotherms of adsorption and the effect of porosity of hydrogel as well as other experimental conditions were also investigated. The prepared adsorbents were... 

A series of reduced graphene oxide/ZnxCd1-xS (RGO/ZnxCd1-xS) nanocomposites (0 < x < 1) with different ratios of Zn/Cd were synthesized via a facile hydrothermal route under optimized experimental conditions and were carefully characterized by various techniques. Because very little is known about the morphology, specific surface area, and crystal phase effects of RGO/ZnxCd1-xS crystals on their photoresponsivity, field-emission scanning electron microscopy (FE-SEM), BET surface area analysis and X-ray diffraction (XRD) data were studied to investigate their effects on photoactivity. Based on the results, a crystal phase transition from a cubic phase in RGO/Zn0.9Cd0.1S to a hexagonal... 

The present work reports the synthesis of a Pt-modified NiO–Al2O3 nanocomposite derived from graphene-supported layered double hydroxide (Pt–NiO/G) and demonstrates its catalytic activity. The resulting Pt–NiO/G nanocomposite was characterized by FT-IR, XRD, FE-SEM, TEM and XPS techniques and used for catalytic reduction of p-nitrophenol (P-NP) to p-aminophenol (P-AP). The influence of graphene on catalytic activity was comparatively considered by preparation of Pt–NiO nanoparticles derived from layered double hydroxide. The superior catalytic performance of Pt–NiO/G was ascribed to the synergistic effect between Pt and NiO. Furthermore, reduction of P-NP was considered to follow a... 

Graphene nanoplatelets with different surface functional groups and polarity were prepared by Hummer's method and electrochemical exfoliation of graphite in two aqueous acids. The XRD, FTIR and sedimentation tests performed to characterize the polarity of the prepared graphenes. The highest polarity was associated with the sample prepared by Hummer's method and the sample synthesized by electrochemical exfoliation in nitric acid medium showed the moderate polarity. Meanwhile, the sample prepared in sulfuric acid medium showed the lowest polarity. Then thermoplastic polyurethane (TPU)/graphene nanocomposite films were fabricated with solvent exchange method. While the dispersion state and... 

The room temperature polar vapor sensing behavior of a graphene-TiS3 heterojunction material and TiS3 nanoribbons is described. The nanoribbons were synthesized via chemical vapor transport (CVT) and their structure was investigated by scanning electron microscopy, high resolution transmission electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, Raman and Fourier transform infrared spectroscopies. The gas sensing performance was assessed by following the changes in their resistivities. Sensing devices were fabricated with gold contacts and with lithographically patterned graphene (Gr) electrodes in a heterojunction Gr-TiS3-Gr. The gold contacted TiS3 device has a... 

In this research, the effect of adding graphene-based aerogel ((G)A) nanoparticles on the tensile and fatigue behavior of the epoxy polymer was investigated. Specimens of nanocomposites were prepared by adding 0.05, 0.1, 0.2, 0.5, 1, and 2 wt.-% (G)A nanoparticles to the epoxy polymer. Tensile tests revealed that the 0.1 wt.-% graphene-based aerogel/ epoxy ((G)A/E) nanocomposites had the highest increase in tensile strength with 19 % growth compared to neat epoxy. Also, the tensile modulus increased by 15 % in the 0.5 wt.-% (G)A/E nanocomposites. A substantial improvement in fatigue life of the epoxy polymer was observed on adding 0.1 wt.-% (G)A nanoparticles. For instance, the fatigue life... 

The impacts of dopant nanoparticles, graphene nanosheets (GNSs) and cobalt decorated-graphene nanosheets (CoGNSs), were studied in relation to the wettability and rheological behavior in low-Ag lead-free SAC0307 (Sn–0.3Ag–0.7Cu) solder paste. The solidification range of the solders was evaluated using differential scanning calorimetry. Phase identification in the solder bulk and interface of the solder and copper substrate was carried out by X-ray diffraction and energy-dispersive X-ray spectroscopy. Spreading properties and reactive wetting behavior along with the rheological properties of the solders were also studied. Results showed that the addition of both nanoparticles did not... 

We present a procedure for simultaneous deposition of enzyme-laden chitosan/reduced graphene oxide (rGO) film by electrophoretic deposition (EPD) for fast and efficient detection of glucose. The role of rGO nanosheets is studied on the EPD kinetics of the enzyme-laden suspensions. Investigating the performance of the biosensor by electrochemical techniques indicates its high sensitivity (9700 μA.mM−1.cm−2), low limit of detection (4 µM), and suitable selectivity. © 2021 Elsevier B.V  

CdS/TiO2/graphene (CTG) nanocomposite thin films were synthesized by a facile production route. The TiO2/graphene (TG) nanocomposite was initially fabricated by sol-gel method in such a way that TiO2 nanoparticles loaded on graphene oxide (GO) sheet via photocatalytic process. Then, CdS nanoparticles were deposited on the TG thin film by successive ion layer adsorption and reaction process (SILAR) approach. Based on atomic force microscopy (AFM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analyses, the TG thin film possessed a larger surface area as compared with the pure TiO2 thin film due to presence of graphene sheet. UV/visible spectroscopy exhibited... 

TiO2-graphene (TiO2-GR) nanocomposites were synthesized using photocatalytic reduction method. TiO2-GR nanocomposites were thereafter doped with noble metals (Pt and Pd) by chemical reduction of the corresponding cations. The samples were characterized by different techniques. The addition of GR to TiO2 decreases the crystalline size of TiO2 due to the homogeneous dispersion of the TiO2 nanoparticles on GR sheets and prevention of coagulation of TiO2 nanoparticles during synthesis process. In addition, the surface area of TiO2 was increased by addition of GR and deposition of noble metals which helps to prevent agglomeration of graphene sheets and TiO 2 nanoparticles. Red shifts to the... 

Dynamic and static fracture properties of Graphene Sheets (GSs) and Carbon nanotubes (CNTs) with different sizes are investigated based on an empirical inter-atomic potential function that can simulate nonlinear large deflections of nanostructures. Dynamic fracture of GSs and CNTs are studied based on wave propagation analysis in these nanostructures in a wide range of strain-rates. It is shown that wave propagation velocity is independent from strain-rate while dependent on the nanostructure size and approaches to 2.2×10 4m/s for long GSs. Also, fracture strain shows extensive changes versus strain-rate, which has not been reported before. Fracture stress is determined as 115GPa for GSs and... 

Titanium nitride/graphene nanocomposite as an anode material of lithium ion batteries has been fabricated through the reaction of TiCl4 and NaN3 in supercritical benzene medium followed by ammonia treating at 1000 °C for 10 h. The synthesized TiN/G nanocomposite depicts rate-dependent behavior in such a way that it shows specific capacity of 115 mAh g−1 when is cycled at higher rate (1.6 C) while it shows 76 mAh g−1 when is cycled initially at lower rate (0.2 C) and is subsequently subjected to higher rate (1.6 C). Moreover, TiN/G anode demonstrates capacity retention of 112%, 100%, and 70% after 250 cycles at charge/discharge rates of 1.6, 0.7, and 0.2 C, respectively. This unusual behavior... 

A simple and low-cost electrochemical deposition method is used to prepare reduced graphene oxide/polypyrrole/Cu2O-Cu(OH)2 (RGO/PPy/Cu2O-Cu(OH)2) ternary nanocomposites as the electrode material for supercapacitor application. First, graphene oxide-polypyrrole (GO/PPy) nanocomposite is electrochemically synthesized on Ni foam by electro-oxidation of pyrrole monomer in an aqueous solution containing GO and Tiron. Subsequently, the GO/PPy film is converted to the corresponding reduced form (RGO/PPy) by an effective and eco-friendly electrochemical reduction method. Then, a thin layer of Cu2O-Cu(OH)2 is formed on RGO/PPy film by chronoamperometry. The RGO/PPy/Cu2O-Cu(OH)2 nanocomposite is...