Graphene oxide (GO)-supported polyoxometalates (POMs) have been considered as promising electrode materials for energy storage applications due to their ability to undergo fast and reversible redox reactions. Herein, vanadomanganate-GO composites (K7MnIVV13O38.18H2O-GO with 2:1 and 4:1 ratio) were investigated for use as potential electrode materials in supercapacitors (SCs). The K7MnIVV13O38.18H2O (MnV13) was synthesized and anchored on GO through electron transfer interaction and electrostatic interaction to make the composite electrodes for the present study. All synthesized electrode materials were fully characterized by various techniques, e.g., Fourier Transform Infrared (FTIR) Spectroscopy, Powder X-ray Diffraction (XRD), Scanning Electron Microscopy/Energy Dispersive X-ray Spectroscopy (SEM/EDS) and High Resolution-Transmission Electron Microscopy (HR-TEM). The electrochemical properties of MnV13/GO composites with different MnV13/GO ratios were investigated by two-electrode cyclic voltammetry (CV) and galvanostatic charge/discharge (GCD) in different electrolytes. The MnV13/GO composite of ratio 2:1 in 1 M LiCl electrolyte and that of ratio 4:1 in 1 M Na2SO4 electrolyte showed significant specific capacitance values of 269.15 F/g and 387.02 F/g, respectively and energy density of 37.38 Wh/kg and 53.75 Wh/kg, respectively for a scan rate of 5 mV/s. Interestingly, the 1:1 (MnV13/GO) composite in 1 M Na2SO4 and 1 M LiCl electrolytes showed very low specific capacitance values as the deposition of MnV13 on GO was not sufficient, as indicated by FTIR and SEM. Thus, it is evident that the specific capacitance value of these composite materials depends on the amount of MnV13 deposited on GO and these composite materials exhibit the potential to improve the performance of GO-based SCs. 相似文献
The present study demonstrates the use of a simple and versatile melt-compounding route to prepare NaClO4-containing poly(ethylene oxide) PEO/clay nanocomposites combining excellent mechanical properties with a competitive level of the ionic conductivity. The nanostructure and the resulting thermal, mechanical and conductive properties of the salt-containing PEO/clay nanocomposites were found to be highly sensitive to the clay type, i.e. aspect ratio of the clay, to the presence of an organic modifier in the intergallery spacing, and to the salt concentration. The highest increase of the shear storage modulus is obtained in the presence of single silicate layers, thus an exfoliated nanostructure, having a high aspect ratio. These structures are only obtained with an (polar) organically modified clay (Cloisite 30B), regardless of the presence of salt. The use of non-organically modified clays (Cloisite Na+ and Laponite) resulted in intercalated nanocomposites, with only a minor improvement in stiffness. A strong interaction between the Na+ from NaClO4 and the Cloisite 30B silicate layers might be responsible for an increased PEO crystallinity and resultant additional increase in stiffness. A mechanism is proposed whereby the Na+ ions are drawn away from the PEO phase, to be complexed by the silicate layers, or even ion-exchanged with modifier cations. The addition of clay did not greatly affect the ion conductivity below the melt temperature of PEO. At higher temperatures, the nanocomposites displayed only slightly lower conductivities compared to the PEO/NaClO4 complex, due to the presence of the clay platelets. 相似文献
Graphene oxide (GO) was synthesized by Hummers method. GO and tungsten oxide (WO3) composites were successfully prepared by deposition of WO3 on GO surface to make efficient visible light catalyst. Scanning electron microscopy of pure GO revealed that GO films are folded with kinked and wrinkled edges. The interspaces layers are partially filled by WO3 nanoparticles with their less wrinkled edges and smooth surface of composite. Moreover, composite sheets are thin and transparent which allow easy penetration of light. EDS showed the presence of C, O, and W in GO/WO3 composites with no impurity. UV-Vis diffused reflectance spectra showed red shift with the increase in WO3 contents. Raman spectra of GO and GO/WO3 composite show G and D bands. These bands reduced in intensity in composite sample due to removal of oxygenated functional groups with some new peaks of WO3. FT-IR confirmed successful oxidation of graphite into GO with reduction in GO because oxide-related bond groups decrease after reduction. The transmittance peaks of WO3 in composite sample are appeared indicating W-O-C linkages. The highest visible light activity of the composite is due to easy penetration of light with deposition of WO3, low band gap, and new linkages. 相似文献
Aqueous solution properties of polyethylene oxide–block-polypropylene oxide–block-polyethylene oxide TBP [(PEO)103(PPO)39(PEO)103] were studied in the presence of sodium salts with different anions (NaI, NaBr, NaCl, NaF, Na2SO4, Na3PO4) to investigate unimer-to-micelle transition [critical micelle concentration (CMC), critical micellization temperature (CMT)],
micelle size and the phase separation (cloud point). This TBP, due to its very hydrophilic (80% PEO) nature does not form
micelles at ambient temperatures. Micellization can be induced much below its CMT in water on addition of sodium salts having
different anions. Analytical methods viz. fluorescence, FTIR and dynamic light scattering (DLS) were used to monitor the salt-induced
micellization. The hydration of respective anion and resultant contribution to its salting-out effect was found to be the
governing factor in promoting micellization. The presence of salt decreases the CMC, CMT and phase separation temperature.
The salts affect the aggregation process in agreement with an order mentioned in Hofmeister series. 相似文献
Two simple and effective methods, “click” chemistry and supramolecular interactions, are demonstrated here to synthesize well-defined poly(l-lactide) (PLLA) functionalized graphene oxide (GO) sheets. We provide a simple method to introduce azide groups on GO sheets by the ring opening reaction of sodium azide with the epoxide groups of GO. The GO-N3 sheets can easily undergo “click” reaction with alkyne-terminated PLLA by “grafting onto” method to produce GO/PLLA composites with high grafting ratio and exfoliated structure. Interestingly, GO-N3 can be grafted with oxygen-containing polymers such as PLLA, polymethyl methacrylate (PMMA) or polyethylene oxide (PEO) via supramolecular interactions between the azide groups and these oxygen atoms on polymers, producing GO/polymer composites with low grafting ratio and intercalated structure. These “grafting onto” methods are useful to produce a variety of GO/polymer composites with different structure via “click” reaction or supramolecular interactions, which have potential applications in material science. 相似文献
In order to further improve the tribological performance of glass fiber reinforced epoxy (GF/EP) composites, highly flexible, binder‐free, molybdenum trioxide MoO3 nanobelt/graphene oxide (GO) film (f‐MoO3‐GO) is prepared by a hydrothermal method. Herein, f‐MoO3‐GO is adopted to modify GF/EP composites prepared through the vacuum‐assisted resin transfer molding method. The neat GF/EP and MoO3‐GO modified GF/EP composites are also fabricated for comparison. The tribological performance is performed using a ball‐on‐disc (“steel‐on‐polymer”) configuration under a dry sliding condition. The coefficient of friction is reduced from 0.61 for neat GF/EP composites down to 0.23 for f‐MoO3‐GO modified GF/EP (f‐MoO3‐GO/GF/EP) composites and the anti‐wear performance is improved by more than four times. The worn surface morphological observation for the composite samples is used to explain the possible wear micro‐mechanisms. The wear reducing effect of the f‐MoO3‐GO/GF/EP composites can be assigned to the increased self‐lubricating effect of f‐MoO3‐GO. With the combined advantageous properties of the used individual components, these unique composites can be used for many other applications. 相似文献
A self-assembly polymerization process was used to prepare graphene oxide/boron carbide (GO/B4C) composite powders, spark plasma sintering (SPS) was used to fabricate reduced graphene oxide/boron carbide (rGO/B4C) composites at 1800 °C and 30 MPa with a soaking time of 5 min. The effects of rGO addition on mechanical properties of the composites, such as Vickers hardness, flexural strength and fracture toughness, were investigated. The results showed that GO/B4C composite powders were successfully self-assembled and a network structure was formed at high GO contents. The flexural strength and fracture toughness of rGO/B4C composites were 643.64 MPa and 5.56 MPa m1/2, respectively, at 1 and 2.5 wt.% rGO content, corresponding to an increase of 99.11% and 71.6% when compared to B4C ceramics. Uniformly dispersed rGO in rGO/B4C composites played an important role in improving their strength and toughness. The toughening mechanisms of rGO/B4C composites were explained by graphene pull-out, crack deflection and bridging. 相似文献
Herein, we report a successful synthesis of supramolecularly assembled polyaniline/silver oxide/graphene oxide composite (PANI/Ag2O/GO) for enhanced NO2 gas sensing application. The PANI/Ag2O/GO composite was synthesized by facile stirring followed by an ultrasonication process. The prepared material was characterized by different techniques such as x-ray diffraction, field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy and Raman-scattering spectroscopy. The detailed analysis revealed that the average crystallite sizes of PANI/Ag2O and PANI/Ag2O/GO composites were found to be 37.37 nm and 41.55 nm, respectively. FESEM and TEM analysis showed coral-like rough-surfaced and extensively agglomerated morphology for PANI and ultrathin flexible sheet-like morphology for GO. Ag2O nanoparticles with diameters 20–30 nm were well incorporated in the GO sheets and PANI matrix in the case of PANI/Ag2O/GO composites. The synthesized materials were used to make resistive sensor devices that had a high response to NO2 gas. The fabricated sensors were examined at various temperatures to obtain the optimal sensing temperature. The fabricated NO2 gas sensor device based on PANI/Ag2O/GO composite exhibited a highest sensitivity of 5.85 for 25 ppm at an optimized temperature (100 °C) as compared to the pure PANI (2.5) and PANI/Ag2O composite (3.25). Further, the fabricated sensor device based on PANI/Ag2O/GO composite was also examined at different NO2 gas concentrations. 相似文献
Polyamide (PA) NF membranes are synthesized on a hollow fiber support by the interfacial polymerization (IP) of piperazine (PIP) and trimesoyl chloride (TMC). Then, GO is coated on the PA layer to decorate the NF membrane surface (denoted GO/PA-NF). This strategy aims to improve the hydrophilicity, chlorine resistance and separation stability of the membrane. The optimization, chemical composition, morphology, and hydrophilicity of the synthesized GO/PA-NF membrane are characterized. Results indicate that the optimized GO/PA-NF in terms of rejection rate and flux are with 0.05 wt% GO. The rejection of GO/PA-NF for Na2SO4 and MgSO4 is 99.4% and 96.9%, respectively. Even if the GO/PA-NF is immersed in 1000 ppm NaClO solution for 48 h, the NF membrane still maintains stable salt rejection. The developed NF membranes exhibit excellent treatment performance on dying wastewater. The permeate flux and rejection of GO/PA-NF toward Congo red solution are determined to be 44.2 L/m2h and 100%, respectively. Compared with the PA membrane, GO/PA-NF presents a higher rejection for Na2SO4 (99.4%) and a lower rejection for NaCl (less than 20%), which shows that the NF membranes have a better divalent/monovalent salt separation performance. This study highlights the superior performance of GO/PA-NF and shows its high potential for application in wastewater treatment. 相似文献
High‐performance nanocomposites of NaCMC with GO are produced by solution casting. FESEM images reveal a good homogeneous dispersion of GO in the NaCMC matrix. The composite formation is facilitated by H‐bonding interaction between GO and NaCMC. Tg of the composites increases with increasing GO concentration. The storage modulus (G′) exhibits a maximum 174% increase over NaCMC at 1 wt% GO. The mechanical properties of the composites exhibit highest increase of tensile stress and Young's modulus of 188 ± 4% and 154 ± 11%, respectively, for 1 wt% GO. Analysis of Young's modulus (Ey) data using the Halpin‐Tsai equation suggests that the Ey data are close to the unidirectional orientation at >0.5 wt% GO, indicating more efficient load transfer at these compositions.
The present study reports the synthesis of composite films comprising PEO/Na2PtCl6 complex and their deposition onto fused silica substrates via the dip-coating method. Chemical, crystallographic, and thermal characterizations are carried out to confirm the incorporation of Na2PtCl6 and PEO matrix into the films. The transmittance of the PEO film is initially high and decreases subsquently with an increase in Na2PtCl6 content. The optical band-gap energy of the composite films decreases exponentially from 4.62 to 3.79 eV with the increase in Na2PtCl6 content. Furthermore, in the normal dispersion region, the refractive index of the PEO film decreases from 2.00 to 1.670 as the wavelength increases from 400 to 700 nm. The refractive index values increase with an increase in the concentration of Na2PtCl6 in the PEO film up to 8 wt.%. The incorporation of Na2PtCl6 into the PEO matrix increases the electrical conductivity because of the combined enhancement of the PEO conductivity and increase i Na2PtCl6. These findings suggest that PEO/Na2PtCl6 complex composite films have potential applications in UV-shielding and optoelectronic devices. 相似文献