Fabrication of super-stretchable and electrical conductive membrane of spandex/multi-wall carbon nanotube/reduced graphene oxide composite

Hybrid conductive fillers (hybrids) are prepared through simultaneous chemical reduction of the graphene oxide and acid-treated multi-wall carbon nanotube in the presence of hydrazine. Subsequently, the thermoplastic spandex-based composite membranes with different hybrids contents are fabricated by solution casting method. At 20 wt% loading of hybrids, the membrane displays both super-stretchability (387% of elongation at break) and good electrical conductivity (49.5 S cm^?1). Further investigations of the electromechanical behaviour show that the strain sensitivity is dependent on hybrids content. Therefore, the as-prepared spandex/hybrids composite membranes are promising materials for the fabrication of wearable electronics and stretchable energy storage/conversion devices.     

二维导电材料/柔性聚合物复合材料基可穿戴压阻式应变传感器的研究进展

可穿戴应变传感器在人体运动检测、健康监测、可穿戴电子设备和柔性电子皮肤等新兴领域具有极大的应用前景。近年来,由二维（2D）导电材料和柔性聚合物基体组成的可穿戴压阻式应变传感器具有较高的灵敏度、良好的拉伸性和柔韧性、优异的耐久性、可调的应变传感性和易加工等特点,受到广泛关注。基于此,本文对基于2D导电材料/柔性聚合物复合材料（2D-CPC）的可穿戴压阻式应变传感器的类型、传感机理、性能指标、影响因素及应用等进行了综述,并对其未来发展趋势进行了展望。     

Superior ammonia sensing properties of PET-supported polyaniline/reduced graphene oxide/zinc ferrite ternary nanocomposite thin film at room temperature

This article introduces a ternary nanocomposite-based flexible thin film ammonia sensor developed on transparent polyethylene terephthalate (PET) substrate in the well-known in situ chemical oxidative polymerization technique. The nanocomposite consists of three different materials: polyaniline (PANI), reduced graphene oxide (rGO), and zinc ferrite (ZF). Keeping the PANI amount constant, seven PANI/rGO/ZF (PRZ) samples are produced by performing stoichiometric variation between rGO and ZF. Later on, various structural, morphological, and spectroscopic analysis of all the composite materials is accomplished with field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), and ultraviolet–visible spectroscopy (UV–Vis). The sensing performance of the as-produced sensors toward ammonia (NH₃) is examined in the concentration range from 250 ppb to 100 ppm. The study reveals the excellent sensing ability of the PRZ3 sensor (rGO = 30%, ZF = 20%) achieving minimum and maximum responsivity values of ~51% and ~1052%, respectively, at the lowest (250 ppb) and highest (100 ppm) concentration of ammonia. The sensor also exhibits admirable repeatability, good dynamic responsivity, rapid response (t_res ~2.9–5 s), moderately faster recovery (t_rec ~37.9–69.7 s), superb linearity against ppm variation (R² ~ 0.989), low detection limit (~123 ppb), and exceptional selectivity toward ammonia. The substrate temperature variation divulges that room temperature (30°C) is the ideal temperature for getting outstanding responsivity of the sensor. The study is further accompanied by humidity variation in the incoming air and bending flexibility test of the substrate. A compulsory and legitimate model regarding the sensing mechanism is presented at the end.     

Synergistically improved thermal stability and electromagnetic interference shielding effectiveness (EMI SE) of in-situ synthesized polyaniline/sulphur doped reduced graphene oxide (PANI/S-RGO) nanocomposites

Polyaniline (PANI) and its composite with sulphur doped reduced graphene oxide (S-RGO) have been successively synthesized via in-situ chemical oxidative polymerization of aniline in presence of 10 wt. % S-RGO nanosheets. Physico-chemical analyses of the synthesized nanomaterial was performed with various characterization techniques such as X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Spectroscopy (EDS), Atomic Force Microscopy (AFM) and Thermogravimetric analysis/Differential Scanning Calorimetry (TGA/DSC). The results interpreted from the various characterizations confirm the doping of RGO with sulphur as well as strong interaction of PANI nanofibers and S-RGO nanosheets. TG/DSC curves confirm the enhanced thermal stability of polyaniline/sulphur doped reduced graphene oxide (PANI/S-RGO) nanocomposites with heat resistance index (T_HRI) of 155.2 °C in comparision to pure PANI (T_HRI = 145.3 °C) at a filler loading of 10 wt. %. TGA validates that thermal stability of PANI/S-RGO nanocomposite improves by 6–7 °C than pure PANI in terms of weight loss percentage at a temperature of 1117 °C. However DSC analysis confirms that PANI/S-RGO retains its structural integrity and conformity to temperatures as high as 900 °C beyond which the polymer composite starts to degrade. The electromagnetic interference shielding effectiveness (EMI SE) of PANI and PANI/S-RGO nanocomposites were measured via open-ended coaxial probe set-up connected to a Vector Network Analyser (VNA) at a broadband frequency range of 1–20 GHz (1000–20000 MHz). For EMI SE measurements the various nanomaterials were incorporated into paraffin wax and made into composite pellets of thickness 5 mm by solution casting technique. The dielectric properties, electrical conductivity and EMI SE were all greatly enhanced for the PANI/S-RGO/Paraffin composite pellets. The as synthesized PANI/S-RGO/Paraffin composite pellets exhibited highest EMI SE of ?22.5 dB (>99%) as compared to ?15.89 dB of PANI/Paraffin composite pellets. The prepared composite pellets revealed an absorption dominant mechanism of shielding with highest SE_A of ?14.6 dB for PANI/S-RGO/Paraffin composite pellets.     

Microwave-assisted green synthesis of Ag/reduced graphene oxide nanocomposite as a surface-enhanced Raman scattering substrate with high uniformity

A nanocomposite of silver nanoparticles/reduced graphene oxide (Ag/rGO) has been fabricated as a surface-enhanced Raman scattering (SERS) substrate owing to the large surface area and two-dimensional nanosheet structure of rGO. A facile and rapid microwave-assisted green route has been used for the formation of Ag nanoparticles and the reduction of graphene oxide simultaneously with L-arginine as the reducing agent. By increasing the cycle number of microwave irradiation from 1 and 4 to 8, the mean diameters of Ag nanoparticles deposited on the surface of rGO increased from 10.3 ± 4.6 and 21.4 ± 10.5 to 41.1 ± 12.6 nm. The SERS performance of Ag/rGO nanocomposite was examined using the common Raman reporter molecule 4-aminothiophenol (4-ATP). It was found that the Raman intensity of 4-ATP could be significantly enhanced by increasing the size and content of silver nanoparticles deposited on rGO. Although the Raman intensities of D-band and G-band of rGO were also enhanced simultaneously by the deposited Ag nanoparticles which limited the further improvement of SERS detection sensitivity, the detectable concentration of 4-ATP with Ag/rGO nanocomposite as the SERS substrate still could be lowered to be 10⁻¹⁰ M and the enhancement factor could be increased to 1.27 × 10¹⁰. Furthermore, it was also achievable to lower the relative standard deviation (RSD) values of the Raman intensities to below 5%. This revealed that the Ag/rGO nanocomposite obtained in this work could be used as a SERS substrate with high sensitivity and homogeneity.     

Forward osmosis water desalination: Fabrication of graphene oxide-polyamide/polysulfone thin-film nanocomposite membrane with high water flux and low reverse salt diffusion

This paper investigates the synthesis of graphene oxide (GO)-incorporated polyamide thin-film nanocomposite (TFN) membranes on polysulfone substrate for forward osmosis applications. The GO nanosheets were embedded into polyamide layer using different concentrations (0.05?0.2 wt%). The results represented the alteration of polyamide surface by GO nanosheets and enhancing the surface hydrophilicity by increasing the GO loading. The results showed that the water flux for 0.1 wt% GO embedded nanocomposite (TFN) membrane was 34.7 L/m² h, representing 90% improvement compared to the thin-film composite, while the salt reverse diffusion was reduced up to 39%.     

Effect of phase transitions on the electrical properties of polymer/carbon nanotube and polymer/graphene nanoplatelet composites with different conductive network structures

Multi‐walled carbon nanotube (MWCNT)‐ and graphene nanoplatelet (GNP)‐filled high‐density polyethylene (HDPE) composites with dispersed and segregated network structures were prepared by solution‐assisted mixing. Simultaneous DC conductivity and differential scanning calorimetry were used to measure electrical conductivity during composite thermal phase transitions. It was found that the conductive network is deformed during melting and rebuilt again during annealing due to the re‐agglomeration of nanofillers. The rebuilding of the structure is significantly affected by the original network structure and by the shape and loading of the nanofillers. Both deformation and reorganization of the network lead to drastic changes in the conductivity of the composites. The crystallization process also affects the conductive network to some extent and the subsequent volume shrinkage of the polymeric matrix after crystallization results in a further decrease in the resistivity of HDPE/GNP composites. Classical electrical percolation theory combined with a kinetic equation is used to describe the conductivity recovery of composites during annealing, and the results are found to be in good agreement with experimental data. © 2017 Society of Chemical Industry     

Fabrication and its characteristics of metal-loaded TiO2/SnO2 thick-film gas sensor for detecting dichloromethane

This study investigated sensitivity of the gas sensor to chemical warfare agents with the various operating temperatures and catalysts. The nano-sized SnO₂ powder mixed with metal oxide (TiO₂) was doped with transition metals (Pt, Pd and In). Thick film of nano-sized SnO₂ powder and TiO₂ was prepared by screen-printing method onto Al₂O₃ substrates with platinum electrode and chemical precipitation method. The physical and chemical properties of sensor material were investigated by SEM/EDS, XRD and BET analyzers. The measured sensitivity to simulant chemical toxic gas is defined as the percentage of resistance of value equation, (R_a − R_g/R_a), that of the resistance (R_air) of SnO₂ film in air and the resistance (R_gas) of SnO₂ film in dichloromethane. The best sensitivity and selectivity of these thick-film sensor were shown with 1 wt.% Pt and 5 wt.% TiO₂ for dichloromethane toxic gas at the operating temperature of 250 °C.     

Ni/MgO catalyst prepared via dielectric-barrier discharge plasma with improved catalytic performance for carbon dioxide reforming of methane

A Ni/MgO catalyst was prepared via novel dielectric-barrier discharge (DBD) plasma decomposition method. The combined characterization of Brunauer-Emmett-Teller measurement, X-ray diffraction, hydrogen temperature-programmed reduction and transmission electron microscopy shows that DBD plasma treatment enhances the support-metal interaction of Ni/MgO catalyst and facilitates the formation of smaller Ni particles. Sphere-like Ni particles form on plasma treated Ni/MgO catalysts. The plasma treated Ni/MgO catalyst shows a significantly improved low temperature activity and good stability for CO₂ reforming of methane to syngas.     

Effects of substitution for carbon black with graphene oxide or graphene on the morphology and performance of natural rubber/carbon black composites

In this study, nanosheets including graphene oxide (GO) and reduced graphene oxide (rGO), were incorporated into natural rubber (NR), to study the effects of substituting GO or rGO for carbon black (CB) on the structure and performance of NR/CB composites. The morphological observations revealed the dispersion of CB was improved by partially substituting nanosheets for CB. The improvements in static and dynamic mechanical properties were achieved at small substitution content of GO or rGO nanosheets. With substitution of rGO nanosheets, significant improvement in flex cracking resistance was achieved. NR/CB/rGO (NRG) composites has a much lower heat build‐up value compared with NR/CB/GO (NG) composites at a high load of nanosheets. However, both GO and rGO tended to aggregate at a high concentration, which led to the poor efficiency on enhancing the dynamic properties, or even deteriorate the performance of rubber composites. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41832.     

MOFs诱导中空Co3O4/CdIn2S4合成及光催化CO2还原性能研究

光催化二氧化碳转化技术,不仅可以利用取之不尽用之不竭的太阳光能,而且可将二氧化碳转化为高附加值的碳基燃料,受到研究者们的广泛关注。实验设计合成了新颖的中空结构的Co₃O₄/CdIn₂S₄异质结光催化剂。两种半导体的高效耦合作用极大地促进了光生载流子分离,同时形成更多暴露活性位点。基于异质结独特的结构优势,表现出高效的CO₂还原性能,5% Co₃O₄/CdIn₂S₄ 的CO生成速率达74 μmol·g^-1·h^-1,与单体CdIn₂S₄相比,不仅活性得到很大提升,同时CO选择性达到100%。     

Development of thin‐film composite membranes for carbon dioxide and methane separation using sulfonated poly(phenylene oxide)

Novel membranes based on sulfonated poly (phenylene oxide) (SPPO) was developed. SPPO membranes in the hydrogen form were converted to metal ion forms. The effect of exchange with metal ions including monovalent (Li⁺, Na⁺, K⁺), divalent (Mg²⁺, Ba²⁺, Ca²⁺) and trivalent (Al³⁺) ions was investigated in terms of permeation rate and permeation rate ratios for CO₂ and CH₄ gases. Both dense homogeneous membranes and thin‐film composite (TFC) membranes were studied for their gas separation characteristics. The effect of membrane preparation conditions and operating parameters on the membrane performance were also investigated. The selectivity of the TFC membrane increased as the cationic charge density increased as a result of electrostatic cross‐linking. TFC membrane of very high selectivity was achieved by coating a thin layer of SPPO‐Mg on a PES substrate. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 735–742, 2000     

Preparation and studies of transparent conductive monolayers of multiwall carbon nanotubes on quartz and flexible polymer with the use of modified Langmuir technique

An improved Langmuir method is described and applied to produce transparent, conductive and flexible single layer of multiwall carbon nanotubes. This paper presents properties of multiwall carbon nanotubes spread on water subphase and in a form of Langmuir–Schaefer layers on a quartz plate and on flexible polymeric foil. The results show very high homogeneity of the monolayers on a very large area obtained with the use of the proposed modified Langmuir method and indicate their relatively high radiation transmission and electrical conductivity. Laser scanning confocal and scanning electron microscopic images of the layers are presented. The microscopic visualization of the nanolayers is supported by spectroscopic studies (transmittance, photoacoustics) in the range from ultraviolet to mid-infrared. Moreover, electric measurements (current versus voltage characteristics) of the carbon material on the polymeric foil are presented.The obtained results of the investigated multiwall carbon nanotubes are discussed in a view of potential application in optoelectronics.     

Adsorptive interaction of bisphenol A with mesoporous titanosilicate/reduced graphene oxide nanocomposite materials: FT-IR and Raman analyses

Nanocomposite materials containing graphene oxide have attracted tremendous interest as catalysts and adsorbents for water purification. In this study, mesoporous titanosilicate/reduced graphene oxide composite materials with different Ti contents were employed as adsorbents for removing bisphenol A (BPA) from water systems. The adsorptive interaction between BPA and adsorption sites on the composite materials was investigated by Fourier transform infrared (FT-IR) and Raman spectroscopy. Adsorption capacities of BPA at equilibrium, q _e (mg/g), decreased with increasing Ti contents, proportional to the surface area of the composite materials. FT-IR observations for fresh and spent adsorbents indicated that BPA adsorbed onto the composite materials by the electrostatic interaction between OH functional groups contained in BPA and on the adsorbents. The electrostatic adsorption sites on the adsorbents were categorized into three hydroxyl groups: Si-OH, Ti-OH, and graphene-OH. In Raman spectra, the intensity ratios of D to G band were decreased after the adsorption of BPA, implying adsorptive interaction of benzene rings of BPA with the sp² hybrid structure of the reduced graphene oxide.     

Energy efficient methane-to-syngas conversion with low H2/CO ratio by simultaneous catalytic reactions of methane with carbon dioxide and oxygen

By simultaneous reactions of methane with CO₂ and O₂ over NiO-CaO catalyst under certain reaction conditions, it is possible to convert methane into syngas with low H₂/CO ratio (1 2/CO <2) at above 95% conversion, with 100% CO selectivity and above 90% H₂ selectivity and also with very high CO productivity without catalyst deactivation due to coking for a long period, in a most energy efficient and safe manner, requiring little or no external energy.     

Adsorption and reactivity during low temperature oxidation of carbon monoxide on Au/TiO2 catalysts studied by rapid response mass spectrometry

The adsorption and reaction of CO, CO₂ and O₂ on TiO₂ and Au/TiO₂ have been studied using a mass spectrometric method which can detect processes occurring on a time scale of seconds. Adsorption of CO on TiO₂ at 300 K is rapidly reversible and less on reduced samples than oxidised ones indicating that the adsorption sites are oxide ions. The amount adsorbed reversibly on reduced Au/TiO₂ is less still, consistent with enhanced reduction, but additional amounts adsorb irreversibly at a slower rate. The amount of CO₂ adsorbed under similar conditions is also greater on TiO₂ than reduced Au/TiO₂ and approximately one order of magnitude greater than that of CO. However, adsorption of O₂ is undetectable on the time scale of the measurement. Exposure of Au/TiO₂ to mixtures of CO and O₂ results in near instantaneous generation of CO₂ although its appearance is attenuated by adsorption. Adsorption of CO occurs concurrently in a way similar to that seen with CO alone except that the amount of the more slowly adsorbed form seems less. This suggests that it is the form utilised in catalysis. Oxygen uptake beyond that generating CO₂ is appreciable during the initial stages of exposure to reaction mixtures and this capacity is enhanced if one or other reactant is removed and then reintroduced, possibly due to the generation of reducible interface sites. It is concluded that the remarkable activity of Au/TiO₂ for CO oxidation at ambient temperature resides in a very high turnover frequency on sites at the interface between the metal and oxide. This revised version was published online in June 2006 with corrections to the Cover Date.     

Stability of Ni/SiO2-ZrO2 catalysts towards steaming and coking in the dry reforming of methane with carbon dioxide

Ni/SiO₂-ZrO₂ catalysts with Ni loadings of 1 to 13 wt-% were prepared, characterized by elemental analysis, X-ray diffraction, N₂ sorption, temperature programmed oxidation, temperature programmed reduction, and tested for their activity and stability in the dry reforming of methane with carbon dioxide at 850 °C, gas hourly space velocity of 6000 and 1800 h^–1 and atmospheric pressure. The SiO₂-ZrO₂ support as obtained through a simple and efficient sol-gel synthesis is highly porous (A_BET = 90 m²·g^–1, d_P = 4.4 nm) with a homogeneously distributed Si-content of 3 wt-%. No loss of Si or formation of monoclinic ZrO₂, even after steaming at 850 °C for 160 h, was detectable. The catalyst with 5 wt-% Ni loading in its fully reduced state is stable over 15?h on-stream in the dry reforming reaction. If the catalyst was not fully reduced, a reduction during the early stages of dry reforming is accompanied by the deposition of up to 44 mg·g^–1carbon as shown by experiments in a magnetic suspension balance. Rapid coking occurs for increased residence times and times-on-stream starting at 50 h. The Ni loading of 5 wt-% on SiO₂-ZrO₂ was shown to provide an optimal balance between activity and coking tendency.     

Regeneration of a vanadium pentoxide supported activated coke catalyst-sorbent used in simultaneous sulfur dioxide and nitric oxide removal from flue gas: Effect of ammonia

A vanadium pentoxide supported activated coke (V₂O₅/AC) catalyst-sorbent has been reported to be very active for simultaneous removal of SO₂ and NO under dry conditions at temperatures of 200 °C and below. Regeneration of the SO₂-captured catalyst-sorbent is a key step in operation of such a process, which influences the catalyst-sorbent's SO₂ and NO removal activities, lifetime, as well as recovery of sulfur. Due to limited information in this regard, this paper studies thermal regeneration of a V₂O₅/AC catalyst-sorbent with emphases on the effect of atmosphere. The optimum regeneration temperature is found to be 380 °C in an Ar stream and 300 °C in a 5% NH₃/Ar stream. Compared to the fresh V₂O₅/AC, the V₂O₅/ACs regenerated in Ar show lower SO₂ adsorption capacities and higher NO removal activities, while the regenerated V₂O₅/ACs by 5% NH₃/Ar show higher and stable SO₂ adsorption capacities and higher NO removal activities. Two types of reactions occur during the regeneration: reduction of the adsorbed sulfur species by carbon to SO₂ and CO₂, and oxidation of carbon by oxygen in the V₂O₅/AC to CO₂. The carbon consumption of the latter is much more than that of the former in an Ar atmosphere, but fully suppressed by the presence of 5% NH₃. Detailed analysis and characterization of the V₂O₅/AC subjected to the regenerations are presented.     

Hydrothermal synthesis of carbon/vanadium dioxide core-shell microspheres with good cycling performance in both organic and aqueous electrolytes

Carbon/vanadium dioxide (C/VO₂(B)) core-shell microspheres were prepared by a one-step hydrothermal process and characterized by X-ray diffraction and scanning electron microscopy. The electric cycling performance of C/VO₂(B) in organic and LiCl aqueous electrolytes was evaluated by the galvanostatic method and by cyclic voltammetry, respectively. The results showed that the product had very stable cycling performance in both types of electrolytes compared to pure VO₂(B).