rGO Loading Research Articles

Novel flexible chemiresistive ammonia sensors based on rGO/ZIF-8 composites deposited on conductive graphite sheets

This work presents novel investigations on room temperature chemiresistive ammonia (NH3) gas sensing capability of composite materials based on reduced graphene oxide (rGO) and ZIF-8 metal organic framework (MOF), deposited on flexible graphite substrate. These rGO/ZIF-8 composites synthesized via a facile one-pot wet chemical route were found to exhibit a fast, highly sensitive and reversible response over successive exposure cycles towards various concentrations of NH3. The enhanced response is attributable to the synergistic performance of the appreciably conductive rGO and the highly porous ZIF-8. ZIF-8 with its high specific surface area, microporous structure and hydrophobicity, serves to provide greater gas adsorptive capacity as well as resistance to effects of ambient moisture. rGO, on the other hand, has limited specific surface area due to π-π restacking of its sheets but it is capable of providing a conductive template to the hybrid material. Consequently, the NH3 gas sensing performance parameters of rGO/ZIF-8 were measured to be exceedingly better than those of bare rGO and ZIF-8 synthesized separately. A response of 15.98 % was recorded towards 10 ppm NH3 with response/recovery times as 2.8/6 s for the rGO/ZIF-8 composites. The enhanced gas sensing performance is credited to the formation of hierarchical pore structure which allows for greater adsorption at the micropore sites and faster diffusion through the mesopores. The effect of rGO loading in the hybrid materials was also assessed. The composite materials exhibited appreciable stability with respect to ambient aging. The adsorption behaviors and the resultant gas sensing mechanisms have also been discussed for the investigated materials.

Low level carbon monoxide detection using chemically reduced graphene oxide deposited ZnO nanorods

Carbon monoxide (CO) is a toxic and extremely dangerous gas commonly produced from partial combustion of fossil fuels from automobiles, industries and power plants, etc. Prolonged inhalation of CO with higher concentration (150–200 ppm) causes convulsions, respiratory arrest and even may lead to death. Therefore, a low-cost highly sensitive CO sensor with low detection limit is needed for environmental and biomedical applications. A resistive CO gas sensor was fabricated using zinc oxide nanorods (ZnO NRs). The sensor sensitivity, response, and detection limit have been enhanced by depositing reduced graphene oxide (rGO). The maximum sensitivity was obtained with 25 µl rGO loading at ∼190 °C operating temperature. The sensor demonstrated high selectivity towards the interfering gases like nitric oxide, acetone, alcohol and ammonia. rGO loaded ZnO NRs based CO gas sensor exhibited sensitivity 0.9 ppm-1 with lower limit of detection ∼14.3 ppb.

Effective degradation of tetracycline under visible light by microwave-assisted reflux synthesis of ZnO/MoS2/rGO ternary nanocomposites

ZnO@MoS2 and conducting rGO based ternary nanocomposites were synthesized by a bottom-up microwave-assisted reflux method and effectively investigated for the photocatalytic degradation of tetracycline hydrochloride (TCH) antibiotic. The XRD, EDAX and XPS results corroborates the formation of nanostructure composite with high phase purity. The ZnO nanorods are well grafted on the curled configuration of layered MoS2 and thin surfaced rGO sheets as visualised from HR-TEM analysis. Upon addition of rGO, there is a significant decrease in the bandgap and improved visible light response in the ternary nanocomposites is elucidated by UV–visible Diffuse Reflectance Spectroscopy (UV-DRS) analysis. The suppression in photo-induced electron/hole pair recombination and allowing easy charge transport of ZnMG-50 were evidenced from photoluminescence (PL) and photo-electrochemical impedance (photo-EIS) spectroscopy. From BET and BJH analysis, the enhancement in surface area and pore volume by loading of rGO (SBET = 264.794 m2/g and 0.548 cm3/g). The optimized ZnMG-50 nano-photocatalyst possess a superior photocatalytic performance with higher removal efficiency of 92.18 % was achieved at pH level 10, catalyst dosage 40 mg and TCH concentration 20 ppm within 180 min under illumination. The degradation process compiles a pseudo-first order reaction with a kinetic rate constant of 0.01365 min−1. The nonstop generation of hydroxyl (˙OH) and superoxide (O2˙-) reactive species were beneficial for free electrons in the active participation, which remains as a core factor in the degradation process. The detailed study on ZnMG-50 nanocomposite substantiated to be an efficient noble metal-free synthetic catalyst for enhanced photocatalytic degradation of antibiotics.

Sunlight driven photocatalytic degradation of organic pollutants by solvothermally synthesized rGO-BiVO4 nanohybrids

This study reports photocatalytic degradation of organic dyes by rGO-BiVO4 nanohybrids. rGO- BiVO4 nanohybrids were solvothermally prepared with different rGO loading (1.5, 3 and 6 %) and their structural, optical and photocatalytic properties were investigated. Effect of rGO loading on photocatalytic dye degradation was studied and the factors responsible were analyzed. Structural analysis was done using XRD and Raman analyses which clearly showed monoclinic phase of the BiVO4. FESEM images showed sub-micron spheres of BiVO4 along with sheet-like structures corresponding to rGO. A slight change in the band gap was observed from 2.2 eV for BiVO4 to around 2 eV for the rGO-BiVO4 nanohybrids. Band to band transitions as well as the transitions from the defect bands were observed from the PL spectra. Photocatalytic degradation studies of organic pollutant MB under natural sunlight showed 3 % rGO-BiVO4 to be the best photocatalyst which degraded 88.4 % of MB in 80 min with rate constant of 0.0244 min−1. It was observed that for obtaining a maximum catalytic efficiency an optimum loading of rGO proved to be best. In either case of higher or lower loading of rGO showed a lower degradation performance. Amongst the samples synthesized 3 % rGO loading was found to be the optimum rGO loading to have the lowest band gap (2 eV) as well as the reduced recombination that has resulted in highest photocatalytic efficiency under solar irradiation.

Robust, Flexible, and Superhydrophobic Fabrics for High-Efficiency and Ultrawide-Band Microwave Absorption

Microwave absorption (MA) materials are essential for protecting against harmful electromagnetic radiation. In this study, highly efficient and ultrawide-band microwave-absorbing fabrics with superhydrophobic surface features were developed using a facile dip-coating method involving in situ graphene oxide (GO) reduction, deposition of TiO2 nanoparticles, and subsequent coating of a mixture of polydimethylsiloxane (PDMS) and octadecylamine (ODA) on polyester fabrics. Owing to the presence of hierarchically structured surfaces and low-surface-energy materials, the resultant reduced GO (rGO)/TiO2-ODA/PDMS-coated fabrics demonstrate superhydrophobicity with a water contact angle of 159° and sliding angle of 5°. Under the synergistic effects of conduction loss, interface polarization loss, and surface roughness topography, the optimized fabrics show excellent microwave absorbing performances with a minimum reflection loss (RLmin) of −47.4 dB and a maximum effective absorption bandwidth (EABmax) of 7.7 GHz at a small rGO loading of 6.9 wt%. In addition, the rGO/TiO2-ODA/PDMS coating was robust, and the coated fabrics could withstand repeated washing, soiling, long-term ultraviolet irradiation, and chemical attacks without losing their superhydrophobicity and MA properties. Moreover, the coating imparts self-healing properties to the fabrics. This study provides a promising and effective route for the development of robust and flexible materials with microwave-absorbing properties.

Utilizing multicriteria decision‐making approach for material selection in hybrid polymer nanocomposites for energy‐harvesting applications

AbstractFlexible and cost‐effective poly(vinylidene fluoride) (PVDF)‐based composites having excellent piezo performance are quite interesting for developing actuators, sensors, and nanogenerators. In this work, a hybrid PVDF‐based nanocomposite consisting of a fixed quantity of titanium dioxide (TiO2) and varying quantities of reduced graphene oxide (rGO) for increased mechanical and piezoelectric performance is reported for the first time. Compared to pure PVDF, there is a significant enhancement in mechanical properties for hybrid nanocomposites. The highest piezoelectric voltage as well as current values of 10.2 V and 0.78 μA are recorded for a hybrid nanocomposite containing 1 wt% of rGO for continuous finger‐tapping operation. A multicriteria decision‐making (MCDM)‐based material selection and optimization technique called TODIM is applied, and a sensitivity study is carried out to select the best material for mechanical energy harvesting applications. A hybrid nanocomposite based on PVDF‐TiO2 with 1% rGO loading is the most suitable material according to the TODIM (an acronym in Portuguese for Interactive Multicriteria Decision Making) approach.Highlights PVDF‐TiO2‐rGO nanocomposites are fabricated by solvent casting. TODIM optimization technique is applied for the best material selection among samples. Material ranking consistency shows the reliability of the TODIM method. Conductive rGO increases interfacial polarization, resulting in enhanced ε values. An increment of 88% and 104% in tensile strength and elastic modulus, respectively.

Colorful graphene-based wearable e-textiles prepared by co-dyeing cotton fabrics with natural dyes and reduced graphene oxide

In addition to the functionality of electronic textiles (e-textiles), their aesthetic properties should be considered to expand their marketability. In this study, premordanted cotton fabrics were co-dyed with reduced graphene oxide (rGO) and natural dyes to develop ecofriendly and colorful graphene-based wearable e-textiles. The color attributes of the textiles were analyzed in terms of the dyeing conditions, namely, rGO loading, mordant type, and natural dye type. The lightness of the dyed samples increased in the order of cochineal < gardenia blue < rhubarb. Regardless of the natural dye and rGO loading, the lightness of the fabrics mordanted with Fe was lower than that with Al and Cu. Moreover, the rhubarb- and gardenia blue-dyed fabrics exhibited broad chroma and hue dispersions, indicating the strong impact of the dyeing conditions. With increasing rGO loading, the chroma of the rhubarb-dyed fabrics substantially decreased, resulting in decreased color saturation. The initial greenish-blue color of the gardenia blue-dyed fabrics gradually changed to yellowish-green and then yellow. Regardless of the natural dye, drastic overall color changes were observed, with average values of 7.60, 11.14, 12.68, and 13.56 ΔECMC(2:1) at increasing rGO loadings of 1, 3, 5, and 7% owb, respectively.

Flexible and stretchable polyester@reduced graphene oxide composite fabric for tunable electromagnetic absorption

The widespread application of 5 G wireless communication and flexible electronic devices has put forward new demands for electromagnetic (EM) absorbing materials. In this work, a flexible composite fabric was successfully prepared by using polyester (PET) knitted fabric as an elastic scaffold and subsequently anchoring reduced graphene oxide (rGO) through a simple impregnation-drying coating method. Regulating the concentration of graphene oxide (GO) impregnation solution can effectively control the rGO loading content for adjusting the EM parameters of PET@rGO composite fabric. When the concentration is 2.0 mg/mL, the as-prepared PET@rGO exhibits the optimum reflection loss (RL) value of −24.53 dB at 12.4 GHz and a corresponding effective absorption bandwidth (EAB, RL≤−10 dB) of 3.20 GHz (9.20–12.40 GHz). The impressive absorption property attributed to the synergistic effect of impedance matching and dielectric loss originated from the three-dimensional (3D) conductive network on fabric interlaced structures. More importantly, stretching PET@rGO composite fabrics to different deformations can dynamically adjust the EM absorption properties while maintaining the knitted structure. This work demonstrates an efficient avenue for the rational design of next-generation EM absorbing fabric, showing latent applications in flexible functional electronics.

ZnO nanorod and rGO based nanocomposite decorated with Au nanoparticles for enhanced UV photodetection

A comprehensive analysis of a hydrothermally prepared Au nanoparticle decorated nanocomposite of reduced graphene oxide (rGO) and a ZnO nanorod (NR) for possible use as a UV photodetector is presented. The effect of rGO loading in ZnO and incorporation of Au decoration in the best combination of rGO/ZnO for possible enhancement of a photocatalytic effect are experimented. X-ray diffraction, scanning electron microscopy, energy diffraction, and UV-Vis spectroscopy are done for morphological, structural, and optical attribute analysis of the prepared materials. An increase in photocurrent is seen from 2.19 nA to 6.14 mA in dark and UV environments (370 nm) at 5 V bias voltage for the Au decorated nanocomposite, which is found to be better among the experimented composites. The responsivity and detectivity of the Au decorated nanocomposite are analyzed with the increase in incident UV light intensities. The findings are analyzed, and an explanation of the detailed UV photodetection mechanism is outlined in this paper.

Effect of rGO content on enhanced Photo-Fenton degradation of Venlafaxine using rGO encapsulated magnetic hexagonal FeTiO3 nanosheets

In this work, we synthesized magnetic reduced graphene oxide (rGO) encapsulated hexagonal FeTiO3 (FTO@rGO) nanosheets with rGO loading amount of 0, 1, 5 and 10 wt%, with a primary objective of efficiently degrading venlafaxine (VLF) through photo-Fenton processes across a wide pH range of 3–11. The inherent visible-light photocatalytic ability of ilmenite FeTiO3 (FTO) and catalytic activation of H2O2 by Fe sites during the photo-Fenton process were established. Through the strategic integration of rGO, all FTO@rGO catalysts show higher VLF degradation rate than FTO in photo-Fenton evolution experiments and the FTO@rGO catalysts with rGO loading amount of 5 wt% presents the highest VLF degradation rate (100 % VLF degradation at 90 min), which attributed to the accelerated migration of photo-generated electrons and the efficient Fe2+/Fe3+ cycle. Furthermore, the encapsulation of rGO significantly mitigated Fe leaching throughout the reaction pH range, directing H2O2 activation to occur at the FTO@rGO interface instead of in solution. Through a comprehensive analysis, we identified 47 intermediate products of VLF and deduced the degradation pathway based on 12 representative intermediates. The degradation process was primarily driven by hydroxyl radicals as the dominant reactive oxygen species, complemented by the contribution of superoxide radicals, photogenerated electrons, and holes during the FTO@rGO-catalyzed photo-Fenton process. This study not only expands the application of ilmenite in the realm of advanced oxidation processes (AOPs) but also provides valuable insights for the future exploration and development of metal oxide/carbonaceous heterostructure catalysts.

Controlling the Formation of Electroactive Graphene-Based Cementitious Composites: Towards Structural Health Monitoring of Civil Structures.

The development of composites combining multiple components each one imparting a specific function to the ensemble is highly sought after for disruptive applications in chemistry and materials science, with a particular importance for the realization of smart structures. Here, we report on the development of an unprecedented multifunctional cementitious composite incorporating reduced graphene oxide (rGO). By design, this material features significantly enhanced electrical properties while retaining the excellent cement's hydration and microstructure. The multiscale investigation on the chemical and physical properties of the dispersion made it possible to establish an efficient preparation protocol for rGO aqueous dispersion as well as rGO-based cementitious composites using a commercial poly(carboxylate ether)-based superplasticizer. The conduction mechanisms within the matrix of rGO containing mortars were unraveled by electrochemical impedance spectroscopy revealing conductive paths originating from bulk cement matrix and rGO nanosheets in composites with rGO loadings as low as 0.075 wt. %. For this rGO loading, we observed the reduction of the resistivity of bulk cement mortar layers from 18.3 MΩ cm to 2.8 MΩ cm. Moreover, the addition of 0.2 wt. % of rGO resulted in the formation of rGO conductive paths with the resistivity of 51.1 kΩ cm. These findings represent a major step forward towards the practical application of graphene-based materials in structural health monitoring of concrete structures.

Study on the Influence of the Reduced Graphene Oxide Coating on the Hydrophobicity of PU Sponge for Oil Recovery

In order to produce a hydrophobic material for oil removal from surface waters, in this study, the reduced graphene oxide coated PU sponges (rGO@PU) were prepared by ultrasonication of PU sponges with suspension of rGO in ethanol. The chemical structure of the rGO coatings was investigated by X-ray diffraction and FT-IR spectroscopy methods. The surface morphology of the obtained materials was also examined by SEM. The influence of the rGO loadings and the number of coatings on the hydrophobicity of the materials was investigated. The testing on the surface hydrophobicity indicated that the water drops were remained on the surface of rGO@PU for 4.5 - 5 hours. The results indicated that the best hydrophobic sponge was obtained at the rGO loading of 3 mg/mL and after three times of coatings. The water contact angle (WCA) of the optimal rGO@PU was up to 119°. The kerosene oil absorption capacity of the rGO@PU in 5 minutes is 32.34 g/g. Besides, the oil-water separation ability of the material was also investigated by passing the kerosene-water mixture through a filter funnel containing the synthesized porous material rGO@PU. The result indicated that the separation efficiency of the material was 85%. The recyling test was conducted by squeezing the saturated absorbed sponges and applying the desorbed sponges for the next cycle tests. After 10 times of recycling, the amounts of kerosene absorption on the rGO@PU were maintained from 4.39 - 5.33 g, implying the excellent recyclability of the material.

Preparation and Characterization of Chitosan/Reduced Graphene Oxide Film as a Sensing Material

Sensing materials are crucial in a wide range of fields, including environmental monitoring, healthcare, security, and industrial applications. By leveraging their specific properties, sensing materials enable the development of innovative sensing devices and systems for improved detection, monitoring, and control of various parameters in our environment. This study aimed to prepare the chitosan/reduced graphene oxide film as sensing materials using a simple casting method. The reduced graphene oxide (rGO) was mixed with chitosan (CS), consisting of a concentration ratio of 200, 250, 300, 350, and 400 ppm. Three characterizations were used to describe the formed CS/rGO films, namely, Fourier transform infrared (FTIR), X-ray diffraction (XRD), and cyclic voltammetry (CV). FTIR and XRD analysis results were successfully performed, which showed that the process of loading of rGO and the film fabrication occurred in the physical interaction. The CV test also showed that the CS/rGO modified electrode has high sensitivity in PBH pH 7 and can be applied as a sensing material.

Stabilization efficiency of graphene in γ-irradiated styrene-isoprene-styrene copolymer

The stabilization efficiency of reduced graphene oxide (rGO) on the γ-irradiated styrene-isoprene-styrene copolymer (SIS) matrix is studied by chemiluminescence. The relevant protection effects of polymer against oxidation are obtained, when the inorganic phase is present in low concentrations (1, 2 and 3 wt%). The values of the characteristic kinetic parameters of degradation, namely oxidation induction time (OIT) and onset oxidation temperature(OOT) keep their figures in respect with pristine polymer. The γ-exposure of modified SIS probes to various doses up to 100 kGy demonstrates the appropriate ability of rGO to delay thermal and radiochemical oxidation. Because the oxidation strength increases as the rGO loading is greater, these stabilization formulations may be recommended as the appliable versions in the manufacture of long life polymer products. The coupling rGO with rosemary extract for the extension of polymer durability proves the favorable association between the two stabilization mechanisms: the interlayer scavenging shown by rGO and the proton substitution operated by the polyphenolic compounds existing in rosemary extract.

Photocatalysis-Fenton mechanism of rGO-enhanced Fe-doped carbon nitride with boosted degradation performance towards rhodamine B

A photo-Fenton catalyst Fe‑carbon nitride (g-C3N4)/reduced graphene oxide (rGO) (labeled as FNGO) was prepared via two-step calcination thermal polymerization. rGO as a carrier of Fe-g-C3N4 accelerated the charge transfer and improved the reduction of Fe (III) as compared those of the binary Fe-g-C3N4 catalyst. The FNGO catalyst maintained a high surface area of 264.7 m2/g and its charge transfer rate was 2.77 times higher than Fe-g-C3N4. The decreasing transient photocurrent and increasing electrode resistance of FNGO, Fe-g-C3N4 and g-C3N4 confirm the positive synergistic effect of FeN coordination and rGO in charge transfer. Under the synergistic of visible light irradiation and H2O2, the excellent degradation performance of FNGO towards rhodamine B was achieved (95.3 % removal) at Fe-doping content of 10 wt%, rGO loading content of 0.5 % and H2O2 addition of 1.5 mM. Hydroxyl radicals played a dominant role in the photocatalysis-Fenton system, which was related to the coordination of FeN, the carrier off-domain of rGO, and the Fe (III)/Fe (II) cycle promoted by photogenerated electron and superoxide radicals. The FNGO had a high stability, a wide pH adaptation (3– 11) and a low Fe-leaching. This novel ternary light-driven photo-Fenton catalyst of FNGO enabled efficient decontamination during advanced treatment of wastewater.

Preparation of Biodegradable Reduced Graphene Oxide/Agar Composites by In Situ Reduction of Graphene Oxide

Plastics are ubiquitous in our daily life. However, the use of petrochemical-based plastic as packaging materials causes the depletion of non-renewable resources, thereby leading to an increase in oil prices and economic crises. Moreover, these petrochemical plastics raise the issue of environmental pollution due to their non-biodegradability. Owing to this, there is a need to develop an alternative biodegradable and eco-friendly packing material. Agar, which is extracted from seaweeds, is one of the abundantly available polymers. However, moderate tensile strength and thermal stability restrict its application. As a step forward, agar/reduced graphene oxide (RGO) composites were prepared by in situ reduction of GO in the polymer matrix. The tensile strength of the composite was found to increase by 55% at 2% RGO loading. The electrical conductivity and thermal properties of the composite were also improved. The presence of conductivity suggested that apart from packaging, agar/RGO composites can also have potential applications as capacitor plates creating a supercapacitor and as electric field-induced wound healing material.

Photocatalytic degradation of organic pollutants and inactivation of pathogens under visible light via SnO2/rGO composites

The domains of environmental cleanup and pathogen inactivation are particularly interesting in nanocomposites (NCs) due to their exceptional physicochemical properties. Tin oxide/reduced graphene oxide nanocomposites (SnO2/rGO NCs) have potential uses in the biological and environmental fields, but little is known about them. This study aimed to investigate the photocatalytic activity and antibacterial efficiency of the nanocomposites. The co-precipitation technique was used to prepare all the samples. XRD, SEM, EDS, TEM, and XPS analyses were employed to characterize the physicochemical properties of SnO2/rGO NCs for structural analysis. The rGO loading sample resulted in a decrease in the crystallite size of SnO2 nanoparticles. TEM and SEM images demonstrate the firm adherence of SnO2 nanoparticles to the rGO sheets. The chemical state and elemental composition of the nanocomposites were validated by the XPS and EDS data. Additionally, the visible-light active photocatalytic and antibacterial capabilities of the synthesized nanocomposites were assessed for the degradation of Orange II and methylene blue, as well as the suppression of the growth of S. aureus and E. coli. As a result, the synthesized SnO2/rGO NCs are improved photocatalysts and antibacterial agents, expanding their potential in the fields of environmental remediation and water disinfection.

Recycled polystyrene/polyvinylpyrrolidone/reduced graphene oxide nanocomposites for optoelectronic devices

Polymer nanocomposites based on recycled polystyrene (PS) and polyvinylpyrrolidone (PVP) with various reduced graphene oxide (rGO) loadings were prepared through a facile casting technique for enhancing the electrical conductivity of the insulator waste polystyrene to be applicable in electronic devices. The prepared nanocomposites were investigated by different techniques. FTIR analysis shows a reduction and shift of the main vibrational peaks of the blend, which confirms the introduction of (rGO) to the polymeric matrix, while XRD diffractograms provide complementary evidence for the transformation of graphene oxide into (rGO). The SEM image of the fractured edge of the sample points to a homogenous distribution of the PVP inside the major phase of the PS matrix. Moreover, the TEM image shows graphene oxide nanoparticles appearing in the form of dark lamellar structures with some light dots on a gray background, representing the polymeric domain. Besides, the TGA shows the existence of (rGO) led to some shifts in the PS and PVP onset decomposition temperatures when compared to the reference blend sample. Besides, the conductivity and dielectric properties of the prepared nanocomposites were characterized over a wide frequency range. Introducing (rGO) considerably enhanced their dielectric constant and ionic conductivity. The conductivity of these nanocomposites ranged from 10−11 to 10−6 S/m. The dielectric constant and dielectric loss of these composites were tested through frequencies, 0.1 Hz - 1 MHz, at 30 °C. The obtained values of the dielectric constant, loss tangent, and DC conductivity (σdc) suggested that the prepared nanocomposites could be used in various technological sectors such as energy storage, electronics, anti-static, and electro-static dissipation applications.

Investigations on structural, optical and electrical properties of microwave-assisted rGO:ZnO nanocomposite thin films

The reduced graphene oxide:Zinc oxide (rGO:ZnO) nanocomposite films were fabricated by an optimized wet-chemical sol–gel derived spin-coating method. A simple, fast and effective microwave-assisted approach was adopted for the reduction of the graphene oxide. The influence of rGO on the microstructural and optoelectronic properties of ZnO was studied by varying the weight ratios of rGO. The results showed significant changes in the microstructural and optoelectronic properties of the rGO:ZnO composite films. X-ray diffraction analysis confirmed the polycrystallinity of the composite films with a preferential growth orientation of the crystallites along (002) plane. Good optical transparency in the visible wavelength region was observed in all the composite films. As the weight percentage of rGO increased from 0% to 20%, the red shift of the absorption edge was noticed, indicating the weak Burstein-Moss effect. The optical bandgap of ZnO reduces as the amount of rGO increases, resulting in the reduction of transmittance in the composite thin films. The sheet resistance and therefore the resistivity of the composite films decreases with the loading of rGO into ZnO matrix. The lowest values of sheet resistance and resistivity, and the highest Figure of Merit have been recorded for 10% rGO:ZnO composite film. The obtained results illustrate that the 10% rGO:ZnO composite film could be a potential candidate for electrode applications.

Enhancing thermal stability of polycarbonate films with one‐sided coating of graphene oxide

AbstractIn this study, polycarbonate (PC) films were coated with a thin layer of graphene oxide (GO) or its reduced form (rGO) via vacuum filtration. The effects of the coating on PC were studied by means of modulated differential scanning calorimetry (mDSC), thermogravimetric analysis (TGA), and scanning electron microscopy. As shown by mDSC, there was no significant change in glass transition temperature (Tg), indicating little molecular interaction between the PC and the coating. In addition, GO and rGO showed poorer thermal stability than the neat PC, which is consistent with the literature. Despite these findings, both GO‐ and rGO‐coated PC films exhibited significantly higher onset thermal degradation temperatures than the neat PC. Moreover, when the rGO loading was below a certain level, the coated PC films demonstrated a comprehensive enhancement in thermal stability over the entire temperature range of TGA measurement. Such enhancement could be observed even at very low rGO loadings when the surface of the PC film was partially coated.