Graphene Oxide Sheets Research Articles

Non-rigid metal–oxygen bonding empowered nitrate reduction on ruthenium catalysts

Electrocatalytic nitrate reduction (NitRR) offers exciting potential for mass production of ammonia (NH3) from renewables. However, the rigidity of metal−ligand bonds in most electrocatalysts renders them unable to survive the structural transformations required for NitRR. Herein, we establish a type of non-rigid metal−oxygen bonds by employing graphene oxide (GO) sheets as a 'micron-scale' ligand for transition metals (TM). Because of being confined to the interfaces between GO and TM, the oxygenated groups in GO can associate with and dissociate from the TM in response to reaction dynamics. As a proof-of-concept demonstration, an electrocatalyst was developed by dispersing nanoscale ruthenium (Ru) on graphene oxide (GO) and utilizing two-dimensional MXene to compensate for the low electrical conductivity of GO. This electrocatalyst exhibits a maximum NH3 yield of over 5 mg cm−2 h−1, with almost 100 % current-to-NH3 efficiency, far outperforming the performance of most reported Ru-based materials. What's even more remarkable is the achievement of a record-breaking performance: a 200-hour stable electrolysis with a NH3 yield of 40.2 mg cm−2 h−1, using a membrane electrode reactor. Our experimental and theoretical investigations further reveal the non-rigidity of the Ru–O bonds and how they self-regulate to adapt to diverse intermediates involved in NitRR. This work provides an approach to fabricate a high-performance electrocatalyst featuring reversible and non-rigid metal−oxygen bonds, opening new possibilities for practical nitrate electrolysis.

Synthesis and characterization of zinc ferrite nanoparticles@GO for the photocatalytic degradation of Methylene Blue dye under visible light

Due to rising environmental pollution, there has been a growing focus on photo degradation catalysts for pollution removal. Under visible light irradiation, methylene blue dye (MB) photocatalytic degradation has been studied using Zinc ferrite nanoparticles (ZnFe2O4 NPs) and Zinc ferrite nanoparticles/graphene oxide (ZnFe2O4/GO). Methylene blue dye is a carcinogenic pollutant that poses risks to both humans and marine life. The synthesis of ZnFe2O4/GO was achieved by the biotemplating method. Synthesized nanoparticles were loaded on graphene oxide (GO) in different ratios (Zn1:GO1, Zn1:GO3, and Zn1:GO5). Nanocomposite characterization was done utilizing Raman Spectroscopy analysis, FT–IR, XRD, BET, FE-SEM–EDX, XPS, and TEM. The confirmation of the cubic spinel structure of ZnFe2O4 NPs has been validated uniformly distributed on the surface of the GO sheets. The vigorous interaction between ZnFe2O4 NPs and graphene sheets facilitates rapid electron mobility, enhancing electron separation and holes in photocatalytic applications. The aforementioned parameters are crucial in MB’s photocatalytic degradation performance. Photocatalytic degradation processes depend on pH solution, initial dye concentration, and catalyst dosage. The outcomes demonstrated that augmenting the proportion of graphene oxide amplified MB photo degradation. Under the optimum conditions of 1 g/L dose, pH 8, 10 mg/L initial dye concentration, and 180-min irradiation time, the degradation ratio increased to 51.17 %, 59.70 %, 89.49 %, and 97.38 % using ZnFe2O4, Zn1:GO1, Zn1:GO3, and Zn1:GO5, respectively. Based on the photo degradation process, GO exhibited superior photocatalytic performance at the highest concentration. The kinetics data showed that the photo degradation reaction adheres to the pseudo-second-order. The study indicated that the eco-friendly, non-toxic photocatalyst ZnFe2O4/GO can be used as an effective potential substance for water treatment as well as the elimination of hazardous organic dyes from aqueous solutions.

Flower-like SnO2 nanorod aggregates modified with Co3O4 nanoparticles grown on reduced graphene oxide(rGO) sheets for xylene sensing

In this paper, the ternary composite of flower-like SnO2 nanorod aggregates modified with Co3O4 nanoparticles grown on rGO sheets were synthesized by a two-step process of water heating and water bath, and characterized by SEM, TEM, XRD, EDS, and XPS. The gas-sensitive performance test results revealed that the 15-rGO/SnO2/Co3O4 sensor exhibited a higher response value (I0/Ia=24.46) to 100 ppm xylene at the optimal working temperature of 175℃. In addition, the sensor could detect 10 ppb xylene, with a low detection limit. The gas-sensitive properties of 15-rGO/SnO2/Co3O4 were significantly improved due to the large specific surface area of rGO flakes and SnO2 slender nanorods, the catalytic action of p-type semiconductor Co3O4 and the existence of p-n-p double heterojunction. Due to the special nanostructure and synergistic effect of SnO2, rGO and Co3O4, the 15-rGO/SnO2/Co3O4 sensor enabled the efficient and selective detection of xylene.

Production and characterizations of silver-doped copper ferrite anchored in RGO surface

The rapid advancements in nanotechnology have spurred the search for more efficient materials across various advanced applications. To this end, this study aimed to synthesize and investigate the structural properties of copper ferrite and mixed copper-silver ferrite anchored onto reduced graphene oxide (rGO) sheets. Samples were synthesized via the hydrothermal method at four different temperature ranges for 6 h at pH 11. The systems were analyzed using Raman spectroscopy, X-ray diffraction (XRD), and Scanning Electron Microscopy (SEM). XRD analysis revealed changes in the structural parameters of the ferrite, the presence of Fe2O3 and Ag, and confirmed the anchorage of submicron particles onto rGO, along with diversified morphologies. Both Raman spectroscopy and XRD confirmed the reduction of graphene oxide (GO) to rGO.

Controllable tribological behavior of PNIPAM-graphene oxide nanocomposites at titanium alloy interface

In order to improve antiwear properties of the cutting tool for titanium alloy, the temperature-sensitive poly(N-isopropylacrylamide) (PNIPAM)-graphene oxide (GO) nanocomposites were developed in this work. The tribological properties of the titanium alloy/cemented carbide contact lubricated with the PNIPAM-GO nanocomposites were investigated. The results show that the PNIPAM-GO nanocomposites have stable dispersive and controllable lubricating performance. The wear of the titanium alloy decreased and the adhesive behavior was improved with the increase of GO in the nanocomposites. The tribological performances are attributed to both the controllable release of GO sheets from the nanocomposites and the formation of a protective tribofilm. A mechanical mixing submechanism counts for the decrease of friction and wear of titanium alloy/cemented carbide contact lubricated by the nanocomposites.

Interactions of graphene oxide with the microbial community of biologically active filters from a water treatment plant

With widespread occurrence and increasing concern of emerging contaminants (CECs) in source water, biologically active filters (BAF) have been gaining acceptance in water treatment. Both BAFs and graphene oxide (GO) have been shown to be effective in treating CECs. However, studies to date have not addressed interactions between GO and microbial communities in water treatment processes such as BAFs. Therefore, in the present study, we investigated the effect of GO on the properties and microbial growth rate in a BAF system. Synthesized GO was characterized with a number of tools, including scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDX), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and Raman spectrometry. GO exhibited the characteristic surface functional groups (i.e., C-OH, C=O, C-O-C, and COOH), crystalline structure, and sheet-like morphology. To address the potential toxicity of GO on the microbial community, reactive oxygen species (ROS) generation was measured using nitro blue tetrazolium (NBT) assay. Results revealed that during the exponential growth phase, ROS generation was not observed in the presence of GO compared to the control batch. In fact, the adenosine triphosphate (ATP) concentrations increased in the presence of GO (25 μg/L - 1000 μg/L) compared to the control without GO. The growth rate in systems with GO exceeded the control by 20 % to 46 %. SEM images showed that GO sheets can form an effective scaffold to promote bacterial adhesion, proliferation, and biofilm formation, demonstrating its biocompatibility. Next-generation sequencing (Illumina MiSeq) was used to characterize the BAF microbial community, and high-throughput sequencing analysis confirmed the greater richness and more diverse microbial communities compared to systems without GO. This study is the first to report the effect of GO on the microbial community of BAF from a water treatment plant, which provides new insights into the potential of utilizing a bio-optimized BAF for advanced and sustainable water treatment or reuse strategies.

Fluorescence immunoassay using triangular carbon dots for detection of the cardiac marker Troponin T in acute myocardial infarction

A cardiac immunosensor was developed to detect heart attacks (myocardial infarctions) at an early stage. This technique, utilizing carboxylic functionalized triangular carbon dots (caf-TCDs) combined with an antibody anti-cardiac Troponin T (anti-cTnT), proved to be a quick and sensitive method for detecting cardiac troponin T (cTnT) in both buffer solutions and biological fluids such as serum. The antibody for cardiac Troponin T (cTnT) was chemically linked to amphiphilic caf-TCDs using a carbodiimide coupling reaction. Exfoliated graphene oxide (GO) sheets effectively bind to anti-cTnT labeled caf-TCDs on their surface, resulting in a non-radiative energy transfer process where the fluorescence is suppressed. This interaction between caf-TCDs and GO follows a nonlinear and increasing Stern-Volmer relationship, indicating a combination of static and dynamic quenching. When antigen (cTnT) is present, the interaction between antibodies (anti-cTnT) and the cTnT molecules hinders the energy transfer process. This interaction also affects the positioning of the nano-couple and causes the detachment of CDs from the GO surface. As a result, the energy transfer process is impeded, leading to the restoration of fluorescence intensity. The sensor exhibits high specificity and low sensitivity to non-specific antigens. It shows a linear reaction to cTnT in the range of 0.05–50 ng mL-1, with a detection limit of 0.046 ng mL-1. Therefore, the anti-cTnT-caf-TCD/GO sensor offers a potential platform for detecting cTnT with increased sensitivity.

The Rheological and Structural Properties of Aqueous Graphene Oxide Dispersions: Concentration and pH Dependence.

A modified Hummer's method was used to synthesize aqueous dispersions of graphene oxide (GO). The morphology, chemical structure, and exfoliation state of GO were analyzed by combining scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD). The structural and rheological properties of the GO dispersions were studied as a function of GO concentration and pH. Increasing the concentration of GO revealed shorter interparticle distances between GO sheets. This induced a transition from fluid to nematic gel-like structures, as observed by polarized optical microscopy (POM). The Herschel-Bulkley model was used to fit the shear thinning curves and to demonstrate the viscoelastic behavior. Both the yield stress and viscoelastic moduli in the linear viscoelastic regime increased. As pH increases, the color of the aqueous GO dispersions becomes darker, the negative values of the zeta potential increase, the distances between the GO sheets decrease as observed by a slight shift of the correlation peak toward higher values of the scattering vector modulus in small-angle X-ray scattering (SAXS), and the rheological properties (yield stress and viscoelastic moduli in the linear viscoelastic region) decrease. These results can be explained by a change in the morphology of GO related to their hydrophilicity. This work presents relationships between rheological and structural properties of GO sheet dispersions, with particular emphasis on the effects of concentration and pH.

Controllable synthesis of carbon supported cobalt monoxide anode and high-voltage lithium cobalt oxide cathode with enhanced lithium-ion storage

Natural macromolecule amylose (AM) is employed to deoxygenate few-layered graphene oxide (GO) and modulate the surface interaction between GO sheets and Co2+ ions under mild hydrothermal conditions. The obtained Co2+ ions and AM molecule jointly decorated reduced graphene oxide (Co-AM/RGO) sample is further utilized to synthesize both anode and cathode materials with controlled microstructures. To synthesize anode material, the Co-AM/RGO can be directly converted to a hierarchical AM pyrolyzed carbon and RGO supported cobalt monoxide nanocomposite (CoO@AMC/RGO) after a simple inert gas protected thermal treatment. To synthesize cathode material, a carbon coated nano-sized lithium cobalt oxide sample (LiCoO2/C, LCO/C) can be obtained after a solid-state reaction in air by mixing lithium salt with the Co-AM/RGO. The CoO and LCO nanocrystals with significantly controlled sizes are well dispersed in the carbon matrices. The CoO@AMC/RGO anode shows a high reversible capacity of 785.25 mAh·g−1 after 500 cycles at 200 mA·g−1 and 608.25 mAh·g−1 after 700 cycles at 1000 mA·g−1, while the LCO/C cathode delivers a superior reversible capacity of 140.91 mAh·g−1 after 1000 cycles at 1000 mA·g−1 with a high cut-off voltage of 4.6 V. This work provides a new perspective for controllable engineering of electrode materials with enhanced lithium-ion storage performances.

Fe2O3 decorated reduced graphene oxide sheets for enhanced sensing applications for dopamine

Fe2O3 decorated reduced graphene oxide sheets for enhanced sensing applications for dopamine

Evaluating the Impact of Sonication Process on Graphene Oxide Structural Properties

Graphene oxide (GO) is one of the members of carbon-based nanomaterials and can be featured as graphene structure decorated with various oxygenated functional groups. Recently, various methods have been found for producing carbon-based nanomaterials with enhanced efficiency in several applications. The chemical process involves oxidizing graphite to GO using a powerful oxidizing chemical. Hummers method is one of the most known and versatile method for the production of GO nanomaterials because of its ease of application, parameter controllability and high yield. This process enables graphite oxidation and exfoliation into single- or multi-layered GO sheets. Exfoliation, the separation of graphene or graphitic layers, is a critical process in GO synthesis. Since exfoliation separates multilayered graphite oxide flakes or particles, it forms single layer GO by forcing oxidizing agents or solvent molecules between layers. The sonication process can exfoliate the oxidized layers, resulting in the formation of GO structure when the exfoliated layers consist of only one or a few layers of carbon atoms. Therefore, sonication procedure is among the key parameters of Hummers method that influences the characteristics of GO-based nanomaterials. In this study, the impact of sonication duration time and power parameters on morphological and structural characteristics of GO development was examined. For this purpose, characterization studies were performed by using Scanning electron microscope (SEM), X-ray powder diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), UV-Vis spectroscopy and Raman spectroscopy analysis. The findings revealed that the increase in sonication power and time led to an increase in defects in the resulting GO structure.

Exploring Reduced Graphene Oxide Sheets Stabilized by Cu(II) and Cu(I) Cations in Ethanol

In this study, ultrasound treatment was used to exfoliate commercially available graphite flakes into reduced graphene oxide (rGO) dispersed in ethanol. After centrifugation, solid copper chloride trihydrate was added, resulting in a green liquor containing Cu(II), Cu(I), and rGO. These liquors exhibited good and rapid photocatalytic activity in the degradation of eosin and bromophenol blue dyes (elimination in a few seconds) under visible-light irradiation. UV–visible spectroscopy confirmed the presence of rGO and Cu species. The size and morphology of the rGO sheets were investigated by several methods (SAXS, wide-angle XRD, SEM, and TEM). Negative UV peaks indicated light emission, which was independently verified by fluorescence. Intense plasmon peaks, with absorbances greater than 10, were observed after adding copper chloride salt. These plasmons were eliminated by a high dilution before the described catalytic tests were performed.

High-performance humidity sensors based on reduced graphene oxide sheets decorated with cobalt and iron doped ZnO nanorods

Humidity sensors based on doped zinc oxide (ZnO) / reduced graphene oxide (rGO) composites have shown potential since the doped ZnO/rGO material is sensitive to changes in humidity. Here, the present work report of one-step hydrothermal synthesis of ZnO/rGO and doped ZnO/rGO nanocomposites where ZnO has been doped with cobalt and iron at concentrations of 2 %. X-ray diffraction validates the substitution of transition metal cations in the ZnO lattice. Scanning electron microscopy depicts a graphene-layered structure with intact ZnO rods. Humidity sensors based on Fe doped ZnO/rGO composite showed response and recovery periods of 27 s and 24 s, respectively, in the range of 11–97 % relative humidity. The composite has the sensitivity of 2.2 kΩ at 100 Hz which is the highest as compared to ZnO/rGO and Co doped ZnO/rGO. Because of the greatest sensitivity and quick reaction and recovery timer, Fe doped ZnO/rGO composites appear to be ideal for use as humidity sensors.

Design of interconnected graphene loaded thermoplastic elastomeric blend composite films for minimizing electromagnetic radiation and efficient heat management

AbstractIn this work, electrically conductive thermoplastic elastomeric blend composite films based on polystyrene (PS)/ethylene‐co‐methyl acrylate (EMA) filled with functionalized graphene were developed via the solution mixing technique. Morphological analysis revealed that selective localization of amine‐functionalized reduced graphene oxide (G‐ODA) sheets in the EMA phase of co‐continuous binary blend formed a well‐connected dense conductive pathway by graphene sheets ultimately facilitating the double percolation phenomenon. The electrical percolation threshold was achieved at ~2 wt% of G‐ODA loading which was much lower than that for both single polymer composites. An electrical conductivity of 0.9 S/cm was obtained for blend composite film with 10 wt% of graphene concentration whereas for the same filler loading, PS and EMA composites exhibited electrical conductivity of 1.9 × 10−1 and 2.3 × 10−1 S/cm, respectively. The obtained thermal conductivity of the blend composite with 10 wt% of G‐ODA loading was 0.95 W/m K with 400% enhancement compared to the neat blend system. The same composite exhibited increased real and imaginary permittivity of 92 and 83, respectively. The electrical percolation threshold is well‐correlated with the percolation concentration found from storage modulus and thermal conductivity data. The fabricated PS/EMA blend composite film exhibited absorption‐dominant electromagnetic interference SE of −25 and − 35 dB in X‐band frequency (8.2–12.4 GHz) for 10 wt% of graphene loading with a sample thickness of 0.5 and 1 mm, respectively.

Holey Sheets Enhance the Packing and Osmotic Energy Harvesting of Graphene Oxide Membranes.

Layered membranes assembled from two-dimensional (2D) building blocks such as graphene oxide (GO) are of significant interest in desalination and osmotic power generation because of their ability to selectively transport ions through interconnected 2D nanochannels between stacked layers. However, architectural defects in the final assembled membranes (e.g., wrinkles, voids, and folded layers), which are hard to avoid due to mechanical compliant issues of the sheets during the membrane assembly, disrupt the ionic channel pathways and degrade the stacking geometry of the sheets. This leads to degraded ionic transport performance and the overall structural integrity. In this study, we demonstrate that introducing in-plane nanopores on GO sheets is an effective way to suppress the formation of such architectural imperfections, leading to a more homogeneous membrane. Stacking of porous GO sheets becomes significantly more compact, as the presence of nanopores makes the sheets mechanically softer and more compliant. The resulting membranes exhibit ideal lamellar microstructures with well-aligned and uniform nanochannel pathways. The well-defined nanochannels afford excellent ionic conductivity with an effective transport pathway, resulting in fast, selective ion transport. When applied as a nanofluidic membrane in an osmotic power generation system, the holey GO membrane exhibits higher osmotic power density (13.15 W m-2) and conversion efficiency (46.6%) than the pristine GO membrane under a KCl concentration gradient of 1000-fold.

Thin polyamide layer cross-linked graphene-oxide based ceramic membranes for efficient separation of the surfactant stabilized oil-in-water emulsions

Two-dimensional (2D) graphene oxide (GO) membranes (GOM) have great potential in separation applications. However, GOMs face two distinct challenges: low flux arising from their tight stacking and instability arising from re-exfoliation of GO sheets in solution. To address these challenges, herein, we report the functionalization of basal planes of GO layers with 2-[2-(3-Trimethoxysilylpropylamino)ethylamino]ethylamine (TSE), followed by transforming them into membranes through a two-step process. In the first step, the functionalized GO sheets were assembled onto the porous ceramic support. At this stage, the interlayer distance between GO sheets was modulated via TSE’s long hydrocarbon chain. Afterward, the free amines of TSE on functionalized GO membranes (fGOM) surface were cross-linked with trimesoyl chloride (TMC) to prepare a hydrophilic thin-layer on top of fGOM (TL-fGOM), further enhancing their stability. Further, TL-fGOMs were tested for oil-in-water-emulsion separation. The increased interlayer distance and the increased surface hydrophilic nature of TL-fGOM offered ultra-high water permeance, 4860 % higher compared to the non-functionalized GOM. Moreover, the separation efficiency of TL-fGOM improved from 37 % of that of ceramic membranes to 99.5 %. Additionally, they showed excellent anti-fouling properties. After exposing the membranes to 500 ppm emulsion for 10 hours in batches, the flux recovery ratio exceeded 90 %. The TL-fGOM in our work demonstrated outstanding performance in purifying oily emulsions containing diesel/toluene/heptane-in-water. All these results revealed that the appropriate functionalization of graphene oxide could assist in forming a thin layer of graphene oxide on the support membranes, offering high separation efficiency and fouling resistance. This approach can be extended further to utilize the graphene oxide membranes for practical applications.

3D printed hetero-layered composite scaffold with engineered superficial zone promotes osteogenic differentiation of pre-osteoblast MC3T3-E1 cells

In bone tissue engineering, a new design of composite scaffold with various compositions by incorporating both natural and synthetic cues via dual nozzle 3D printing technique could efficiently accelerate the cell differentiation to osteogenic lineage. Based on the hypothesis that a biomimetic scaffold per se can supply the vital cues to provoke bone formation, 3D printed poly(ε-caprolactone) (PCL) scaffold loaded with synthetic hydroxyapatite (HAs) decorated on graphene oxide (GO) sheets (GO@HAs), was developed. To further improve its osteogenic potential, the upper and lower layer/s of scaffolds were 3D printed using another ink containing PCL and naturally allograft HA (HAa). The FE-SEM images of the 3D printed scaffolds revealed a highly regular architecture, demonstrating the successful printability of the developed materials. The compressive mechanical test confirmed the drastic role of GO@HAs on the enhancement of Young's modulus and mechanical strength of the PCL scaffold. Moreover, existence of HAa on the upper and lower sections of scaffold interestingly improved the cellular behavior of the 3D printed scaffold without having an adverse effect on mechanical features. The experimental results indicated that such engineered scaffold significantly facilitated the cell attachment and evoked higher levels of pre-osteoblast MC3T3-E1 differentiation than PCL/GO@HAs scaffold as demonstrated by alizarin red staining, ALP activity and osteo-related gene expression. Taken together, these results indicate that such fascinating scaffold comprising both mechanical and biological cues has a high potency for inducing bone repair and also open new avenues for future advancements in the realm of bone tissue engineering exploration.

Elevating capacitive features of hydrothermally produced CeVS3 utilizing rGO for supercapacitor applications

This work presents the fabrication of a novel CeVS3/rGO nanocomposite using an easy hydrothermal route for supercapacitor applications. Physical studies revealed that CeVS3 showed flakes-like morphology, which is successfully decorated on reduced graphene oxide (rGO) sheets in nanocomposite. The electrochemical studies exhibited that fabricated CeVS3/rGO showed improved capacitive behavior with notable specific capacitance (Cs) of 1516 F/g at 1 A/g current density (jd) as well as excellent rate capability due to combined effect of CeVS3 nanoflakes and rGO sheets. Nanocomposite also demonstrated a lower resistance of 0.21 Ω than pure material, which have a charge transfer resistance (Rct) of 0.48 Ω. Furthermore, a two-electrode symmetric study was carried out in KOH solution (2.0 M), demonstrating a specific energy (SE) of 18.73 Wh/kg and specific power (SP) of 264.5 W/kg with remarkable cyclic stability after 5000 cycles. These findings demonstrated that innovative CeVS3/rGO can be utilized in next-generation supercapacitor applications.

Structural, microstructural and optical characteristics of rGO-ZnO nanocomposites via hydrothermal approach

This paper describes the production and characterizations of reduced graphene oxide-zinc oxide (rGO-ZnO) nanocomposites fabricated via hydrothermal approach. Firstly, rGO powder was produced via modified Hummers' method and ZnO nanoparticles using chemical co-precipitation. The nanocomposites structural, microstructural and optical characteristics were determined using X-ray diffraction (XRD), infrared spectroscopy (FTIR), Raman spectroscopy and Ultraviolet–visible (UV–Vis) spectroscopy. The findings demonstrated the effective synthesis of rGO-ZnO nanocomposites with evenly distributed ZnO nanoparticles on the surface of reduced graphene oxide sheets. rGO-ZnO nanocomposites with different concentrations ratio rGO:ZnO in composition of 10:0. 7.5:2.5, 5:5, 2.5:7.5, and 0:10 (weight percentage) were formed. An average crystallite size (Davg) was observed to be decreasing with an increasing concentration of ZnO in to rGO from ∼13.96 nm to ∼21.36 nm which is supported by Williamson-Hall (W–H) extrapolation. The FTIR spectra showed the functional groups belongs to intrinsic and extrinsic vibrations v1 and v2 at ∼410 cm−1 for rGO and metal‒oxygen (Zn–O) stretching vibrations ∼400 cm−1 to ∼500 cm−1 for rGO-ZnO nanocomposites. On rising ZnO content in the rGO-ZnO nanocomposites, a slight variation in band positions was caused due to the microstructural changes. Raman spectroscopy revealed certain peaks (D, G, for rGO; E2, A1 (TO), LO for ZnO) in various compositions. The research demonstrates how the composition of a material affects its vibrational characteristics, which is crucial for customizing the material for certain applications. The optical energy band gap of rGO-ZnO 75 % was recorded to be ∼4.94 eV, and highest for rGO with 5.44 eV. The optical energy band gap decreased from 5.44 eV to 4.94 eV. This decrease can be attributed to the influence of the smaller crystallite size and fluctuations in microstructural properties caused by the rGO-ZnO nanocomposite. The obtained rGO-ZnO nanocomposites can be utilized for opto-electronic device applications.

RTV/GO-SiO2 anti-corrosion nanocomposite coating

Corrosion stands out as a leading factor contributing to the deterioration of industrial components, particularly in equipment utilized for oil and gas transmission and processing. Room temperature vulcanized silicone rubber (RTV) emerges as a promising solution for corrosion prevention due to its notable features including high hydrophobicity, adhesion, and thermal stability. This study focuses on enhancing anti-corrosion properties by applying coatings of RTV polymer with graphene oxide (GO) sheets (RTV-GO) or GO decorated with silicon oxide (RTV/GO-SiO2) onto X60 steel substrates. The investigation delves into the microstructure of the coating, surface hydrophobicity, adhesion to the substrate, and its efficacy in corrosion protection. Various techniques such as X-ray diffraction (XRD), atomic force microscopy (AFM), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), and Fourier transform infrared spectroscopy (FTIR) were employed to analyze the nanocomposites. Furthermore, corrosion resistance was evaluated through open circuit potential analysis, potentiodynamic polarization, electrochemical impedance spectroscopy, and salt spray testing. Results indicate that incorporating GO and hybrid GO-SiO2 into the RTV polymer matrix not only enhances the interface strength between the coating and steel substrate but also boosts corrosion resistance by up to 10-fold compared to uncoated substrates.