Agglomeration Of Graphene Oxide Research Articles

Intermolecular interactions in graphene and oxidized graphene nanocomposites

The spatial arrangement of graphene (G) or graphene oxide (GO) nanoplate agglomerations will significantly impact the material properties of graphene-based polymer nanocomposites. Therefore, we investigated the stability of G and GO agglomerates without the presence of a polymer network using molecular dynamics (MD) simulations, which was not considered in our previous work (Reil, 2022) [15]; [16]. G and GO nanoplates, often procured in powder forms, display a significant volume difference by visual observation. To this end, MD simulations were performed to model G or GO agglomerations in the powder form, including the effects of varied plate dimensions and localized surface oxidation. G plates on average released 231 kcal/mol upon agglomerating into aligned stacks, closely matching results in the literature. Simulations of GO resulted in agglomerations of clusters of plates rather than aligned stacks, releasing on average 16 % less energy than G. The clustered arrangement of GO plate agglomerates in simulations occupied a volume approximately 7x that of the aligned stack G plates, closely replicating the experimentally determined volume ratio of 10x. This research could yield further insight into the behavior of G and GO when in the presence of various polymer networks, which could be different than in isolation.

Comparative analysis of the synergistic effects of hybrid nanomaterial reinforcement in cementitious Composites: A perspective for pore refinement and thermal resistance

This study aimed to reveal the synergistic effects of graphene oxide (GO)/nanosilica (NS)/functionalized carbon nanotube (FCNT) hybrid nanomaterials on the thermal resistance and pore refinement of cementitious composites. The dispersion states and sizes of the nanomaterials in distilled water and Ca2+-rich solutions were assessed. In addition, the pore characteristics and thermal resistance of the nanomaterial-incorporated cementitious composites were analyzed. In the GO/NS/FCNT hybrid solution, a reinforcing effect of FCNT on the GO plate resulted in high resistance to wrinkling and agglomeration of GO; therefore, the stretched GO plate structure was advantageous for long-term dispersion maintenance, and well-dispersed NS enabled a more active pozzolanic reaction in cement paste. As a result, the triple-hybrid GO/NS/FCNT-reinforced cementitious composites demonstrated improved thermal resistance owing to their high residual strength after heating as well as homogenized pore structures with less elongated pore shapes and lower porosity than control specimens without nanomaterials.

Influence of physico‐mechanical and electrical resistivity performance of high volume fly‐ash cementitious mortar with low carbon

AbstractA graphene oxide (GO) has the potential to improve the strength and hardness of cementitious matrix. The agglomeration of GO in an alkaline medium of cement matrix reduced the reinforcing efficiency. In this study, two types of control samples were fabricated named OPC‐C (OPC control) and HVFA‐C (OPC + 50% FA control) without the addition of GO and four HVFA cementitious mortar samples HVFA‐G1, HVFA‐G2, HVFA‐G3, and HVFA‐G4 were prepared with incorporation of GO 0.005%, 0.010%, 0.020% and 0.040%, respectively. The results revealed that the superplasticizer stabilized GO in cement mortar, significantly improves the compressive (27.12%) and split tensile strength (38.16%) in the HVFA‐G3 mix as compared to HVFA‐C at a curing age of 90 days. The maximum electrical resistivity attained in HVFA‐G4 (83%) mix as compared to OPC‐C at a curing age of 90 days. In addition, microstructural analysis of HVFA cementitious mortar was conducted using a Field Emission‐Scanning Electron Microscope (FE‐SEM), while the crystallization behavior of hydration products ware examined through Powdered X‐Ray Diffraction (PXRD). Furthermore, the chemical bonding between the hydration products was studied using Fourier Transform Infrared Spectroscopy (FT‐IR). Overall, it is concluded that the superplasticizer stabilized GO in HVFA cementitious mortar, helps to achieve better mechanical strength, electrical resistivity performance, and microstructural behavior.

A novel approach for chloride control in sea sand cement composites utilizing graphene oxide

The scarcity of river sand has resulted in the inappropriate use of sea sand in numerous countries, particularly in coastal regions. Without effective desalination techniques and sufficient monitoring, the presence of chloride ions in sea sand leads to rapid reinforcement corrosion and frequent structural failures every year. In this paper, a novel pre-treatment method utilizing graphene oxide (GO) coating on amino-functionalized sea sand (GO-CAFSS), and the effects of GO-CAFSS on suppressing internal chloride leaching and performance of sea sand cement-based composites were investigated. Due to strong covalent bonds between GO and amino-functionalized sea sand, agglomeration of GO in the cement matrix is restrained, which leads to enhanced cement hydration and densified ITZs proved by combined microstructure tests. The chloride leaching test shows that the mass percentage of chloride ions leached from the surface of GO-CAFSS are effectively inhibited, from 0.082% (untreated sea sand) to 0.042%. The chloride binding experiment reveals that the treatment of sea sand cement-based composites with GO-CAFSS can enhance their chloride binding capacity by up to 39.5% after 14 days of exposure to NaCl solution. XRD/TGA test results indicate that GO can enhance the chloride binding capacity by promoting calcium silicate hydrate (C-S-H) and Friedel’s salts (FS) formation, further increasing the physical adsorption and chemical substitution of remaining free chloride ions in the pore solution. It is also found that GO can contribute to the conversion of Ettringite (AFt) into FS with Cl− substituting SO42− to a certain extent, especially with additional intermixed SO42− brought by sea sand. Overall, GO-CAFSS is investigated to be a promising way for making high performance sea sand cement composites with harmful chloride ions effectively controlled.

Macro-Size Regenerated Cellulose Fibre Embedded with Graphene Oxide with Antibacterial Properties.

Macro-size regenerated cellulose fibres (RCFs) with embedded graphene oxide (GO) were fabricated by dissolving cellulose in a pre-cooled sodium hydroxide (NaOH)/urea solution and regenerated in sulphuric acid (H2SO4) coagulant. Initially, GO was found to disperse well in the cellulose solution due to intercalation with the cellulose; however, this cellulose-GO intercalation was disturbed during the regeneration process, causing agglomeration of GO in the RCF mixture. Agglomerated GO was confirmed at a higher GO content under a Dino-Lite microscope. The crystallinity index (CrI) and thermal properties of the RCFs increased with increasing GO loadings, up to 2 wt.%, and reduced thereafter. Cellulose-GO intercalation was observed at lower GO concentrations, which enhanced the crystallinity and thermal properties of the RCF-GO composite. It was shown that the GO exhibited antibacterial properties in the RCF-GO composite, with the highest bacterial inhibition against E. coli and S. aureus.

Graphene oxide microstructure control of electrosprayed thin films.

The graphene oxide (GO) microstructure, in terms of flake distribution, folding, and crumpling, in thin films affects properties such as electrical conductivity and optical transparency after GO reduction. A thin film can be tailored to the user's application if the microstructure resulting from different deposition methods can be controlled. In this work, we compare the microstructures of GO coatings created through electrospray deposition (ESD) with random deposition processes. The comparisons include both MATLAB simulations and a dip coating process. The microstructure of ESD GO thin films can be altered by changing the distance between the nozzle and the substrate. We developed a semi-automatic image analysis script that analyzes scanning electron microscopy images to find effects of GO stacking or agglomeration, without the risk of human bias. A low nozzle to substrate distance creates structures of flat GO flakes, but solvent flooding the samples causes drying patterns. A high nozzle to substrate distance causes folding and crumpling of the GO flakes due to solvent evaporation, resulting in agglomerated GO on the substrate. For our ESD setup, a nozzle to substrate distance of 2-4 mm produced GO coatings with the lowest combined influence of drying effects and GO flake folding or crumpling.

Preparation of well-dispersed graphene oxide-silica nanohybrids/ poly(lactic acid) composites by melt mixing

Graphene oxide has a strong tendency to agglomerate in polymers that are only hydrogen bonded acceptors due to the strong hydrogen bonding and van der Waals forces between its lamellae, which greatly limits its application. In this work, Silica (SiO2) was introduced on the surface of graphene oxide (GO) by hydrolysis of tetraethoxysilane (TEOS). Graphene oxide-silica/polylactic acid (PLA) composites with different grafting ratios were prepared by melt blending. The results by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and X-ray photoelectron spectrometry (XPS) show that the silica is grafted on the GO surface in the form of covalent bonds. Other test results show that regulating the amount of TEOS addition could effectively control the grafting rate. The performance test shows that grafting SiO2 on the GO surface can increase the layer spacing of graphene oxide flakes and thus improve its melt dispersion. It also slows down or improves the performance degradation caused by the severe agglomeration of graphene oxide. At the grafting rate of 45.65%, GO is well exfoliated and well dispersed in PLA in the form of monolayers resulting in a substantial improvement in crystalline properties, mechanical properties, and barrier properties. This work solves the problem of severe agglomeration of GO in polymers that are only hydrogen bond acceptors by modifying GO, and provides guidance for the melt processing of graphene oxide and polymers that are only hydrogen bond acceptors.

Adsorption of Orange G in Liquid Solution by the Amino Functionalized GO

Dye effluent damaged the water environment and human health with its massive discharge. In order to eliminate dye from the water environment, a variety of adsorbents were used to investigate dye removal. Graphene oxide (GO) attracted extensive attention due to its excellent surface property in the degradation of dye wastewater. Modified GO with multifunctional groups helped to improve adsorption performance. 3-Aminopropyltriethoxysilane modified GO (AS-GO) was fabricated for the removal of Orange G (OG) in this study. The results showed that AS-GO had an excellent adsorption ability of OG. During the reaction process, the maximum adsorptive capacity of OG was up to 576.6 mg/g at T = 313 K and pH = 3 with the initial OG concentration of 100 mg/L and the initial adsorbent dose of 2.5 g/L. The adsorption kinetic process of AS-GO conformed to the pseudo-second-order and Langmuir models. The spontaneous and endothermic adsorption of OG occurred in the adsorption process. The main adsorption mechanisms were electrostatic, π–π and hydrogen bonding interactions in the reaction process. After four cycles of AS-GO, it maintained high removal efficiency owing to its remarkable stability. The scheme of GO modified with AS could hinder the agglomeration of GO and provide more active sites, which would further enhance the adsorption properties and expand its application in water purification.

Effect of concentration GO and diamond wax and method of introducing additives on morphology and properties of epoxy powder coating

The morphology and properties of epoxy powder coating with two additives based on allotropic forms of carbon, diamond, and graphene oxide (GO), were studied. The effect of concentrations and preparation methods on the dispersion of GO within the polymer matrix was investigated. Two methods of introducing coating additives were investigated, to the component blend before extrusion and dry-mixed with the sieved powder. The surface roughness, abrasive wear resistance, thickness, as well as glossing of the coating were analysed depending on the type, concentration, and applied method of preparation. The study showed that the quantity of agglomerates in polymer matrix depends on the applied dispersion method. The lowest number of GO agglomerates was obtained by GO sonication before mixing of raw materials. The relationship between the content of GO in the coating and the abrasion resistance was found. The lowest abrasive wear was found for coating with 0.3% GO introduced by extrusion. Both additives, GO and diamond, in various concentrations have an impact on the coating wear resistance.

Effect ofGOagglomeration on the mechanical properties of graphene oxide and nylon 66 composites and micromechanical analysis

AbstractNanoparticles are prone to aggregation in the matrix under the action of surface energy, chemical bonding, electrostatic attraction, and van der Waals forces. Based on the molecular dynamics method, the tensile properties of graphene oxide (GO)‐reinforced nylon 66 composites were simulated and calculated, and the stress–strain curves, atomic stress clouds, and changes in the number of hydrogen bonds were obtained for the composites under tensile loading, and the effects of GO agglomeration on the mechanical properties of GO/PA66 composites were analyzed. When the GO mass fraction accounted for 90.3%, 80.5%, and 70.6% of the model, respectively, the mechanical properties of the composites decreased by 15.4%, 4.5%, and 4.2%, respectively. Because GO agglomeration in the composites made it difficult to bond effectively between GO and PA66, the number of hydrogen bonds and the type of hydrogen bonds within the model, varied with the degree of aggregation. The changes in the number of hydrogen bonds and the type of hydrogen bonds during uniaxial stretching were simulated by molecular dynamics. The number of hydrogen bonds and the type of hydrogen bonds directly affect the mechanical properties of the composites. It can be seen from the atomic stress cloud diagram that the aggregation of GO makes the mechanical properties of GO fail to exert effectively. The main stress is on the C atoms in the outermost layer of GO, while the stress on the inner layer C atoms is relatively small. As the degree of GO agglomeration decreases, the stress on each C atom of GO lamellae tends to be uniform, which effectively brings into play the excellent mechanical properties of GO and improves the mechanical properties of the composite.

Oligoimide-Mediated Graphene Oxide-Epoxy Nanocomposites with Enhanced Thermal Conductivity and Mechanical Properties.

The current study reports the preparation of thermally conductive polymeric nanocomposites. For this purpose, two epoxy-based nanocomposites were prepared by dispersing a different type of functionalized graphene oxide (GO) nanofiller in each series. Both these GO nanofillers were functionalized by covalently bonding oligoimide chains on their surfaces. In one series, these oligoimide chains were prepared by reaction of 3,3′,4,4′-benzophenonetetracarboxylic dianhydride (BTDA) with a diamine 4,4′-methylenedianiline (MDA). While in the other case, BTDA was reacted with N,N′-[((propane-2,2-diylbis(4,1-phenylene))bis(oxy))bis(4,1-phenylene)]bis(4-aminobenzamide) (BDM) to mount oligoimide chains on the surface of GO. Both types of oligoimide chains have amino groups as chain-end functional groups. These modified GO nanofillers were added to the epoxy matrices separately to prepare their respective nanocomposites (MDA-B-GO-epoxy nanocomposites and BDM-B-GO-epoxy nanocomposites). The chain-end amino groups of oligoimide chains reacted with the epoxy ring developing a covalent bonding between oligoimide chains of GO and the epoxy matrix. Moreover, these oligoimide chains prevented the agglomeration of GO by acting as spacer groups leading to the uniform dispersion of GO in the epoxy matrix. Various analytical techniques were used to examine the attachment of oligoimide chains to the GO surface, and to examine the morphology, curing potential, mechanical strength, thermal stability, and thermal conductivity of the prepared nanocomposites. We demonstrated that the thermal conductivity of MDA-B-GO-epoxy nanocomposites increased by 52% and an increase of 56% was observed in BDM-B-GO-epoxy nanocomposites. Similarly, a significant improvement was observed in the mechanical strength and thermal stability of both types of nanocomposites.

β‐Cyclodextrin Anchor NiCo2S4 on Graphene to Enhance Electrochemical Performance of Supercapacitor

To construct high–energy‐density supercapacitors, an electrode material with high conductivity needs to be compounded with an electrode material with high capacitive properties. Herein, NiCo2S4‐β‐cyclodextrin graphene (CDG) composite material formed by growing NiCo2S4 nanoparticles on graphene oxide (GO) modified with β‐Cyclodextrin (β‐CD) is reported. The modification of β‐CD can tackle the problem of agglomeration of GO and acts as a bridge to increase the binding force between NiCo2S4 nanoparticles and substrates. Combining the benefits of the modified GO and NiCo2S4, the synthesized composite electrode exhibits excellent electrochemical properties of 1325.9 F g−1 at 1 A g−1 and rate capability of 55.5% as current density increases from 1 to 7 A g−1. Moreover, the asymmetric device, fabricated with NiCo2S4‐β‐CDG as the positive electrode and active carbon as the negative electrode, exhibits a maximum energy of 30.72 Wh kg−1 at 1.28 kW kg−1 power density.

Effect of Polycarboxylate-Silane Modified Graphene Oxide Composite on the Properties of Cement Pastes.

As a nano-carbon material with excellent properties, Graphene oxide (GO) has been widely used in cement-based materials, and the negative effect of paste workability caused by GO agglomeration has also been widely concerning. In this study, a polycarboxylate-silane modified graphene oxide composite (PSG) was prepared by coupling polycarboxylate molecules to the surface of graphene oxide (GO) via a reaction with vinyl triethoxysilane. The effects of GO and PSG on the cement paste and the mechanisms underpinning these effects were investigated using fluidity and rheological parameter measurements, and ion concentration and zeta potential analyses. It was found that, in the aqueous phase of the paste, the polycarboxylate molecular chains on the surface of the PSG complexed with calcium ions (Ca2+), thereby preventing Ca2+ from bridging the GO sheets, and thus stabilizing the surface potential and the electrostatic repulsion. This prevented the PSG from forming an agglomerate structure such as that formed by GO under the same conditions, thereby substantially enhancing workability of paste with nano-carbon material. This study provides some new foundations and ideas for the further application of graphene oxide materials in cement-based materials.

Two-step surface functionalization/alignment strategy to improve CO2/N2 separation from mixed matrix membranes based on PEBAX and graphene oxide

In this study, a simple method to prepare mixed matrix membranes (MMM) based on Pebax with functionalized/oriented graphene oxide (GO) nanosheets is presented to improve CO2/N2 separation. First, the GO nanosheets were surface modified with different amounts of m-phenylenediamine (mPD) to maximize the CO2 adsorption affinity and minimize GO agglomeration within the matrix. Then, an external electric field was applied to organize/orient the GO nanosheets (modified and unmodified) during membrane preparation. The separation performance results showed that the CO2 permeability of unmodified and amine-functionalized GO-filled MMM respectively increased by 1.7 and 2.1 times compared to the neat matrix. This improvement is attributed to the high affinity of amino groups for CO2 uptake. Furthermore, applying a vertical electric field increased the CO2 permeability compared to a random GO orientation state by 1.3 and 2.8 times for the unmodified and modified GO-filled MMM, respectively. This significant improvement is related to a lower tortuosity in the membrane, improving the passage of gas molecules. Overall, the combination of surface treatment (amino group) and orientation (electric field) on GO nanosheets leads to better CO2 permselectivity for the membranes studied.

Graphene and its Effect on the Structural and Optical Properties of TiO2 Nano Thin Films Prepared by PLD Technique

In this study, thin films were prepared from pure titanium dioxide doped with graphene (1, 3, 5, 7%) wt using pulsed laser deposition (PLD) technique. The X-ray diffraction results showed that the prepared films were polycrystalline with a quaternary structure. It is noted that there are diffraction peaks corresponding to the levels (101, 004, 200, 211), and in the preferential direction (101), we notice that the intensity of the peak (101) decreases with increasing doping with the appearance of a new peak when doping at rates (5, 7%)and angle (26.5 ) This peak represents graphene oxide, and that the grain size decreased with increasing doping with graphene, where the grain size ranged between (20-40) nm. EDX analysis also shows that the results of the ratios were close to the required ratios, The results showed in the scanning electron microscope that the increase in the percentage of doping leads to the crystallization and agglomeration of graphene oxide and its rise over the Titanium dioxide (TiO2) until the surface reaches the state of collapse. The optical properties revealed an increase in the value of the energy gap by increasing the doping with graphene oxide, as it ranged between (3.15-3.7) eV.

Behavior of two classes of organic contaminants in the presence of graphene oxide: Ecotoxicity, physicochemical characterization and theoretical calculations

Graphene oxide (GO) production has increased considerably and therefore its presence in the environment is inevitable. When in aquatic environment GO can interact with co-existing compounds, modifying their toxicities for several organisms. However, the toxic effects of co-exposure of GO and organic compounds are rarely reported in the literature. Herein, we studied the behavior of four organic aquatic contaminants found in surface water such as 2-phenylbenzotriazoles (non-Cl PBTA-9 and PBTA-9) and phenoxyphenyl pesticides, pyriproxyfen (PYR) and lambdacyhalothrin (LCT), in the presence of GO. GO reduced 90% and 83% of the toxicity of non-Cl PBTA-9 and PBTA for Daphnia. When PBTAs were adsorbed onto GO surface their interactions caused GO agglomeration (up to 20 mm) and consequent precipitation, making PBTAs less bioavailable. PYR and LCT's toxicities increased up to 83% for PYR and 47% for LCT in the presence of GO, because their adsorption on GO lead to the stabilization of the suspensions (up to 0.5 μm). Those particles were then easily ingested and retained in the digestive tract of the daphnids, triggering the Trojan horse effect. Based on theoretical calculations we observed that PBTA compounds are planar, electron-poorer and more reactive than the studied pesticides, suggesting a better stability of the GO/PBTA complexes. PYR and LCT are nonplanar, electron-richer and less reactive towards GO than PBTAs, forming less stable GO complexes that could facilitate the desorption of pesticides, increasing toxic effects. Our results suggest that the properties of the organic toxicants can influence the stability of graphene oxide suspensions, playing a fundamental role in the modulation of their toxicity. Further research is needed for a deep understanding of the behavior of nanomaterials in the presence of contaminants and their effect in the toxicity of aquatic organisms.

High-temperature properties of cement paste with graphene oxide agglomerates

This study investigated the high-temperature properties of cement pastes with graphene oxide (GO) agglomerates at temperatures of 105 °C, 200 °C, 300 °C, and 450 °C. Generally, at ambient temperatures, incorporating GO can refine the pore structures and crystal sizes of calcium hydroxide, which is beneficial for the thermal resistance of a cement paste. In this study, during heat treatment, it was found that the water bound in GO agglomerates is negligible (from conducting a weight loss analysis). The GO agglomerates suppress the pore structure coarsening of cement pastes. The pore structure is finer and the total porosity is reduced by 8.5% with incorporation of 0.04% (by weight) GO at 300 °C which is close to critical point of water. With incorporation of 0.04% by weight GO in cement pastes at 200 °C, 300 °C, and 450 °C, the residual compressive strengths are 9.28%, 12.63%, and 10.83% higher than that of a reference sample, respectively.

Enhanced surface properties of a graphene oxide reinforced high-entropy alloy composite prepared by spark plasma sintering.

Graphene oxide (GO) has been proved to be a potential reinforcement. In this paper, 0.3 wt%, 0.6 wt%, and 1.0 wt% GO reinforced Fe22Co24Cr20Ni23Al11 high-entropy alloy (HEA) composites and pure HEA were synthesized by spark plasma sintering (SPS) to improve the surface properties of HEA. The surface properties including hardness and wear resistance of various samples were comparatively investigated. The experimental results indicated that the surface hardness and wear resistance were enhanced as the content of GO increased (when the GO content was less than 0.6 wt%), which were attributed to the grain refinement strengthening and lubrication effect of GO. However, as the content of GO incrementally increased to 1.0 wt%, the hardness exhibited a descending trend and the coefficient of friction (COF) increased, resulting from the agglomeration of GO. Accordingly, the residual indentation and wear track of HEA/0.6 wt% GO exhibited a minimum depth, which further confirmed the results of the nanoindentation and wear tests.

Graphene oxide as nano-material in developing sustainable concrete – A brief review

Nanomaterials are the most happening research field in material science. Hydration of cement grains and nano pore filling actions in cement matrix occurring at microscopic levels is greatly benefited by the superior surface area, aspect ratios, size, and greater mechanical characteristics of nano sized materials. Many researchers have used nanoparticles as cementitious materials in concrete. Graphene oxide (GO) is one among many nanomaterials with one of its sides in nano sized measurement and the other two sides are on a bigger scale. One of the advantages of GO over other nanoparticles is that the oxygen functionalities and can be easily dispersed under an aqueous medium. This paper sheds light on brief information about nanotechnology, nanomaterials application in concrete, characterization of GO, and various key researches in the usage of GO in producing concrete of desirable properties. Mainly, GO increases the performance of the resulting cement concrete by creating a strong covalent bond with hydration results like C-S-H. Using polycarboxylate ether and silica fumes the dispersion properties can be effectively improved without forming GO agglomerates. High-Performance cement concrete mixes can be produced by making GO form great bonds with other admixtures.

Texture evolution and corrosion behaviour of Sn–1.5 wt% Cr coatings containing Graphene oxide

ABSTRACT Sn–1.5 wt% Cr coating incorporated with varying quantity of Graphene oxide (GO) were deposited using electrodeposition technique on mild steel strip using aqueous electrolyte bath. The aqueous bath was dispersed with GO with increasing concentrations in mg/L (31.2, 62.5, 93.7, 125 and 156.2). All the coatings exhibited compact morphology and contained Sn and Cr-oxide phases (CrO2 and Cr2O3). Potentiodynamic polarisation and impedance spectroscopy techniques showed that the coating corrosion resistance increased for the initial addition of GO till Sn–Cr–GO2 coating (from 62.5 mg/L of GO) and it decreased thereafter for higher GO additions. The corrosion current density value exhibited by pristine Sn–Cr, Sn–Cr–GO2 and Sn–Cr–GO5 (from 156.2 mg/L of GO) was 1.38, 0.5 and 4.09 µA/cm2, respectively. Characterisation of the coating texture showed that between all the coatings, low angle grain boundary fraction was highest for Sn–Cr–GO2 coatings. The highest corrosion resistance was on account of special impermeable and inert properties of GO which was uniformly distributed in the coating matrix and the presence of a large fraction of low energy low angle grain boundaries. High corrosion rate in the case of Sn–Cr–GO5 coatings was attributed to the agglomeration of GO in the coating matrix which resulted in non-uniform coating morphology with high surface defects.