Agglomeration Of Graphene Oxide Research Articles

Direct and controlled device integration of graphene oxide on Quartz Crystal Microbalance via electrospray deposition for stable humidity sensing

Integration of advanced and functional materials onto conventional sensing platforms can improve the device performances and even discover new applications. For piezoelectric resonant sensors, an addition of sensing materials can induce damping and hinder a stable device operation. Hence, the development of efficient method for materials integration is important to ensure high-performance and reliable sensor operation. This work presents a direct and precisely controlled integration of graphene oxide (GO) using the electrospray deposition (ESD) onto a 10 MHz Quartz Crystal Microbalance (QCM) for humidity sensing. The proposed ESD method achieves a high mass resolution of a few nanograms. Moreover, the GO uniformly coats across the sensing electrode region as it acts as a ground electrode during ESD. The proposed ESD method also works for a wide range of nanomaterials, such as carbon nanotubes, tin oxide, and silicon carbide micro-and nano-powders. Compared to the conventional drop-casting and dip coating approaches, our method ensures minimal GO agglomeration, resulting in a stable QCM-oscillator operation in a wide range of relative humidity from 11% to 97%. The measurement sensitivity increases with an amount of GO, but less GO results in better noise and detection limit performances. The results shed light on the importance of selecting an optimal amount of sensing materials for stable sensor operations.

Dispersion of silane-functionalized GO and its reinforcing effects in cement composites

The agglomeration of graphene oxide (GO) in alkaline media fundamentally restricts its reinforcement efficiency in cement composites . We investigate a method of enhancing the dispersion and reinforcement efficiency of GO via functionalization using 3-aminopropyltriethoxy silane (APTS). Our results indicated that functionalization improved the dispersion of GO in a pore solution by up to 60% primarily due to steric hindrance and electrostatic repulsive effects. Strong interactions between the silane-functionalized GO (FGO) and cement hydration products via residual oxygen functional groups on GO (confirmed by FTIR and XPS) could fundamentally improve reinforcing effects. FGO samples provided higher heat flow peaks due jointly to the nucleation effect of GO and the pozzolan reaction of silica in silane. At the similar loadings of 0.02%, FGO increased workability by up to 17%, alongside compressive and tensile strength increments of 19% and 31%, respectively at 28 days compared with the reference GO. These findings demonstrated the effectiveness and potential of enhancing nano-reinforcing effects of GO in cement composites by improving dispersion capacity while ensuring strong interactions between GO and cement hydration products. • Silane-functionalized GO (FGO) showed better dispersion capacity in an alkaline environment compared to GO. • The combination of the nucleation effect of GO and the pozzolan reaction between silane and CH promoted the hydration peaks. • Strong interactions between the FGO and cement hydration products could fundamentally improve reinforcing effects.

Graphene oxide-coated sand for improving performance of cement composites

Graphene oxide (GO) was chemically bonded on sand through amino functional groups to avoid the GO agglomeration in the cement matrix. The effects of GO-coated sand (0.1% GO loading) on the micro- and macro-properties of cement composites were investigated. The workability of the GO-sand sample was largely comparable to that of the reference, indicating offsetting of the negative effect of GO on workability. Furthermore, by using GO-coated sand, water absorption was reduced by up to 20% while associated compressive and tensile strengths improved by ∼15% and 34%, respectively, at 28 days of age. These improvements were due to the strong covalent bonds between GO and sand. Such bonds could prevent the detachment of GO and its agglomeration within the matrix. In addition, GO at the interface and its bond to the cement paste could lead to a densified microstructure, a decrease in interfacial transition zone (ITZ) thickness, an improvement in the toughness of the ITZs, and thus a stronger interface. These results demonstrated the potential of using GO-coated sand in cement composites to deliver significant enhancement of both ductility and durability.

Enhancing oxygen reduction reaction performance via CNTs/graphene supported iron protoporphyrin IX: A hybrid nanoarchitecture electrocatalyst

In spite of disadvantages of limited activity and poor stability, MN4-complexes have created remarkable attention in the scientific community, energy field in particular, due to their applicability in oxygen reduction reaction (ORR) electrocatalysis. These disadvantages can be nullified considerably by using graphene oxide (GO) and carbon nanotubes (CNTs) as carbon supports due to their large surface area and high conductivity. Having limitation of tendency of agglomeration, GO may result to have detrimental effect on the ORR activity of MN4-complexes. In order to suppress the agglomeration of GO, herein, CNTs were effectively utilized. The binary carbon material was loaded with Hemin (H) molecule in a different ratio to form a H@CNTs/rGO composite. The electrochemical results indicated superior activity of H@CNTs/rGO (E1/2 = 89 mV) as compared to H@CNTs (E1/2 = 81 mV), H@rGO (E1/2 = 86 mV) and commercial 20% Pt/C (E1/2 = 84 mV). The characterization data revealed that the addition of CNTs could effectively suppress the agglomeration of rGO, thereby increasing area for the hemin molecule to get adsorbed on both nanocarbons, resulting increment of active sites for ORR. This work opens the opportunities for enhancement of various catalytic performances of metal complexes using nano-carbons.

Preparation, characterization and microhardness measurements of hybrid nanocomposites based on PMMA + P(VDF–TrFE) and graphene oxide

The polymer nanocomposites samples of the poly (methyl methacrylate) (PMMA)—poly (vinylidene fluoride–trifluoroethylene) P(VDF–TrFE) with graphene oxide (GO) were prepared by solution casting method. The impact of GO on electroactive polar β-phase of PMMA + P(VDF–TrFE) was investigated through the Fourier transform infrared spectroscopy (FTIR) and atomic force microscopy. The mechanical properties of nanocomposites samples have been investigated by measurement of microhardness. The value of microhardness and indentation depends on applied load on samples. The experimental result suggests that mechanical properties of samples decrease in presence of GO due to decrease in uniaxial orientation or agglomeration of GO. Surface characteristics such as surface free energy, interfacial free energy and hydrophobicity were determined by measuring the contact angle.

The synergic effects of metakaolin and polycarboxylate-ether on dispersion of graphene oxide in cementitious environments and macro-level properties of graphene oxide modified cement composites

Studying the effects of pozzolanic materials such as silica fume, fly ash, and metakaolin (MK) on dispersion of graphene oxide (GO) in cementitious environments has attracted interest in recent years. In this research, the potential of MK particles as an impediment against GO agglomeration in high alkaline environments is investigated. Despite the exhibited results in previous studies that the particles of pozzolans can inhibit the agglomeration of GO in cementitious environments by consuming Ca(OH)2 besides the mechanical separation of GO sheets, the results of the present study revealed that MK particles alone could not prevent GO nanosheets from clustering, physically or chemically. However, based on UV–vis spectroscopy and SEM-EDS analysis results, the incorporation of MK particles with Polycarboxylate-ether (PCE) significantly ameliorates the dispersion and time-dependent stability of GO nanosheets in simulated cement pore solution. Indeed, in this case, the anchoring characteristic of the negative surface charge of MK particles besides the steric hindrance effect of PCE’s side chains can reduce the possibility of the interaction between GO nanosheets and calcium ions in cementitious environments. Moreover, the improved stability of MK-PCE modified GO suspensions ensures the permanence of the desired dispersion of GO in the alkaline medium of cement composites, which is advantageous for enhancing the mechanical and transport properties of cement composites. In this research, the results of compressive strength, flexural strength, flexural modulus, toughness, and ultrasonic pulse velocity tests on MK-GO incorporated cement paste samples after 28 days of curing showed an enhancement by 27.6%, 36.3%, 49.8%, 42.0%, and 5.0%, respectively compared to the reference sample. This improvement is primarily due to the beneficial effects of MK-PCE to make GO play a better reinforcing role in cement composites.

Electrostatic self-assembly to fabricate ZnO nanoparticles/reduced graphene oxide composites for hypersensitivity detection of dopamine

This study introduces the self-assembly method to fabricate Zinc Oxide (ZnO) decorated reduced Graphene Oxide (ZnO-rGO) composites with higher sensitive for detection of dopamine (DA), one of the most common biomarkers of Parkinson’s disease. The approach is reported to self-assembly Graphene Oxide (GO) and ZnO nanoparticles (NPs) modified by 3-aminopropyl triethoxysilane (APTES), forming ZnO-GO composites, then ZnO-rGO composites were obtained by electrochemical reduction of ZnO-GO composites. Utilizing differential pulse voltammetry (DPV), we found ZnO-rGO composites fabricated by the method of self-assembly reduced the agglomeration of ZnO and GO and showed a higher sensitivity for detection of DA than the dopamine electrochemical sensor previously reported. The fabricated sensor showed a linear dynamic range on 5–70 μM with a LOD of 0.167 μM (S/N = 3) and a sensitivity of 458nA/μM in response to DA. Finally, the as-prepared ZnO-rGO composite displayed an excellent detection recovery of 98.8 ~ 101.2% in human serum.

Study on the liquid crystal display mask photo‐curing of photosensitive resin reinforced with graphene oxide

AbstractGraphene oxide has the characteristics of high specific surface area, high strength, and high modulus. The tensile and compressive properties of the cured resin part can be reinforced after the graphene oxide is mixed into the photosensitive resin. A self‐developed liquid crystal display (LCD) mask photo‐curing machine is adopted to prepare photosensitive resin parts mixed with graphene oxide. The influence of graphene oxide content on the surface roughness, tensile, and compressive properties of the cured resin is analyzed by the combination of finite element simulation and experiment. It is concluded that the accumulation of graphene oxide is the main reason affecting the tensile and compressive properties of the cured part. By applying ultrasonic vibration and extending the time of magnetic stirring at 80°C, the dispersion uniformity of graphene oxide is improved, the agglomeration of graphene oxide is reduced, and the tensile and compressive strength of cured parts are strengthened.

Synthesis and Physicochemical Transformations of Size-Sorted Graphene Oxide during Simulated Digestion and Its Toxicological Assessment against an In Vitro Model of the Human Intestinal Epithelium.

In the last decade, along with the increasing use of graphene oxide (GO) in various applications, there is also considerable interest in understanding its effects on human health. Only a few experimental approaches can simulate common routes of exposure, such as ingestion, due to the inherent complexity of the digestive tract. This study presents the synthesis of size-sorted GO of sub-micrometer- or micrometer-sized lateral dimensions, its physicochemical transformations across mouth, gastric, and small intestinal simulated digestions, and its toxicological assessment against a physiologically relevant, in vitro cellular model of the human intestinal epithelium. Results from real-time characterization of the simulated digestas of the gastrointestinal tract using multi-angle laser diffraction and field-emission scanning electron microscopy show that GO agglomerates in the gastric and small intestinal phase. Extensive morphological changes, such as folding, are also observed on GO following simulated digestion. Furthermore, X-ray photoelectron spectroscopy reveals that GO presents covalently bound N-containing groups on its surface. It is shown that the GO employed in this study undergoes reduction. Toxicological assessment of the GO small intestinal digesta over 24 h does not point to acute cytotoxicity, and examination of the intestinal epithelium under electron microscopy does not reveal histological alterations. Both sub-micrometer- and micrometer-sized GO variants elicit a 20% statistically significant increase in reactive oxygen species generation compared to the untreated control after a 6 h exposure.

Highly-efficient microwave absorptivity in reduced graphene oxide modified with PTA@ imidazolium based dicationic ionic liquid and fluorine atom

This study introduces fabrication of well-designed modified graphene oxide (GO) with highly microwave (MW) absorption performance, which includes covalently connection of the phosphotungstic acid-imidazolium based dicationic ionic liquid (PTA@ Imid diIL) and Fluorine atom on the surface of GO. The structure and morphology of as-prepared PTA@ Imidazolium based dicationic ionic liquid interlocked on the surface of fluorinated graphene oxide (PTA@ Imid diIL- FGO) were specified by XPS, FTIR, Raman spectroscopy, FESEM and TEM. The unique structure of GO after being connected to PTA@ Imid diIL and fluorine atom not only effectively reduced the agglomeration of GO, but also caused high polarity, high dielectric properties as well as multiple scattering and polarization. As an MW absorbing material the PTA@ Imid diIL- FGO/epoxy resin composites were created at various loading of PTA@ Imid diIL- FGO (10–60 wt %), and they absorbed strongly the MW in the 8.0–12.0 GHz range. For example the PTA@ Imid diIL- FGO/epoxy resin composite exhibited the reflection loss (RL) values of −39 dB at loading of 50 wt % PTA@ Imid diIL- FGO with absorber thickness of 2.0 mm and the bandwidth consistent with the RL less than −10 dB can reach 2.5 GHz (from 9.5 GHz to 12 GHz). This research showed that the PTA@ Imid diIL- FGO with polar dangling functional groups is useful to absorb the enhanced MW properties.

Surface abrasion resistance of high-volume fly ash concrete modified by graphene oxide: Macro- and micro-perspectives

Recent studies have demonstrated that graphene oxide (GO) can be used as a promising nano-sized additive to improve the mechanical properties and durability performances of cement composites. In this laboratory study, the effect of admixed GO on the properties of high-volume fly ash (HVFA) concrete, especially its surface abrasion resistance, was investigated. Compressive strength, microhardness, and tribological properties of HVFA mixtures were also measured to investigate their possible correlations with the abrasion resistance. The addition of GO (up to 0.1% by weight of cementitious materials) increased the compressive strength at the macro level and friction coefficient at the micro level, both of which could be related to the surface abrasion resistance of HVFA concrete. Microhardness and scratch test results showed that the HVFA mixtures achieved the best performance with GO admixed at 0.05 wt%, which was confirmed by the microstructure investigations by XRD and SEM/EDS. In addition, the agglomeration of GO may occur at a dosage higher than 0.05 wt%.

Synthesis of nanoSiO2@graphene-oxide core-shell nanoparticles and its influence on mechanical properties of cementitious materials

Graphene oxide (GO) has enormous potential to improve properties of cementitious materials. Well dispersed GO in hardened cement matrix could be more effective in strengthening concrete compared to aggregated GO. While GO agglomeration is somewhat inevitable due to its fine nature, the degree of agglomeration could be tuned through particle separation. In this study, nanoSiO2@graphene-oxide (NS@GO) nanoparticles were synthesized using GO and colloid nanoSiO2 (NS) by a electrostatic self-assembly method. NS, GO and the prepared NS@GO were characterized by x-ray diffraction, scanning electron microscopy, atomic force microscopy, and Fourier transmission infrared, and, the influence of NS@GO addition on the mechanical properties of cementitious composites was investigated. The results show that NS@GO can increase the flexural strength of cement composites by 49.2% at later age. A “sandwich effect” was proposed as an important reinforcing mechanism of NS@GO based on the microstructure and hydration products of NS@GO added composites. Compared with the simple NS-GO blend, NS@GO can better maintain the spatial structure of GO when mixed with cement. In addition, there would be more interactions between calcium silicate hydrates and GO during the cement hydration process, which contributes to the strength gain in NS@GO added mix. The research sheds new light on using GO and NS to optimize cementitious material design, as well as spatial coordination of different types of nanoparticles.

GO-modified flexible polymer nanocomposites fabricated via 3D stereolithography

Graphene oxide (GO) induced enhancement of elastomer properties showed a great deal of potential in recent years, but it is still limited by the barrier of the complicated synthesis processes. Stereolithography (SLA), used in fabrication of thermosets and very recently in “flexible” polymers with elastomeric properties, presents itself as simple and user-friendly method for integration of GO into elastomers. In this work, it was first time demonstrated that GO loadings can be incorporated into commercial flexible photopolymer resins to successfully fabricate GO/elastomer nanocomposites via readily accessible, consumer-oriented SLA printer. The material properties of the resulting polymer was characterized and tested. The mechanical strength, stiffness, and the elongation of the resulting polymer decreased with the addition of GO. The thermal properties were also adversely affected upon the increase in the GO content based on differential scanning calorimetry and thermogravimetric analysis results. It was proposed that the GO agglomerates within the 3D printed composites, can result in significant change in both mechanical and thermal properties of the resulting nanocomposites. This study demonstrated the possibility for the development of the GO/elastomer nanocomposites after the optimization of the GO/“flexible” photoreactive resin formulation for SLA with suitable annealing process of the composite in future.

Synthesis of Cu/rGO composites by chemical and thermal reduction of graphene oxide

In this work, synthesis of copper/reduced graphene oxide composites to increase the electrical conductivity of copper matrix has been carried out. Pure copper particles were mixed with 0.28 wt%, 1.1 wt% and 2.5 wt% graphene oxide (GO) contents. Different reduction methods were chosen to synthetize the Cu/rGO composite material: chemical reduction with hydrazine, thermal treatment at 815 °C in argon atmosphere. Characterization of the Cu/rGO composite disks was carried out by optical microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy and Raman spectroscopy. Vickers Hardness and the electrical conductivity measured by Van der Pauw method of the Cu/rGO composites were analyzed. All the Cu/rGO disks showed lower hardness values than the Cu matrix. Microstructure of Cu/rGO composites is dominated by the presence of pores where GO agglomerates are accumulated and whose distribution and magnitude depends on the weight percentage of GO and the reduction process. Porosity percentage and pore size of Cu/rGO disks increase with GO content. Combination of chemical reduction with thermal treatment provides the most homogeneous microstructures with the smallest pore size and porosity percentage. Combination of both reduction treatments promotes more pathways for carrier transport within the reduced graphene oxide network structure, expanding areas of long-range conjugated structures and, consequently, increasing the electrical conductivity in the rGO/copper composites. Our research evidences that the Cu/rGO composites after chemical and thermal reduction increases the electrical conductivity, independently on the GO content, with respect to the pure copper matrix.

Ultra-low graphene oxide loading for water permeability, antifouling and antibacterial improvement of polyethersulfone/sulfonated polysulfone ultrafiltration membranes

The aqueous dispersion of graphene oxide (GO) was employed as additive to fabricate antifouling and antibacterial polyethersulfone (PES)/sulfonated polysulfone (SPSf)/GO mixed matrix membranes (MMMs) by the non-solvent induced phase separation (NIPS). The effect of different amounts of GO on the morphology and performance of MMMs were studied. The results showed that the casting solution exhibited an increasing trend in viscosity with increment in GO concentration (from 0 to 0.016 wt%) owing to the hydrogen bonding (H-bonding) interaction among GO, H2O and SPSf. Raman and molecular dynamic (MD) simulations analyses confirmed that there existed H-bonding interaction among SPSf, GO and H2O. Specifically, the agglomeration of GO was inhibited and stable homogeneous casting solution was obtained. Meanwhile, the H-bonding interaction also played a key role in the MMMs structure and improved properties. It was found that GO nanosheets were uniformly embedded to form many cellular-like voids in the asymmetric PES/SPSf/GO MMMs with a sponge-like structure. The pure water flux of the MMMs with a very low GO content of 0.012 wt% was up to 816.9 L/m2h and the rejection of bovine serum albumin (BSA) was more than 99.2% under a pressure of 0.1 MPa. Additionally, the mechanical properties of MMMs was also improved with the increase of GO content. Importantly, the MMMs displayed excellent antifouling and antibacterial performance. A high fouling recovery (94.2%) and antibacterial rate (90.0%) against Escherichia coli (E. coli) obtained were attributed to improved hydrophilicity, enhanced negative charge and GO nano-size effect. In summary, our study provides a simple approach to tailor MMMs with the enhancement of permeation, antifouling and antibacterial properties at a very low content of GO.

Removal of emulsified and dissolved diesel oil from high salinity wastewater by adsorption onto graphene oxide

Large quantities of oily wastewaters are produced globally from oil extraction and refining industries containing low concentrations of dissolved and finely emulsified oils. These waters are difficult to treat within a small footprint as often necessary, especially on offshore sites, and often contain high salinity making many treatment methods ineffective. In this study the use of graphene oxide (GO) as an adsorbent is investigated using diesel as a representative oil. GO demonstrated a high adsorption capacity of 1335 mg/g according to the Freundlich isotherm and based on theoretical surface area was likely due to limited multi-layer adsorption. Increasing salinity to 1% increased adsorption capacity by 75%, remaining constant thereafter, confirming the suitability for the material for saline produced water remediation. Adsorption was extremely rapid, reaching more than 90% of the equilibrium capacity within 4 min, and was represented best by a pseudo-second order kinetic model. Fixed bed column tests confirmed the ability for excellent removal capacities under a short contact time and good regeneration, indicating the potential of GO for industrial oil-water emulsion separation applications. Based on careful analysis of isotherm and kinetic data, in conjunction with theoretical considerations, a rapid multi-layer physisorption mechanism, influenced by GO agglomeration, is proposed.

Fate and Transformation of Graphene Oxide in Estuarine and Marine Waters.

The possibility of graphene oxide (GO) exposure to the environment has spurred several studies investigating the fate of this nanoparticle (NP). However, there is currently little or no data on the fate of GO in estuarine and marine waters. This study investigated the aggregation, sedimentation, and transformation of GO in saline waters, considering the roles of salinity (0-50 ‰), light (visible light and solar irradiation), and aging, among others. The attachment efficiency of GO reached unity at 1.33 ‰. The sedimentation rate of GO increased with salinity up to 10 ‰ after which it decreased due to formation of ramified GO agglomerates and media density. On the basis of the sedimentation rate determined at 30 ‰ (0.121 m/d), the residence time of GO agglomerates in the euphotic zone of typical open oceans will exceed 500 days. Aging in the presence of visible light increased the relative abundance of the GO's aromatic (C-C/C=C) fraction, reducing the NP. Reduction of GO in visible light was confirmed via UV-vis and Raman spectroscopic techniques. Reduction of GO was faster under solar irradiation. This study demonstrates that when introduced into saline waters, GO will undergo a range of transformations affecting its fate and potential effects to aquatic organisms.

"Ultramixing": A Simple and Effective Method To Obtain Controlled and Stable Dispersions of Graphene Oxide in Cell Culture Media.

The last decade has seen an increase in the application of graphene oxide (GO) in the biomedical field. GO has been successfully exploited for its ability to deliver many kinds of drugs into target cells. However, GO toxicity assessment is still controversial. Several studies have demonstrated that GO protein coating is crucial to alleviate the material's toxicity. Besides, coronation leads to the formation of big agglomerates, reducing the cellular uptake of the material and thus its therapeutic efficiency. In this work, we propose a simple and efficient method based on rapid (ultra-turrax, UT) mixing to control protein corona formation. Using the UT protocol, we were able to reduce GO agglomeration in the presence of proteins and obtain stable GO dispersions in cell culture media. By labelling GO with luminescent nanoparticles (quantum dots), we studied the GO internalization kinetic and efficiency. Comparing the "classic" and UT protocols, we found that the latter allows faster and more efficient internalization both in macrophages and HeLa cells without affecting cell viability. We believe that the use of UT protocol will be interesting and suitable for the preparation of next-generation GO-based drug-delivery platforms.

The Preparation and Properties of Nanocomposite from Bio-Based Polyurethane and Graphene Oxide for Gas Separation.

Petroleum depletion and climate change have inspired research on bio-based polymers and CO2 capture. Tung-oil-based polyols were applied to partially replace polyether-type polyols from petroleum for sustainable polyurethane. Tung-oil-based polyurethane (TBPU), was prepared via a two-step polycondensation, that is, bulk prepolymerization and chain extension reaction. The graphene oxide (GO) was prepared via Hummer’s method. Then, TBPU was composited with the GO at different ratios to form a TBPU/GO hybrid film. The GO/TBPU films were characterized by fourier transform infrared spectroscopy (FTIR), differential scanning calorimeter (DSC), thermal gravimetric analysis (TGA) and scanning electron microscope (SEM), followed by the measurement of mechanical properties and gas permeability. The results showed that the addition of tung-oil-based polyols enhanced the glass transition temperature and thermal stability of TBPU. The mechanical properties of the hybrid film were significantly improved, and the tensile strength and elongation at break were twice as high as those of the bulk TBPU film. When the GO content was higher than 2.0%, a brittle fracture appeared in the cross section of hybrid film. The increase of GO content in hybrid films improved the selectivity of CO2/N2 separation. When the GO content was higher than 0.35%, the resulting GO agglomeration constrained the gas separation and permeation properties.

Barriers to achieving highly dispersed graphene oxide in cementitious composites: An experimental and computational study

Graphene oxide (GO) has aroused the interests of researchers as an effective nano-reinforcement for cementitious composites. However, its application to the cementitious environments is severely limited mainly because of its agglomeration. This paper investigates the effect of influential factors including cations, pH value and surfactants on GO agglomeration in the cementitious environments to achieve highly dispersed GO-cement composites. In addition to the experimental studies, molecular dynamics simulations and quantum calculations were also employed to help better understanding of the mechanisms. Results show that multivalent cations like Ca2+ are more detrimental in case of GO agglomeration in the cementitious environment, compared to the monovalents. Moreover, it was found that there is a correlation between the dispersion state of GO and intensity of alkali media of cementitious environment. In mild alkali media, an increment in pH from 7 to about 10.9 causes more ionization and electrostatic repulsion, which leads to better dispersion. However, at high alkali media with pH larger than 10.9 GO dispersion undergoes reduction when pH increases. It is because GO loses the majority of its functional groups and eventually agglomerates. Among examined surfactants, polycarboxylate ether based superplasticizer shows the best capability to disperse GO in the cementitious environment.