Thiol-functionalized Graphene Research Articles

Synthesis, Characterization, And Application of Graphene Oxide-Based Nanocomposite for Furfural Adsorption

Objective: The objective of this study is to synthesize, characterize, and apply a novel graphene oxide-based adsorbent for the organic contaminant furfural, aiming to develop a new material with the capacity for removal of this heterocyclic aldehyde via the adsorptive method. Theoretical Framework: This empirical study utilized a bibliographic procedure to synthesize the adsorbents, investigate their efficacy in adsorbing furfural, and observe the kinetic characteristics of adsorption. The synthesized material was characterized to classify it based on its physical aspects. Method: The methodology adopted for this research includes the synthesis of the adsorbents, the evaluation of their adsorptive capacity for furfural removal, conducting adsorption kinetics, and studying the equilibrium and thermodynamics of adsorption. For the characterization of the adsorbents, analyses were performed using infrared spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, dynamic light scattering, X-ray diffraction, and Raman spectroscopy. Results and Discussion: The results revealed that non-functionalized graphene oxide did not exhibit the capacity to adsorb furfural. The model that best fit the experimental data for the adsorption of furfural on thiol-functionalized graphene oxide was the pseudo-second-order model, indicating multilayer adsorption, applicable in both homogeneous and heterogeneous systems as mentioned in the literature. The thiol-functionalized graphene oxide demonstrated a furfural removal efficiency of approximately 60% under the studied conditions. According to the model, the thiol-functionalized graphene oxide exhibited a maximum adsorption capacity of 722.12 mg.g-1. Research Implications: This research contributes scientifically as this application has never been performed and presents a new material as an adsorbent for furfural, expanding the collection of materials capable of partially removing this contaminant from the aqueous environment. Originality/Value: This study contributes to the literature by verifying that the adsorbents developed in this work had not been used for the adsorption of the contaminant furfural, thus providing a contribution to scientific research in the application of graphene oxide. The relevance and value of this research are evidenced by the synthesis of a new adsorbent capable of partially decontaminating the organic compound from an aqueous solution.

Highly Efficient Removal of Mercury Ions from Aqueous Solutions by Thiol-Functionalized Graphene Oxide

Mercury ion (Hg(II)) is one of the most prevalent and dangerous heavy metal ions in the environment, and its removal from water sources is a priority for public health and ecosystem conservation policies. Adsorption is a cost-effective and efficient method for removing heavy metal ions from aqueous solutions. In this study, the thiol-functionalized graphene oxide (GO-SH) was synthesized and used for efficient removal of Hg(II) from aqueous solutions. More than 98% of Hg(II) was efficiently removed by GO-SH within 36 h. The Hg(II) removal efficiency by GO-SH treatment was approximately double that by pure GO treatment. The adsorption behavior of Hg(II) on GO-SH was well described by the pseudo-second-order kinetic and the Freundlich isotherm models. Moreover, GO-SH exhibited good stability and reusability in the cycle experiments. Analysis of the adsorption mechanism showed that Hg(II) could be loaded onto the GO-SH surface by reacting with the sulfhydryl groups. This study demonstrates that GO-SH is a promising water purification material with a high efficiency for Hg(II) removal.

Preparation of degradable, biocompatible, conductive and multifunctional chitosan/thiol-functionalized graphene nanocomposite hydrogel via click chemistry for human motion sensing

As an auspicious multifunctional material, hydrogels have engendered a huge surge of interest worldwide because of their undeniable applications, particularly in wearable sensor fields. However, it has been a great challenge to simultaneously integrate flexibility, high electrical conductivity, strain sensitivity, self-healing property, biodegradability and non-drying property into a single hydrogel. In this work, the conductive biodegradable nanocomposite hydrogels based on chitosan (CS) and thiol-functionalized graphene oxide (GSH) were presented via “thiol-ene” click reaction. Remarkably, the compressive modulus and shape recovery of the nanocomposite hydrogels, totally increased by more than 400% and 300%, respectively, in comparison with the CS hydrogel. Furthermore, benefiting from the electroactive pathway generated by GSH in the hydrogel network, the flexible hydrogel sensors indicated strain sensitivity and the electrical conductivity of the obtained nanocomposite hydrogels reached 0.35 S/m. These excellent properties were demonstrated by human activity monitoring device in real time. Also, cytocompatibility of the hydrogels was also confirmed using L929 fibroblast cells. The fast gelation method proposed in this paper would be promising in fabricating smart conductive sensors used for biomedical diagnostics and wearable electronics.

Highly efficient ultrasonic-assisted preconcentration of trace amounts of Ag(I), Pb(II), and Cd(II) ions using 3-mercaptopropyl trimethoxysilane-functionalized graphene oxide–magnetic nanoparticles

The preparation and characterization of thiol-functionalized graphene oxide–iron oxide (Fe3O4–GO–SH) nanocomposites (novel magnetic adsorbents) for the simultaneous preconcentration and determination of heavy metal ions, such as Ag(I), Pb(II), and Cd(II), from water samples were carried out in the present research. The characterization of the resultant Fe3O4–GO–SH nanocomposites was performed by SEM, TEM, EDX, XRD, FT-IR, and VSM. The preconcentration optimization of pH solution, adsorbent amount, ultrasonic power for adsorption and desorption processes, adsorption time, and elution solvent type and concentration was performed by the ultrasonic-assisted magnetic solid-phase extraction. Under optimal conditions, linear ranges were found to be 20–1000 μg L–1 for Ag(I) and Cd(II) ions and 200–10,000 μg L–1 for Pb(II) ions with a regression coefficient of R2 > 0.99. The limits of detection for Ag, Pb, and Cd ions were 1.7 μg L–1, 14.1 μg L–1, and 0.9 μg L–1, respectively, and the limits of quantification for Ag, Pb, and Cd ions were 5.9 μg L–1, 47.3 μg L–1, and 3.2 μg L–1, respectively. The recovery rate of these metal ions for water samples (drinking water, tap water, swamp water, and wastewater from plating plants) ranged between 80 and 115%. Therefore, the proposed method can potentially be used for the simultaneous preconcentration and determination of heavy metal ions from real water samples, and its reusability can be easily carried out by the deionized water treatment.

Preparation of stable AgNPs@PAN/GO-SH nanocompsite by electrospinning for effective degradation of 4-nitrophenol, methylene blue and Rhodamine B

Polyacrylonitrile doped thiol-functionalized graphene oxide nanofibrous membranes loaded with silver nanoparticles (AgNPs@PAN/GO-SH) were synthesized by electrospinning. AgNPs@PAN nanocomposites were also synthesized by means of In-situ and UV reduction. The stability of AgNPs loaded on the composites were compared under different pH and agitation speeds, and the results showed that the stability of AgNPs in the composite from the new strategy was much better than that from the other two methods. The catalytic performance of AgNPs@PAN/GO-SH was also studied and the results indicated that AgNPs@PAN/GO-SH had good catalytic reduction performance. This study provided a feasible way for the design and synthesis of effective and stable composite for degradation of dyes in water.

Kinetics and thermodynamics of mercury adsorption onto thiolated graphene oxide nanoparticles

Mercury among heavy metals has significant worldwide importance due to major ecological effects. Numerous methods have been used to remove this metal from polluted wastewaters which adsorption by functionalized adsorbents is one of the most common methods. In the present study, graphene oxide nanoparticles were functionalized, magnetized and used for removing Hg(II) ions. In addition, FT-IR, TEM, SEM, EDS and VSM analyses were carried out to characterize the chemical, physical and surficial properties of thiol functionalized graphene oxide nanoparticles. Mercury removal experiments were done and confirmed the efficiency of the thiol-functionalized adsorbent. Additionally, adsorption trend was obtained in order to evaluate the fitness of experimental data by isothermal Langmuir, Freundlich and Dubinin-Radushkevich models in batch system. Furthermore, thermodynamic and kinetic calculations were carried out comprehensively. Results showed that Langmuir model (R2 = 0.995) and Freundlich model (R2 = 0.982) logically described the adsorption trend. Also, Dubinin-Radushkevich model offered a proper correlation (R2 = 0.997). The maximum adsorbing capacity of thiol-functionalized graphene oxide was estimated to be 129.7 mg.g−1 by Langmuir model. Thermodynamic calculations showed that Hg(II) adsorption reaction on GO/Fe3O4-Si-Pr-SH was spontaneous. Kinetic calculations confirmed that Hg(II) ion adsorption followed more accurately by pseudo-second order model than the pseudo-first order model. Generally, it was approved that thiol-functionalized graphene oxide nanoparticles can be effectively used to adsorb heavy metals and then separated easily from the liquid phase by magnetic field.

In situ remediation of mercury-contaminated soil using thiol-functionalized graphene oxide/Fe-Mn composite.

Mercury (Hg) contamination in soil is a paramount concern to the environment and public health. Yet, effective in situ remediation technologies have been lacking. In this study, a novel thiol-functionalized graphene oxide/Fe-Mn (SGO/Fe-Mn) composite was prepared and investigated for in situ immobilization of Hg in contaminated soil. Batch tests showed that application of SGO/Fe-Mn at doses of 0.4% and 0.8% effectively reduced H2O, H2SO4 and HNO3, CH3COOH, and CaCl2-extractable Hg by 90.3-98.9% and 96.5-98.9%, respectively, upon equilibrium after 72 d. An increasing of soil moisture content from 0 to 12.5% significantly enhanced the immobilization efficiency from 75.0% to 97.6%. XRD, FTIR, and XPS analyses suggested that the composite mainly immobilized Hg through surface complexation and chemical precipitation. Sequential extraction procedure demonstrated that the composite promoted the conversion of more accessible Hg (exchangeable and carbonate fractions) into the less accessible forms, i.e., oxides, organic matter, and residual fractions, resulting in substantially reduced environmental risk of Hg. The application of SGO/Fe-Mn enhanced soil cation exchange capacity, available N and K, and total organic carbon, and can be used to effectively improve soil properties. Moreover, immobilized Hg in soil by this composite remained stable over one year. The present study demonstrates the potential and viability of SGO/Fe-Mn for enhanced immobilization of Hg in soil and sediment.

An Ultra-High-Energy Density Supercapacitor; Fabrication Based on Thiol-functionalized Graphene Oxide Scrolls.

Present state-of-the-art graphene-based electrodes for supercapacitors remain far from commercial requirements in terms of high energy density. The realization of high energy supercapacitor electrodes remains challenging, because graphene-based electrode materials are synthesized by the chemical modification of graphene. The modified graphene electrodes have lower electrical conductivity than ideal graphene, and limited electrochemically active surface areas due to restacking, which hinders the access of electrolyte ions, resulting in a low energy density. In order to solve the issue of restacking and low electrical conductivity, we introduce thiol-functionalized, nitrogen-doped, reduced graphene oxide scrolls as the electrode materials for an electric double-layer supercapacitor. The fabricated supercapacitor exhibits a very high energy/power density of 206 Wh/kg (59.74 Wh/L)/496 W/kg at a current density of 0.25 A/g, and a high power/energy density of 32 kW/kg (9.8 kW/L)/9.58 Wh/kg at a current density of 50 A/g; it also operates in a voltage range of 0~4 V with excellent cyclic stability of more than 20,000 cycles. By suitably combining the scroll-based electrode and electrolyte material, this study presents a strategy for electrode design for next-generation energy storage devices with high energy density without compromising the power density.

Effective removal of inorganic mercury and methylmercury from aqueous solution using novel thiol-functionalized graphene oxide/Fe-Mn composite.

A novel thiol-functionalized graphene oxide/Fe-Mn (SGO/Fe-Mn) was investigated for aqueous Hg2+ and CH3Hg+ removal. Mercury were removed mainly through ligand exchange and surface complexation with surface active sites (i.e., -SH, OH, OCO, CC, SiO, and ππ bond). SH had the strongest binding ability with mercury, forming sulfur-containing organic matter or polymers with Hg2+, and sulfur-containing organometallic compounds or thiolate-like species with CH3Hg+. The BET sorption isotherm model well simulated the sorption isotherm data of Hg2+ (R2=0.995, qm=233.17 mg/g) and CH3Hg+ (R2=0.997, qm=36.69 mg/g), indicating a multilayer adsorption process. The mercury uptake was promoted with the increase of 3-MPTS content, adsorbent dosage, and pH (<5.5), whereas the uptake was inhibited by high pH (>5.5) and high concentrations of humic acid and electrolytes. SGO/Fe-Mn demonstrated high mercury uptake in simulated surface water/groundwater and in the presence of Pb, Cu, Ni, Sb, Cd and Zn. The mercury-laden SGO/Fe-Mn can be successfully regenerated and reused for three times with 98.1% and 67.0% of original Hg2+ and CH3Hg+ sorption capacity when 5% thiourea + 2 M KI was used as the desorbing agent. This study demonstrates potential and viability of SGO/Fe-Mn for mercury remediation.

Graphene and Disulfide-Based Framework As a Transition Metal-Free Electrode Material for Li-Ion Battery

For a brand-new electrode material with transition metal-free and high electrochemical performance for Li-ion battery (LIB), graphene and disulfide-based framework was designed and synthesized by hybridizing graphene and organic compounds. For the designing of the material, we focused on the four important electrochemical properties: specific capacity, potential sensitiveness, cyclic stability and high Li+/e- mobility. As a result, graphene framework with a layered structure constructed by the formation of disulfide bonds between terminal dithiol organic linker molecules and thiol-functionalized graphene sheets. The organic linker molecules play a role as pillars which maintains the framework structure and prevents restacking of graphene sheets. Various types of dithiol organics were investigated as linker components in GSF for evaluating the effect of its length or structure on electrochemical properties. As a result, distinctive electrochemical performance among the synthesized materials was observed depending on current density, implies the involvement of multiple Li-incorporation mechanisms. Based on the differential analyses and electrochemical impedance spectroscopy (EIS), the linker-dependent Li storage mechanism in GSFs was suggested. Also, reversible breakage-formation of disulfide bond within GSF was proved by ex-situ XPS analysis with varied state of charge (SOC), which represents self-healing functionality of the material. The GSF proposed in this study could be a promising electrode material for transition metal-free, low cost and high performance energy storage system.

Different approaches for preparing a novel thiol-functionalized graphene oxide/Fe-Mn and its application for aqueous methylmercury removal

A novel thiol-functionalized graphene oxide/Fe-Mn composite (SGO/Fe-Mn) was synthesized via three different methods, i.e., acetic acid method (SGO/Fe-Mn-ac), neutral method (SGO/Fe-Mn-ne), and ammonium hydroxide method (SGO/Fe-Mn-am). The composites were characterized and tested for aqueous methylmercury removal. SGO/Fe-Mn was prepared using 3-mercaptopropyltrimethoxysilane (3-MPTS) as a silanizing reagent, and hydrolyzed 3-MPTS mainly interacted with GO/Fe-Mn through surface oxygen-containing groups (i.e., OH, CO, epoxy COC, carboxyl OCO, and CO) and π-π interactions, partially through self-polymerization. SGO/Fe-Mn-am showed the largest hydrodynamic diameter, strongest π-π bond, fewest S oxidation products, most thiol groups, negative charge, sp3 defects, and FeOOH. Pseudo-second-order kinetic model and Langmuir and Freundlich isotherm models fitted well with methylmercury sorption kinetic and isotherm data, respectively, resulting in a CH3Hg+ maximum sorption capacity of 43.88mg/g for SGO/Fe-Mn-am, 36.33mg/g for SGO/Fe-Mn-ac, and 28.00mg/g for SGO/Fe-Mn-ne. The removal mechanism was described by electrostatic attraction, ligand exchange, and surface complexation. This study demonstrates potential and viability of SGO/Fe-Mn for enhanced immobilization of CH3Hg+ in surface water, groundwater, and soil/sediments.

Synthesis of one-dimensional gold nanostructures and the electrochemical application of the nanohybrid containing functionalized graphene oxide for cholesterol biosensing

This manuscript reports a new approach for the synthesis of one dimensional gold nanostructure (AuNs) and its application in the development of cholesterol biosensor. Au nanostructures have been synthesized by exploiting β-diphenylalanine (β-FF) as an sacrificial template, whereas the Au nanoparticles (AuNPs) were synthesized by ultrasound irradiation. X-ray diffractometer (XRD), scanning electron microscope (SEM) and energy dispersive analysis of X-rays (EDAX) have been employed to characterize the morphology and composition of the prepared samples. With the aim to develop a highly sensitive cholesterol biosensor, cholesterol oxidase (ChOx) was immobilized on AuNs which were appended on the graphite (Gr) electrode via chemisorption onto thiol-functionalized graphene oxide (GO-SH). This Gr/GO-SH/AuNs/ChOx biosensor has been characterized using cyclic voltammetry (CV), electrochemical impedance spectroscopy and chronoamperometry. CV results indicated a direct electron transfer between the enzyme and the electrode surface. A new potentiostat intermitant titration technique (PITT) has been studied to determine the diffusion coefficient and maxima potential value. The proposed biosensor showed rapid response, high sensitivity, wide linear range and low detection limit. Furthermore, our AuNs modified electrode showed excellent selectivity, repeatability, reproducibility and long term stability. The proposed electrode has also been used successfully to determine cholesterol in serum samples.

Facile synthesis and characterization of thiol-functionalized graphene oxide as effective adsorbent for Hg(II)

In this work, we report the synthesized and characterization of mercaptobenzothiazole (MBT) functionalized graphene oxide (GO) as a novel adsorbent material for the adsorption of Hg(II). This adsorption process could be realized with GO and MBT acting as host-guest in the first instance followed by the subsequent complexation of Hg(II) with MBT, the soft–soft interaction between Hg(II) & sulphur enhances the effective complexation. The prepared graphene-based adsorbent was characterised by X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, Powder-X-ray diffraction (Powder-XRD), Transmission electron microscopes (TEM), Fourier transform infrared spectroscopy (FT-IR), UV–vis spectroscopy, scanning electron microscopes (SEM) and energy-dispersive X-ray analysis (EDX). The capability of ICP-MS for Hg(II) adsorption was extensively studied under different optimal parameters, the developed method was successfully applied to mercury adsorption from water samples.

Removal of Pb(II) ion from aqueous solution by graphene oxide and functionalized graphene oxide-thiol: effect of cysteamine concentration on the bonding constant

Efficient adsorbent graphene oxide (GO) and its derivative, i.e., thiol-functionalized graphene oxide (GO-SH), was used for the removal of noxious Pb(II) ion from the aqueous phase. Different amounts, i.e., 60, 80, and 100 mg of cysteamine, were used as functionalizing agent to functionalize the GO with thiol group; hence, three different nanocomposites, i.e., GO-SH1, GO-SH2, and GO-SH3 were prepared from the different amount of the cysteamine. The developed nanocomposites were characterized using various analytical techniques such as Fourier transform infrared spectroscopy, scanning electron microscopy, and X-ray diffraction analysis. The whole removal and adsorption process was well illustrated and investigated. The impact of influential factors including initial concentration, pH, contact time, temperature, and concentrations cysteamine on the adsorption properties of Pb(II) from aqueous solution was well elucidated and optimized. The obtained equilibrium results were inserted in various adsorption isotherm models such as Langmuir (liner types I, II, III, and IV), Freundlich, Temkin, Helsey, and Dubinin-Radushkevich isotherms, it was found that the Langmuir (type I) model demonstrated was well fitted and in good agreement with the maximum adsorption of Pb(II) ion from aqueous solution. Thermodynamic functions, such as ∆G°, ∆H°, and ∆S° were calculated and it reveals that the adsorption of Pb(II) ion on all the surfaces was spontaneous and endothermic in nature.

Monothiolation and Reduction of Graphene Oxide via One-Pot Synthesis: Hybrid Catalyst for Oxygen Reduction

The functionalization of graphene provides diverse possibilities to improve the handling of graphene and enable further chemical transformation on graphene. Graphene functionalized with mainly heteroatom-based functional groups to enhance its chemical and physical properties is intensively pursued but often resulted in grafting of the heteroatoms as various functional groups. Here, we show that graphene oxide can be functionalized with predominantly a single type of sulfur moiety and reduced simultaneously to form monothiol-functionalized graphene. The thiol-functionalized graphene shows a high electrical conductivity and heterogeneous electron transfer rate. Graphene is also embedded with a trace amount of manganese impurities originating from a prior graphite oxidation process, which facilitates the thiol-functionalized graphene to function as a hybrid electrocatalyst for oxygen reduction reactions in alkaline medium with an onset potential lower than for Pt/C. Further characterizations of the graphene are performed with X-ray photoelectron spectroscopy, scanning electron microscopy with energy-dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, Raman spectroscopy, and electrochemical impedance spectroscopy. This material contributes to the class of hybrids that are highly active electrocatalysts.

Photophysical and photoconductivity properties of thiol-functionalized graphene–CdSe QD composites

Graphene–semiconductor QD hybrid nanostructure materials have recently emerged as a new class of functional materials because of their potential applications in solar energy conversion, optoelectronic devices, sensing etc. Here, oleic acid-capped CdSe QDs are attached to –PhSH functionalized graphene by ligand exchange via bonding with the –SH group. The shifting of the G-band and D-band due to structural changes for the attachment of QD with graphene has been evaluated by using Raman spectroscopy. Steady state photoluminescence (PL) and time resolved fluorescence measurements have been employed to understand the electronic interactions between graphene and CdSe QDs. A time resolved fluorescence spectroscopic study has been used to understand the fluorescence dynamics of the photoexcitated CdSe QDs in the presence of graphene. It is evident that the electron transfer occurs from photoexcited QDs to graphene and the electron transfer rate is found to be 12.8 × 108 s−1 for 3.8 nm CdSe QDs. Photoconductivity properties of the graphene–QD device under illumination have been examined and it is to be noted that 2–3 fold increase in the photocurrent is found in this composite device in presence of 1.5 AM solar simulated light. The enhancement of the photocurrent in this hybrid device is found to be suitable for potential applications in optoelectronic and solar cell systems.

Functionalized graphene oxide as a nanocatalyst in dephosphorylation reactions: pursuing artificial enzymes.

The present study reports for the first time the use of a thiol-functionalized graphene oxide nanocatalyst with impressive activity (>10(5)-fold) in dephosphorylation reactions. The innovative and recyclable nanocatalyst has potential in designing artificial enzymes with targeted multifunctionalities and in detoxification of organophosphorus agents.

Hybrid materials of platinum nanoparticles and thiol-functionalized graphene derivatives

Hybrid materials of platinum nanoparticles (Pt-NP) and thiol-functionalized thermally reduced graphite oxide (TRGO-SH), were synthesized by thermal decomposition of the organometallic precursor methylcyclopentadienyl-trimethylplatinum(IV) in dispersions of TRGO-SH in the ionic liquid 1-n-butyl-3-methyl-imidazolium tetrafluoroborate under microwave-assisted heating conditions. For the kinetic stabilization of Pt-NPs on TRGO-SH no additional donor ligands were necessary. The ionic liquid acts as separator of the TRGO-SH graphene sheets and as kinetic stabilizing template in the Pt-nanoparticle formation process. Thiol-functionalization of thermally reduced graphite oxide was carried out using three different synthetic procedures: (1) ring opening of propylene sulfide; (2) xanthate grafting and reduction to thiol; (3) reduction, thioesterfication under Mitsunobu conditions and ester hydrolysis. These three different TRGO-SH materials (1), (2) and (3) had different sulfur contents (1.2, 2.5 and 14wt.%, respectively) and were used as support materials for platinum nanoparticles. The loading of Pt-NPs on TRGO-SH (1), (2) and (3) was 3.2, 3.5 and 8.8wt.% with particle diameters determined from transmission electron microscopy of (9±4), (2.5±0.9) and (5±2) nm, respectively.

Immobilizing CdS quantum dots and dendritic Pt nanocrystals on thiolated graphene nanosheets toward highly efficient photocatalytic H2 evolution

We report the development of a highly efficient photocatalytic system by immobilizing high-quality CdS quantum dots and dendritic Pt nanocrystals on thiol-functionalized graphene substrates. We have demonstrated that the use of QDs with compact sizes leads to a dramatically enhanced performance in comparison with their bulk counterparts. Our design allows for systematic examination of the impact of QD sizes and the loading, morphology, and surface coating of the Pt nanocrystal cocatalyst on the H2 evolution activity. It was found that the CdS-Pt binary system has a high photocatalytic efficiency of 1.37 mmol h(-1) for visible light driven H2 evolution, and there was a 30% improvement by introducing the thiolated reduced graphene oxide to form the three-component CdS-Pt-Gcys nanocomposites. The highest H2 evolution rate of 2.15 mmol h(-1) (λ ≥ 420 nm) with a QE of 50.7% was achieved by further photo-annealing of the CdS-Pt-Gcys nanocomposites prior to the photocatalytic reaction.

The Effect of Surface Functionalization on the Immobilization of Gold Nanoparticles on Graphene Sheets

In our study, graphene oxide is synthesized by Hummers method. And then, carboxylic acid functionalized graphene (graphene-COOH), thiol-functionalized graphene (graphene-SH), and highly dispersive graphene are prepared by chemical modification of respective groups on the graphene surface. Furthermore, we explore a solution-based approach to prepare three differently functionalized graphene-gold composites by one-step chemical reduction ofAuCl4 -ions in respective functionalized graphene suspensions, where the gold nanoparticles are deposited on the functionalized graphene surface during their synthesis process. In addition, we compare the influence of surface functionalization on the growth of gold nanoparticles on graphene surface. Transmission electron morphology (TEM) and ultraviolet-visible (UV-Vis) spectroscopy are employed to study the effect of surface functionalities on AuNPs distribution onto the graphene surface and demonstrate the successful immobilization of AuNPs on graphene surface.