Showing papers on "Graphite published in 2011"

Carbon-based Supercapacitors Produced by Activation of Graphene

Abstract: Supercapacitors, also called ultracapacitors or electrochemical capacitors, store electrical charge on high-surface-area conducting materials. Their widespread use is limited by their low energy storage density and relatively high effective series resistance. Using chemical activation of exfoliated graphite oxide, we synthesized a porous carbon with a Brunauer-Emmett-Teller surface area of up to 3100 square meters per gram, a high electrical conductivity, and a low oxygen and hydrogen content. This sp 2 -bonded carbon has a continuous three-dimensional network of highly curved, atom-thick walls that form primarily 0.6- to 5-nanometer-width pores. Two-electrode supercapacitor cells constructed with this carbon yielded high values of gravimetric capacitance and energy density with organic and ionic liquid electrolytes. The processes used to make this carbon are readily scalable to industrial levels.

Antibacterial Activity of Graphite, Graphite Oxide, Graphene Oxide, and Reduced Graphene Oxide: Membrane and Oxidative Stress

Abstract: Health and environmental impacts of graphene-based materials need to be thoroughly evaluated before their potential applications. Graphene has strong cytotoxicity toward bacteria. To better understand its antimicrobial mechanism, we compared the antibacterial activity of four types of graphene-based materials (graphite (Gt), graphite oxide (GtO), graphene oxide (GO), and reduced graphene oxide (rGO)) toward a bacterial model—Escherichia coli. Under similar concentration and incubation conditions, GO dispersion shows the highest antibacterial activity, sequentially followed by rGO, Gt, and GtO. Scanning electron microscope (SEM) and dynamic light scattering analyses show that GO aggregates have the smallest average size among the four types of materials. SEM images display that the direct contacts with graphene nanosheets disrupt cell membrane. No superoxide anion (O2•–) induced reactive oxygen species (ROS) production is detected. However, the four types of materials can oxidize glutathione, which serves ...

High-Quality Thin Graphene Films from Fast Electrochemical Exfoliation

Abstract: Flexible and ultratransparent conductors based on graphene sheets have been considered as one promising candidate for replacing currently used indium tin oxide films that are unlikely to satisfy future needs due to their increasing cost and losses in conductivity on bending. Here we demonstrate a simple and fast electrochemical method to exfoliate graphite into thin graphene sheets, mainly AB-stacked bilayered graphene with a large lateral size (several to several tens of micrometers). The electrical properties of these exfoliated sheets are readily superior to commonly used reduced graphene oxide, which preparation typically requires many steps including oxidation of graphite and high temperature reduction. These graphene sheets dissolve in dimethyl formamide (DMF), and they can self-aggregate at air-DMF interfaces after adding water as an antisolvent due to their strong surface hydrophobicity. Interestingly, the continuous films obtained exhibit ultratransparency (∼96% transmittance), and their sheet resistance is <1k Ω/sq after a simple HNO3 treatment, superior to those based on reduced graphene oxide or graphene sheets by other exfoliation methods. Raman and STM characterizations corroborate that the graphene sheets exfoliated by our electrochemical method preserve the intrinsic structure of graphene.

Thermal Properties of Isotopically Engineered Graphene

Abstract: was shown to be substantially different in two-dimensional (2D) crystals, such as graphene, than in three-dimensional (3D) graphite [7-10]. Here, we report the first experimental study of the isotope effects on the thermal properties of graphene. Isotopically modified graphene containing various percentages of

High-yield synthesis of few-layer graphene flakes through electrochemical expansion of graphite in propylene carbonate electrolyte

Abstract: High-yield production of few-layer graphene flakes from graphite is important for the scalable synthesis and industrial application of graphene. However, high-yield exfoliation of graphite to form graphene sheets without using any oxidation process or super-strong acid is challenging. Here we demonstrate a solution route inspired by the lithium rechargeable battery for the high-yield (>70%) exfoliation of graphite into highly conductive few-layer graphene flakes (average thickness <5 layers). A negative graphite electrode can be electrochemically charged and expanded in an electrolyte of Li salts and organic solvents under high current density and exfoliated efficiently into few-layer graphene sheets with the aid of sonication. The dispersible graphene can be ink-brushed to form highly conformal coatings of conductive films (15 ohm/square at a graphene loading of <1 mg/cm2) on commercial paper.

Lithium Diffusion in Graphitic Carbon

Abstract: Graphitic carbon is currently considered the state-of-the-art material for the negative electrode in lithium-ion cells, mainly due to its high reversibility and low operating potential. However, carbon anodes exhibit mediocre charge/discharge rate performance, which contributes to severe transport-induced surface-structural damage upon prolonged cycling, and limits the lifetime of the cell. Lithium bulk diffusion in graphitic carbon is not yet completely understood, partly due to the complexity of measuring bulk transport properties in finite-sized, non-isotropic particles. To solve this problem for graphite, we use the Devanathan-Stachurski electrochemical methodology combined with ab-initio computations to deconvolute, and quantify the mechanism of lithium-ion diffusion in highly oriented pyrolytic graphite (HOPG). The results reveal inherent high lithium-ion diffusivity in the direction parallel to the graphene plane (ca. 10^-7 - 10^-6 cm2 s-1), as compared to sluggish lithium-ion transport along grain boundaries (ca. 10^-11 cm^2 s^-1), indicating the possibility of rational design of carbonaceous materials and composite electrodes with very high rate capability.

Chemical vapor deposition-grown graphene: the thinnest solid lubricant.

Abstract: As an atomically thin material with low surface energy, graphene is an excellent candidate for reducing adhesion and friction when coated on various surfaces. Here, we demonstrate the superior adhesion and frictional characteristics of graphene films which were grown on Cu and Ni metal catalysts by chemical vapor deposition and transferred onto the SiO2/Si substrate. The graphene films effectively reduced the adhesion and friction forces, and multilayer graphene films that were a few nanometers thick had low coefficients of friction comparable to that of bulk graphite.

The Shear Mode of Multi-Layer Graphene

Abstract: We uncover the interlayer shear mode of multi-layer graphene samples, ranging from bilayer-graphene (BLG) to bulk graphite, and show that the corresponding Raman peak measures the interlayer coupling. This peak scales from~43cm-1 in bulk graphite to~31cm-1 in BLG. Its low energy makes it a probe of near-Dirac point quasi-particles, with a Breit-Wigner-Fano lineshape due to resonance with electronic transitions. Similar shear modes are expected in all layered materials, providing a direct probe of interlayer interactions

Dual Path Mechanism in the Thermal Reduction of Graphene Oxide

Abstract: Graphene is easily produced by thermally reducing graphene oxide However, defect formation in the C network during deoxygenation compromises the charge carrier mobility in the reduced material Understanding the mechanisms of the thermal reactions is essential for defining alternative routes able to limit the density of defects generated by carbon evolution Here, we identify a dual path mechanism in the thermal reduction of graphene oxide driven by the oxygen coverage: at low surface density, the O atoms adsorbed as epoxy groups evolve as O(2) leaving the C network unmodified At higher coverage, the formation of other O-containing species opens competing reaction channels, which consume the C backbone We combined spectroscopic tools and ab initio calculations to probe the species residing on the surface and those released in the gas phase during heating and to identify reaction pathways and rate-limiting steps Our results illuminate the current puzzling scenario of the low temperature gasification of graphene oxide

Bi- and trilayer graphene solutions.

Abstract: Bilayer and trilayer graphene with controlled stacking is emerging as one of the most promising candidates for post-silicon nanoelectronics. However, it is not yet possible to produce large quantities of bilayer or trilayer graphene with controlled stacking, as is required for many applications. Here, we demonstrate a solution-phase technique for the production of large-area, bilayer or trilayer graphene from graphite, with controlled stacking. The ionic compounds iodine chloride (ICl) or iodine bromide (IBr) intercalate the graphite starting material at every second or third layer, creating second- or third-stage controlled graphite intercolation compounds, respectively. The resulting solution dispersions are specifically enriched with bilayer or trilayer graphene, respectively. Because the process requires only mild sonication, it produces graphene flakes with areas as large as 50 µm(2). Moreover, the electronic properties of the flakes are superior to those achieved with other solution-based methods; for example, unannealed samples have resistivities as low as ∼1 kΩ and hole mobilities as high as ∼400 cm(2) V(-1) s(-1). The solution-based process is expected to allow high-throughput production, functionalization, and the transfer of samples to arbitrary substrates.

High concentration few-layer graphene sheets obtained by liquid phase exfoliation of graphite in ionic liquid

Abstract: In the present work, the use of a commercial ionic liquid as a convenient solvent medium for graphite exfoliation in mild and easy conditions without any chemical modification is presented. To confirm the presence of few layer graphene, its dispersion, which exhibits Tyndall effect, was characterized by Raman and UV spectroscopies, and atomic force and field emission electron microscopies. It is noteworthy that, by gravimetric analysis, a graphene concentration as high as 5.33 mg ml−1 was determined, which is the highest value reported so far in any solvent.

Simple room-temperature preparation of high-yield large-area graphene oxide

Abstract: Graphene has attracted much attention from researchers due to its interesting mechanical, electrochemical, and electronic properties. It has many potential applications such as polymer filler, sensor, energy conversion, and energy storage devices. Graphene-based nanocomposites are under an intense spotlight amongst researchers. A large amount of graphene is required for preparation of such samples. Lately, graphene-based materials have been the target for fundamental life science investigations. Despite graphene being a much sought-after raw material, the drawbacks in the preparation of graphene are that it is a challenge amongst researchers to produce this material in a scalable quantity and that there is a concern about its safety. Thus, a simple and efficient method for the preparation of graphene oxide (GO) is greatly desired to address these problems. In this work, one-pot chemical oxidation of graphite was carried out at room temperature for the preparation of large-area GO with ∼100% conversion. This high-conversion preparation of large-area GO was achieved using a simplified Hummer's method from large graphite flakes (an average flake size of 500 µm). It was found that a high degree of oxidation of graphite could be realized by stirring graphite in a mixture of acids and potassium permanganate, resulting in GO with large lateral dimension and area, which could reach up to 120 µm and ∼8000 µm 2 , respectively. The simplified Hummer's method provides a

Mesoporous Carbon for Capacitive Deionization of Saline Water

Abstract: Self-assembled mesoporous carbon (MC) materials have been synthesized and tested for application in capacitive deionization (CDI) of saline water. MC was prepared by self-assembly of a triblock copolymer with hydrogen-bonded chains via a phenolic resin, such as resorcinol or phloroglucinol in acidic conditions, followed by carbonization and, in some cases, activation by KOH. Carbon synthesized in this way was ground into powder, from which activated MC sheets were produced. In a variation of this process, after the reaction of triblock copolymer with resorcinol or phloroglucinol, the gel that was formed was used to coat a graphite plate and then carbonized. The coated graphite plate in this case was not activated and was tested to serve as current collector during the CDI process. The performance of these MC materials was compared to that of carbon aerogel for salt concentrations ranging between 1000 ppm and 35,000 ppm. Resorcinol-based MC removed up to 15.2 mg salt per gram of carbon, while carbon aerogel removed 5.8 mg salt per gram of carbon. Phloroglucinol-based MC-coated graphite exhibited the highest ion removal capacity at 21 mg of salt per gram of carbon for 35,000 ppm salt concentration.

Glucose-assisted growth of MoS2 nanosheets on CNT backbone for improved lithium storage properties.

Abstract: As a typical layered inorganic material, molybdenum disulfide (MoS2) has a similar structure to graphite. In the crystal structure of MoS2, each Mo(IV) sits in the center of a triangular prism, and is bound to six S atoms. Each S atom is connected to three Mo centers. In this way, the triangular prisms are interconnected to give a layered structure, wherein the Mo atoms are sandwiched between two layers of S atoms. Because of the weak van der Waals interactions between the sheets, MoS2 has a low friction coefficient; this gives rise to its superior lubricating properties. It has also been found attractive in many other application, including catalysts and transistors. Additionally, the layered structure of MoS2 enables easy intercalation of metal ions, such as Li or Mg . Many different MoS2 nanostructures, such as nanoflakes, nanotubes and nanoflowers, have been reported so far as anode materials for lithium ion batteries (LIBs). Although some of them show relatively high capacities of up to 1000 mAhg , the unsatisfactory cycling stability hinders their practical application as anode materials of LIBs. Some methods have been proposed to improve the cycling performance of MoS2, for example, construction of composite materials of MoS2 and conductive carbonaceous materials, like amorphous carbon, carbon nanotubes (CNTs), or graphene. For example, Li et al. reported a hybrid material of CNTs coated with several layers of MoS2. [15] When tested for lithium storage capabilities, the CNT@MoS2 hybrid structure shows a relatively good cyclic capacity retention with a reversible capacity of only up to 400 mAhg , probably due to the low mass fraction of MoS2 in the composite. Thus, obtaining a high content of MoS2 in the CNT@MoS2 is important for a better lithium storage capability. Many CNT-based hybrid structures have been prepared for different applications. 17] Herein, we report a simple glucose-assisted hydrothermal method to directly grow MoS2 nanosheets (NSs) on the CNT backbone (CNT@MoS2 NSs). The content of MoS2 in the hybrid structure is greatly increased because the shell is composed of sheet-like subunits. At the same time, the large surface area provided by this unique hierarchical structure can perhaps help to store more lithium, and the void space between these sheet-like subunits can buffer the volume change during the charge/ discharge processes, and lead to improved cyclic capacity retention. Furthermore, the carbon derived from glucose could ensure an excellent contact between the CNT backbone and the shell of MoS2 NSs, and give rise to a good conducting network. As expected, in comparison with pure MoS2 flakes, these CNT@MoS2 NS nanocomposites show enhanced lithium storage properties with better cyclic capacity retention and a higher reversible capacity. Figure 1 shows the morphology of the as-prepared CNT@MoS2 NSs. From the scanning electron microscopy

Synthesis and Characterization of Large-Area Graphene and Graphite Films on Commercial Cu–Ni Alloy Foils

Abstract: Controlling the thickness and uniformity during growth of multilayer graphene is an important goal. Here we report the synthesis of large-area monolayer and multilayer, particularly bilayer, graphene films on Cu–Ni alloy foils by chemical vapor deposition with methane and hydrogen gas as precursors. The dependence of the initial stages of graphene growth rate on the substrate grain orientation was observed for the first time by electron backscattered diffraction and scanning electron microscopy. The thickness and quality of the graphene and graphite films obtained on such Cu–Ni alloy foils could be controlled by varying the deposition temperature and cooling rate and were studied by optical microscopy, scanning electron microscopy, atomic force microscopy, and micro-Raman imaging spectroscopy. The optical and electrical properties of the graphene and graphite films were studied as a function of thickness.

Dye Adsorption on Layered Graphite Oxide

Abstract: Graphite oxide (GO) was prepared by a modified Hummers−Offeman method and was tested as an adsorbent for the removal of dyes in aqueous solution. The structure of GO was characterized by N2 adsorption, X-ray diffraction (XRD), and Fourier transform infrared (FT-IR) spectroscopy. It is found that GO does not show a significant change in surface area, but the layered graphene structure was expanded, and several surface oxygen functional groups were formed, which play a significant role in adsorption. The amount of the dyes, methylene blue and malachite green, adsorbed on the GO was much higher than that on graphite, and the adsorption capacity based on the Langmuir isotherm is (351 and 248) mg·g−1, respectively, much higher than activated carbon. The adsorption mechanism was proposed as electrostatic attraction.

Polyelectrolyte-induced reduction of exfoliated graphite oxide: a facile route to synthesis of soluble graphene nanosheets.

Abstract: Here we report that poly(diallyldimethylammonium chloride) (PDDA) acts as both a reducing agent and a stabilizer to prepare soluble graphene nanosheets from graphite oxide. The results of transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, atomic force microscopy, and Fourier transform infrared indicated that graphite oxide was successfully reduced to graphene nanosheets which exhibited single-layer structure and high dispersion in various solvents. The reaction mechanism for PDDA-induced reduction of exfoliated graphite oxide was proposed. Furthermore, PDDA facilitated the in situ growth of highly dispersed Pt nanoparticles on the surface of graphene nanosheets to form Pt/graphene nanocomposites, which exhibited excellent catalytic activity toward formic acid oxidation. This work presents a facile and environmentally friendly approach to the synthesis of graphene nanosheets and opens up a new possibility for preparing graphene and graphene-based nanomaterials for large-...

In Situ Polymerization of Graphene, Graphite Oxide, and Functionalized Graphite Oxide into Epoxy Resin and Comparison Study of On-the-Flame Behavior

Abstract: Starting from expandable graphite (EG), graphene, graphite oxide (GO), and organic phosphate functionalized graphite oxides (FGO) were prepared and incorporated into epoxy resin (EP) matrix via in situ polymerization to prepare EP based composites. The structure of the composites was characterized by transmission electron microscopy to show good dispersion without large aggregates. The thermal behavior investigated by thermogravimetric analysis indicated the EP/graphene composites show the highest onset temperature and maximum weight loss temperature compared with those added with GO and FGO. The flame retardant properties investigated by micro combustion calorimeter illustrate that both EP/graphene and EP/FGO composites perform better than EP/GO composites in flame retardant properties with a maximum reduction of 23.7% in peak-heat release rate when containing 5 wt % FGO and a maximum reduction of 43.9% at 5 wt % loading of graphene. This study represents a new approach to prepare functionalized GO with ...

LiMn1−xFexPO4 Nanorods Grown on Graphene Sheets for Ultrahigh‐Rate‐Performance Lithium Ion Batteries

Abstract: Olivine-type lithium transition-metal phosphates LiMPO4 (M=Fe, Mn, Co, or Ni) have been intensively investigated as promising cathode materials for rechargeable lithium ion batteries (LIBs) owing to their high capacity, excellent cycle life, thermal stability, environmental benignity, and low cost. However, the inherently low ionic and electrical conductivities of LiMPO4 seriously limit Li + insertion and extraction and charge transport rates in these materials. In recent years, these obstacles have been overcome for LiFePO4 by reducing the size of LiFePO4 particles to the nanoscale and applying conductive surface coatings such as carbon, which leads to commercially viable LiFePO4 cathode materials. Compared to LiFePO4, LiMnPO4 is an attractive cathode material owing to its higher Li intercalation potential of 4.1 V versus Li/Li (3.4 V for LiFePO4), providing about 20% higher energy density than LiFePO4 for LIBs. [14–19] Importantly, the 4.1 V intercalation potential of LiMnPO4 is compatible with most of the currently used liquid electrolytes. However, the electrical conductivity of LiMnPO4 is lower than the already insulating LiFePO4 by five orders of magnitude, making it challenging to achieve high capacity at high rates for LiMnPO4 using methods developed for LiFePO4. [14–19] Doping LiMnPO4 with Fe has been pursued to enhance conductivity and stability of the material in its charged form. Recently, Martha et al. have obtained improved capacity and rate performance for carbon-coated LiMn0.8Fe0.2PO4 nanoparticles synthesized by a high-temperature solid-state reaction. Graphene is an ideal substrate for growing and anchoring insulating materials for energy storage applications because of its high conductivity, light weight, high mechanical strength, and structural flexibility. The electrochemical performance of various electrode materials can be significantly boosted by rendering them conducting with graphene sheets. Recent work has shown improved specific capacities and rate capabilities of simple oxide nanomaterials (Mn3O4, Co3O4, and Fe3O4) grown on graphene as LIB anode materials. However, it remains a challenge to grow nanocrystals on graphene sheets in solution for materials with more sophisticated compositions and structures, such as LiMn1 xFexPO4, which is a promising but extremely insulating cathode material for LIBs. Herein we present a two-step approach for synthesis of LiMn1 xFexPO4 nanorods on reduced graphene oxide sheets stably suspended in solution. Fe-doped Mn3O4 nanoparticles were first selectively grown onto graphene oxide by controlled hydrolysis. The oxide nanoparticle precursors then reacted solvothermally with Li and phosphate ions and were transformed into LiMn1 xFexPO4 on the surface of reduced graphene oxide sheets. With a total content of 26 wt% conductive carbon, the resulting hybrid of nanorods and graphene showed high specific capacity and unprecedentedly high power rate for LiMn1 xFexPO4 type of cathode materials. Stable capacities of 132 mAhg 1 and 107 mAhg 1 were obtained at high discharge rates of 20C and 50C, which is 85% and 70% of the capacity at C/2 (155 mAhg ), respectively. This affords LIBs with both high energy and high power densities. This is also the first synthesis of LiMn0.75Fe0.25PO4 nanorods that have an ideal crystal shape and morphology for fast Li diffusion along the radial [010] direction of the nanorods. Figure 1 shows our two-step solution-phase reaction for the synthesis LiMn0.75Fe0.25PO4 nanorods on reduced graphene oxide (for experimental details, see the Supporting Information). The first step was to selectively grow oxide nanoparticles at 80 8C on mildly oxidized graphene oxide (mGO) stably suspended in a solution. Controlling the hydrolysis rate of Mn(OAc)2 and Fe(NO3)3 by adjusting the H2O/N,N-dimethylformamide (DMF) solvent ratio and the reaction temperature afforded selective and uniform coating of circa 10 nm nanoparticles of Fe-doped Mn3O4 (Supporting Information, Figure S1a; X-ray diffraction data in Figure S1b) on the mGO sheets without free growth of nanoparticles in solution. Importantly, our mGO was made by a modified Hummers method (Supporting Information), with which a sixfold lower concentration of KMnO4 oxidizer was used to afford milder oxidation of graphite. The resulting mGO sheets contained a lower oxygen content than Hummers GO (ca. 15% vs. ca. 30% measured by X-ray photoelectron spectroscopy (XPS) and Auger spectroscopy) and showed higher electrical conductivity when chemically reduced than [*] H. Wang, Y. Liang, H. Sanchez Casalongue, Y. Li, G. Hong, Prof. H. Dai Department of Chemistry Stanford University, Stanford, CA 94305 (USA) E-mail: hdai@stanford.edu Y. Yang, L. Cui, Prof. Y. Cui Department of Materials Science and Engineering Stanford University, Stanford, CA 94305 (USA) E-mail: yicui@stanford.edu [] These authors contributed equally to this work.

Nucleation mechanism for the direct graphite-to-diamond phase transition

Abstract: Graphite remains stable at pressures higher than those of its equilibrium coexistence with diamond This has proved hard to explain, owing to the difficulty in simulating the transition with accuracy Ab initio calculations using a trained neural-network potential now show that the stability of graphite and the direct transformation of graphite to diamond can be accounted for by a nucleation mechanism

Low-temperature phase transformation from graphite to sp3 orthorhombic carbon.

Abstract: We identify by ab initio calculations an orthorhombic carbon polymorph in Pnma symmetry that has the lowest enthalpy among proposed cold-compressed graphite phases. This new phase contains alternating zigzag and armchair buckled carbon sheets transformed via a one-layer by three-layer slip mechanism. It has a wide indirect band gap and a large bulk modulus that are comparable to those of diamond. Its simulated x-ray diffraction pattern best matches the experimental data. Pressure plays a key role in lowering the kinetic barrier during the phase conversion process. These results provide a comprehensive understanding and an excellent account for experimental findings.

Gold Nanoclusters and Graphene Nanocomposites for Drug Delivery and Imaging of Cancer Cells

Abstract: Gold nanoclusters (GNCs) have attracted wide attention owing to their outstanding surface and physical properties (for example, near-infrared photoluminescence, optical chirality, and ferromagnetism), which has led to a wide range of applications, such as for single-molecule photonics, sensing, and biological labeling. In contrast to organic dyes and quantum dots, GNCs do not contain chemical functions and toxic heavy metals. Their near-infrared range of emission avoids interference from many biological moieties, making GNCs ideal for biological assays and cell imaging so that they may become a powerful alternative to usual fluorescence labels. On the other hand, two dimensional graphene has attracted considerable interest owing to its long-range p conjugation, yielding extraordinary thermal, mechanical, and electrical properties. To date, the chemistry of graphene that has been reported mainly concerns the chemistry of graphene oxide (GO), which has chemically reactive oxygen-containing groups, including carboxylic acid groups at the edges of GO and epoxy and hydroxy groups on the basal planes. Because electrical conductivity, a large specific Brunauer–Emmett–Teller surface area, and high fracture strength can be recovered by restoring the p network, one of the most important reactions of GO is its reduction. Previous studies have established that graphene, including GO and its reduced form, reduced graphene oxide (RGO), is biocompatible and is a perfect support for a variety of metal and metal oxide nanoparticles, such as Pt, Au, TiO2, [9] fluorescent molecules, and drugs with potential biochemical applications. Functionalized graphene sheets are thus prone to act as drug delivery platforms, while their nearinfrared thermal properties make them attractive multimodal cancer therapeutic agents. Furthermore, RGO could also allow a facile attachment of many molecular drugs and nanomaterials. RGO has been frequently modified by noncovalent physisorption of polymers, small aromatic molecules, and metal nanoparticles with higher electron affinity, such as gold, onto their basal planes by p–p stacking, cation–p, or van der Waals interactions. For GNC-RGO nanocomposites, it may not only offer new and efficient entries in the current search for multimodal therapeutic materials that are prone to targeting/detecting and treating specifically altered tissues, but also offer attractive alternatives to existing cancer therapeutic techniques. Herein, we explore the biological properties of newly prepared GNC-RGO nanocomposites. This material could cause inhibition of HepG2 cells at high concentration, but more interestingly for oncotherapy it could carry anticancer agents such as doxorubicin (DOX) inside the cells while leading to some synergy in inducing karyopyknosis. It is observed that GNCs anchored on RGO retain their nearinfrared fluorescent property so that Raman spectroscopy could be used to investigate the performance of DOX-loaded GNC-RGO nanocomposites against hepatocarcinoma and provide important mechanistic clues about their interactions with proteins and DNA. GNCs were prepared in the organic phase following a conventional Brust–Schiffrin procedure and transferred into an aqueous phase. Simple mixing of the dodecanethiolCTAB-capped GNCs with RGO in aqueous solution followed by separation afforded water-soluble GNC-RGO nanocomposites in excellent yields. TEM analysis (Figure 1a) established that 95% of the water-soluble GNCs ranged between 2–3 nm in diameter with a distribution peak at 2.5 nm. They maintained their size distribution and morphology upon attachment to RGO (Figure 1b). HRTEM (Figure 1b, inset) showed that the GNCs kept their interplanar Au–Au spacing at 0.215 nm after attachment onto RGO. Though common gold nanoparticle sols exhibit a surface plasmon band (SPB), creating a broad absorption band in the visible region around 520 nm and thus their characteristic deep-red color, the color of GNCs and GNC-RGO was faint, in agreement with the fact that no obvious UV/Vis absorbance could be observed in Figure 1c. It is known that Au nanoparticles less than 3 nm in size do not exhibit the surface plasmon resonance characteristic peak at around 520 nm. This result is in good agreement with our observation (Figure 1 c) in which the absorption originating [*] C. Wang, J. Li, Dr. H. Jiang, Prof. X.-M. Wang State Key Lab of Bioelectronics (Chien-Shiung Wu Laboratory) Southeast University, No. 2 Sipailou, Nanjing 210096 (China) E-mail: xuewang@seu.edu.cn