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Growth morphology of carbon clusters deposited on different substrates were investigated by theoretical and experimental approach. For theoretical approach, molecular dynamics was employed to evaluate an adsorptive stability of different size of carbon clusters placed on different substrates. The adsorptive stability was estimated by the difference of total energy of supercell designed as carbon cluster placed on a certain crystal plane of substrate. Among the simulations of this study, carbon cluster flatly settled down on the surface of SrTiO$$_{3}$$ 3 (001). The result was experimentally verified with layer by layer growth of graphene by pulsed laser deposition in carbon dioxide atmosphere. The absorptive stability can be useful reference for screening substrate for any target material other than graphene.

Industrial scale manufacturing with tunable properties of graphene nano-sheets has been a practical concern in many applications. This study focuses on, a physical electro-chemistry approach for the synthesis of few-layer graphene nano-sheets (FLGNSs) in a scalable manner. The intercalates are bias-driven anions towards the working electrode of bulk pyrolytic graphite sheet followed by their exfoliations as FLGNSs. In-situ electrochemical studies confirm a higher rate of exfoliation with an increase in the concentration of intercalates. Based on colloidal conductivity and particle size analyses, the degree of crystallinity and effect of variation in intercalates is explored. Rate of oxidation, defects, morphological variation, and number of layers with variation of intercalate concentration have been studied by XRD, Raman spectroscopy, FTIR, UV–Vis spectroscopy, XPS, and electron microscope based analyses. Cost-effectiveness of the electrochemical process in producing FLGNSs is assessed by considering cost of raw materials used in this laboratory process. Schematics of Industrial scalable process for manufacturing FLGNSs.

The study emphasizes on the scalable production and comparison of few layered graphene nanosheets (FLGNSs). The FLGNSs have been electrochemically synthesized by anionic intercalation from three different acids of 1 M of H2SO4 (S1), 1-M HClO4 (C1), and 1-M HNO3 (N1). The size distribution and stability of the as-prepared FLGNSs colloidal have been analyzed thoroughly. A yield of around 50 % was found irrespective of experimental condition. A mixed phase of graphene and its oxide form has been confirmed X-ray diffraction patterns. C1- and N1-conditioned FLGNSs had higher oxygenation as compared to S1, as confirmed by X-ray photoelectron spectroscopy (XPS) analysis. The disorderness in the FLGNSs has been analyzed by Raman spectra. The aromaticity, surface hydroxylation, and oxygenation of the as-synthesized FLGNSs due to electrochemical reactions have been confirmed by Fourier transform infrared spectroscopy. The UV-visible spectra of FLGNSs colloidal show the electronic transition of π-π* as well as n-π*. From morphological studies, the layered and crumpled edges of the exfoliated FLGNSs have been revealed. Again, from the probe conductivity analysis, the measured conductivity of the dispersed sulfate-, perchlorate-, and nitrate-intercalated FLGNSs has been found with a decreasing trend from 1.652, 0.315, to 0.300 mS/cm for S1, C1, and N1 conditions, respectively, due to increasing of oxygen endowment in the graphene sheets. Detailed supercapacitor investigations demonstrated that the S1-conditioned FLGNSs show enhanced supercapacitor performance than C1 and N1. It possesses a maximum energy density of 20 Wh kg−1 and a maximum power density of 2.5 kW kg−1.

In this study, we synthesized new 0.01–2 μm graphene nanosheet/MnO2/WO3 (G/MnO2/WO3) architectures through an electrochemically induced cathodic plasma process in a single batch at a lower temperature (70 °C) and for a shorter time (2 h) than those required for the syntheses of similar structures when using a hydrothermal method. We first obtained 0.01–1 μm leaf-like graphene (G) nanosheets, then 0.1–0.3 μm long and approximately 10 nm diameter petiole-like MnO2 nanowires on the G nanosheets, and finally 0.20–2.0 μm petal-like WO3 on MnO2/G — thereby forming the G/MnO2/WO3 architectures — as evidenced using scanning electron microscopy and transmission electron microscopy. We deciphered the step-wise reaction mechanism behind the formation of the G/MnO2/WO3 architectures during the plasma process. The high surface area of 291 m2 g−1 in the G/MnO2/WO3 architecture was contributed mainly by the G nanosheets, providing a suitable surface area for diffusion of the charge carriers during the charging and discharging process. As a result, an electrode incorporating the G/MnO2/WO3 architectures exhibited an excellent specific capacitance of 620 F g−1 — 45 and 200% higher than those of G/MnO2 (421 F g−1) and G (189 F g−1) electrodes, respectively — at a current density of 0.5 A g−1. Moreover, the G/MnO2/WO3–incorporated electrode exhibited good electrochemical cycling stability, with 90% capacitance retention over 5000 cycles at 1 A g−1. Such new G/MnO2/WO3 heterojunction structures, not only provide high-performance electrode applications, but also suggest a potential approach toward fabricating other heterojunction structures having high surface areas for energy storage applications.

Vertically aligned silicon nanowire arrays (SiNWs) have been synthesized by electroless metal deposition process. The fabricated SiNWs have an average diameter of 75 nm and 3.5–4.0 μm length, as confirmed from scanning electron microscopy. A characteristic asymmetric peak broadening at 520 cm −1 from Raman spectroscopy was obtained for the SiNWs as compared to the bulk silicon crystal due to phonon confinement. The as-prepared SiNWs exhibit good electron field-emission properties with turn-on field of about 8.26 V μm −1 at a current density of 4.9 μA cm −2 . The SiNWs was functionalized by coating with a thin gold metallic film for 60 s, and then used as bio-probe for the detection of bovine serum albumin (BSA) protein molecules. From the linear sweep voltammetry analysis, the Au coated SiNWs, exhibit linear response to the BSA analyte with increase in concentration. The minimum detection limit of the protein molecule was calculated of about 1.16 μM by the as-synthesized SiNWs probe.

The mechanism of electrochemical intercalation resulting in the expansion and exfoliation behavior of the pyrolytic graphite sheets is described. In this paper, an efficient and simple process of the intercalation of perchlorate anions from a simple protic solvent at various electrolytic concentrations using a two electrode system is reported. The intercalate concentration plays a major role in the as-prepared exfoliated few layered graphene nanosheets (FLGNSs). The in situ oxygenation and hydroxylation of the FLGNSs has been painstakingly analyzed using X-ray diffraction, thermogravimetric analysis, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, Raman spectroscopy and UV-visible spectroscopy. Furthermore, the nature of the exfoliated FLGNSs colloidal was determined using field emission scanning electron microscopy, transmission electron microscopy as well as dynamic light scattering techniques. From the various analytical results obtained, it is found that the synthesized GNSs consist of FLGNSs with surface oxygenation. The extent of the surface oxygenation was found to be increased with an increase in the concentration of the intercalate. The exfoliated colloidal graphene obtained at an optimum electrolytic condition shows a stable dispersion and the highest conductivity was ∼0.87 mS cm−1. Furthermore, the conductivity of the oven dried colloidal graphene on a fluoride treated glass slide was successfully used in a light emitting diode fabrication test.

The present study focuses on the intriguing enhancement in the mechanical properties of an epoxy-based composite structure resulting from the incorporation of in-house synthesized functionalized graphene nanosheets (f-GNSs) as nanofillers. The f-GNSs were obtained by anionic electrochemical intercalation and exfoliation with 2 M H2SO4, HClO4, and HNO3 protic electrolytes. The structural properties of the as-synthesized GNSs were analyzed by XRD and Raman spectroscopy. The (002) and (001) lattice planes of graphene and graphene oxide are observed at around 24.5° and 11° (2θ), respectively, in the XRD spectra. The characteristic peaks at around 1345, 1590, and 2700 cm-1 correspond to the D, G, and 2D bands of the GNSs in the Raman spectra. Quantification of the functional groups and sp2 contents in the GNSs were further analyzed by XPS. Morphological characterization of the f-GNSs reveals that the exfoliated carbon sheets consist of 2-8 layers. The composites are then fabricated by addition of these f-GNSs nanofillers, and the effect of the wt% of the nanofillers on the mechanical properties of the composites is analyzed with the three-point bend test and fractography analysis through interfacial morphological analysis. The addition of 0.1 wt% of nitric-acid-exfoliated f-GNSs nanofiller results in maximum increases of 42.6% and 28.2% in the flexural strengths of neat epoxy resin and glass fiber/epoxy polymer composite structures, respectively. Similarly, the moduli increase by 33.5% and 57.7% in the neat epoxy resin and glass fiber/epoxy polymer composite structures, respectively. The effect of epoxy/f-GNSs interfacial bonding in the composite structure was studied by DSC analysis.

Highly surface active super paramagnetic colloidal suspensions of nano crystalline ferrofluid have been synthesized through wet-chemical route. Entrapment of magnetic domains presented in the nano ferrofluid in a polymer matrix like poly vinyl alcohol film was accomplished by developing polymer composite film in between two magnetic poles by solvent casting method. Similarly poly vinyl alcohol-ferrofluid composite films were also developed in the absence of magnetic field. Atomic force microscopy image of nano-composite film makes it clear that the film developed in the absence of magnetic field possesses randomly oriented domains, whereas film developed with magnetic field shows well aligned flux lines. The characteristics and nature of forces acting between magnetic domains along the magnetic flux lines were explored from magnetic force microscopy imaging. The number of flux lines developed in the polymer matrix was observed to be directly proportional to applied external magnetic field. Approximate number of magnetic lines passing through unit area of composite film was evaluated from line profile data analysis of atomic force microscopy image. The particle sizes of the nanoparticles encapsulated in the polymer matrix were found to be in the range of 10–20 nm. Scanning electron microscopy micrographs confirm aggregation of ferrofluid particles of ribbon like morphology along the magnetic flux lines. Magnetic properties of the entrapped nanoparticles in polymer matrix film were analyzed using vibrating sample magnetometer at room temperature. The super paramagnetic nature and other magnetic properties were evaluated from the hysteresis loop.

Graphene nanosheets have attracted immense research interest among the materials science community from electronics to the biomedical field. Being the first member of two-dimensional nanomaterials family, discovered in 2004 followed by the Nobel Prize winning in 2010, it is now readily witnessing global industrial revolutions. The nanomaterial is bestowed with such unprecedented features that can be tangible to a wide spectrum of applications ranging from energy storage devices to sensor application. Enormous flattened surfaces, superior mechanical strength and flexibility, ballistic intrinsic carrier mobility, nearly transparent nature, high thermal conductivity and room-temperature ferromagnetic behavior are few of the extraordinary attributes of the monolayer of carbon nanosheets. In this comprehensive review, an attempt has been put forward to precisely revisit and represent the literature available on the fundamental properties of graphene nanomaterials. Also, the usage of its characteristic features in various applications as well as synthesis process has been briefly discussed.

The electron field emission (EFE) properties of vertically aligned arrays of silicon nanowires (SiNWs) grown from silicon substrate at different gold sputtering periods of 0[Formula: see text]s, 8[Formula: see text]s, 15[Formula: see text]s and 25[Formula: see text]s at a rate of 10[Formula: see text]nm/min by electroless metal deposition process were investigated. It has been observed that the transformation of silicon tips from irregular to highly dense and uniform cylindrical morphological nanostructures with an increase in Au sputtering periods. A significant enhancement in EFE properties of as-prepared arrays of SiNWs with the increase in Au sputtering periods is observed. The threshold fields for attaining current density of 0.1[Formula: see text]mA[Formula: see text][Formula: see text] were decreased gradually as 32.38[Formula: see text][Formula: see text], 29.37[Formula: see text][Formula: see text] and 23.19[Formula: see text][Formula: see text] for the arrays of SiNWs synthesized from Si substrate by Au coating of 8[Formula: see text]s, 15[Formula: see text]s and 25[Formula: see text]s respectively. Moreover, from Fowler–Nordheim plot, the turn-on field is observed to decrease from 16.56[Formula: see text][Formula: see text] for as-prepared to 8.77[Formula: see text][Formula: see text] for 25[Formula: see text]s Au sputtered SiNW arrays. The effective work functions of the electron emitting array of SiNWs have been improved from 0.5[Formula: see text]meV to 0.1[Formula: see text]meV.

We report an efficient and green approach for mass production of few layered graphene nanosheets (FLGNSs) by intercalation and exfoliation of pyrolytic graphite sheet in a simple protic, H 2 SO 4 electrolyte. The as-prepared FLGNSs at the optimum intercalate concentration of 0.5 M H 2 SO 4 is able to produce large domain of lateral dimension of 11–26 μm consisting of 4–6 stacked graphene layers, as confirmed by field emission scanning electron microscopy and atomic force microscopy, respectively. Surface oxygenation and a characteristic absorbance peak at 228 nm are well observed for electrochemical exfoliated FLGNSs from Fourier transform infrared spectroscopy and UV–Vis spectra respectively. (002) planes of the obtained graphene sheets have been confirmed from X-ray diffraction pattern. The characteristic Raman bands have been observed at 1354 cm-1 and 1590 cm-1 in the exfoliated FLGNSs.