Hybrid carbon nanomaterials, such as those that incorporate carbon nanotubes into graphene sheets, have been found to display interesting mechanical and electrical properties because of their covalent bonding and π-π stacking domains. However, synthesis of these hybrid materials is limited by the high energetic cost of techniques like chemical vapor deposition. Here, we demonstrate the solvent- and gas-free synthesis of a 2D carbon nanotube/graphene network through flash Joule heating of pristine carbon nanotubes. The relative proportion of each morphology in the hybrid material can be tuned by varying the pulse time, as confirmed by Raman spectroscopy and microscopy. Triboindentation of epoxy composites made with the hybrid material shows increases of 162% and 64% to the hardness and Young's modulus, respectively, compared with the neat epoxy. These results demonstrate that flash Joule heating can be used to inexpensively convert carbon nanotubes into a hybrid network of nanotubes and graphene for use as an effective reinforcing additive in epoxy composites.

Boron nitride nanotubes (BNNTs) have attracted attention for their predicted extraordinary properties; yet, challenges in synthesis and processing have stifled progress on macroscopic materials. Recent advances have led to the production of highly pure BNNTs. Here we report that neat BNNTs dissolve in chlorosulfonic acid (CSA) and form birefringent liquid crystal domains at concentrations above 170 ppmw. These tactoidal domains merge into millimeter-sized regions upon light sonication in capillaries. Cryogenic electron microscopy directly shows nematic alignment of BNNTs in solution. BNNT liquid crystals can be processed into aligned films and extruded into neat BNNT fibers. This study of nematic liquid crystals of BNNTs demonstrates their ability to form macroscopic materials to be used in high-performance applications.

Boron nitride nanotubes (BNNT) are poised to fill an electrically insulating, high-temperature, high strength niche. Despite significant progress over the past two decades, BNNTs are not yet synthesized in high enough quantity and quality to permit their use in engineering applications. The next necessary step to make BNNTs accessible for research and applications is to improve the availability of high-quality BNNTs. Here, we present a scalable bulk purification technique that yields high-purity BNNTs. Bulk synthesized material is introduced to a wet oxygen environment at elevated temperatures to remove elemental boron and hexagonal boron nitride impurities with a final yield of purified BNNTs near 10 wt %. This process shows full removal of impurities, as observed by scanning electron microscopy (SEM), cryogenic transmission electron microscopy (TEM), and high-resolution TEM. X-ray photoelectron spectroscopy (XPS) and infrared spectroscopy show minimal BNNT functionalization, while high-resolution TEM shows damage to large-diameter BNNTs.

The deployment of traditional radioactive isotopes as tracers has the drawback of environmental concerns. In this study, we investigated alternative luminescent zinc oxide quantum dots embedded silica (ZnO@SiO2) nanoparticles as tracers for oil reservoir applications. ZnO quantum dots (QDs) were prepared via solgel process having an average diameter of -5 nm. For the encapsulation of these ZnO QDs, tetraethyl orthosilicate (TEOS) was utilized to synthesize hydrophilic ZnO@SiO2 nanoparticles (H-NPs), while dimethyldiethoxysilane (DM DES) in combination with TEOS was used to prepare partially hydrophobic ZnO@SiO2 (PH-NPs). The fluorescence of bare ZnO QDs was compared to that of silica-coated Zn005iO(2) NPs in various solvents. The effects of cetyltrimethylammonium bromide (CTAB) surfactant and silica coatings on the fluorescence of ZnO QDs were investigated by photoluminescence spectroscopy. The fluorescence and structural properties of ZnO@SiO2 nano-tracers were examined in highly saline water and at elevated temperature to mimic the oil reservoir environment. The significant improvement in fluorescence emission stability was achieved for PH-NPs in harsh conditions, which advocates their potential use as a tracer material for oil exploration. (C) 2018 Elsevier B.V. All rights reserved.

Petroleum sulfonate (PS) salt surfactants that are insoluble in high-salinity water were encapsulated into 10-60 nm oil swollen micelles dispersed by a cocamidopropyl hydroxysultaine zwitterionic cosurfactant to form a highly stable nanofluid at elevated salinity (similar to 56 000 mg/L) and temperature (similar to 100 degrees C). The resulting "Nano-Surfactant (NS)" fluid enables an economic, efficient, and environmentally friendly enhanced oil recovery (EOR) capable of targeted delivery of PS salt surfactants-one of the most abundant and inexpensive industrial surfactants, yet cannot be used in most EOR operations because of its insolubility in high-salinity water-to residual oil without the need of massive amounts of surfactants. The NS formulations presented here can be easily prepared in the field by a simple one-pot, one-step procedure at ambient temperatures and with a minimal energy input. This article reports the preparation method of the NS and results, demonstrating their long-term colloidal and chemical stability at 100 degrees C, reduction of crude oil-high-salinity water interfacial tension (IFT) by 3 orders of magnitude (from similar to 10 to 0.008 mN/m), and improved mobilization of the trapped crude oil from the carbonate rock. Results point out the potential of NS formulations in enhancing oil mobilization under a variety of reservoir conditions. The NS platform described here can be utilized to encapsulate and deliver a variety of other chemical treatments, not only in oil recovery applications but also in others such as remediation of nonaqueous phase liquid-contaminated groundwater aquifers, well-drilling operations, and wellbore stimulation.

Laser-assisted materials fabrication is an advanced technique that has propelled recent carbon synthesis approaches. Direct laser writing on polyimide or lignocellulose materials by a CO2 laser has successfully transformed the substrates into hierarchical graphene. However, formation of other carbon allotropes such as diamond and fullerene remains challenging. Here, we report the direct synthesis of fluorinated nanodiamonds or fluorinated graphene by treating polytetrafluoroethylene (Teflon, or PTFE) with a 9.3 μm pulsed CO2 laser under argon; no exogenous fluorine source is needed. The laser is part of a commercial laser cutting/scribing system that is found in most machine shops. Therefore, it is a readily accessible tool. This discovery could inspire future development for the laser-assisted synthesis of functionalized carbon allotropes.

In the Experimental Procedures section, the order of addition of reagents in the description of the improved method is incorrect. The correct procedure is as follows: for the improved method, KMnO4 (18.0 g, 6 wt equiv) was slowly added in 6 equal portions to a 9:1 mixture of concentrated H2SO4/H3PO4 (360:40 mL) and graphite flakes (3.0 g, 1 wt equiv), producing a slight exotherm that should not exceed 35−40 °C. The reaction was then heated to 50 °C and stirred for 12 h. The reaction was cooled to room temperature and poured onto ice (400 mL) containing 30% H2O2 (3 mL). This correction is important because, in the instances where there would be different addition order, the KMnO4 might be in high concentration in the acid mixture, and this can become explosive.

This manuscript reports the industry's first proven reservoir nanoagents' design and describes a successful crosswell field trial using these inexpensive and environmentally friendly nanoparticles that offer an important advantage of fast and cheap fluorometric detection. Our fundamental nanoparticle tracer template, A-Dots, is intentionally geared towards the harsh but prolific carbonate reservoir environment of 100 degrees C temperature, 150,000 ppm salinity, and an abundant presence of divalent ions in the connate water. The A-Dots were manufactured on a scale of one metric ton from affordable and easily available commodity chemicals. They were injected into a watered-out part of the field and monitored at four nearby producer wells for two years. Monitoring of four neighboring producer wells over a period of 26 months confirmed nanoparticles' breakthrough at a single producer nearly 500 m from the injector at the reservoir level, thus, proving the nanoparticles' mobility and transport capability. The maximum concentration of the nanoagent in produced water was observed about 10 months after the injection matching the behavior of conventional small-molecule tracers used in the same pai4 of wells previously. This test supported our previous observations of satisfactory recovery of A-Dots in a single-well test by confirming their reservoir stability on industry relevant time scales and demonstrating the feasibility of their industrial production. The importance of this accomplishment is not in how sophisticated the sensing functionality of the tracer design is but rather in the nanoparticle stability, mobility, scalability, and field application potentials. Our findings render the concept of having active, reactive, and even communicative, in-situ reservoir nanoagents for underground sensing and intervention a well anticipated near-future reality.

Abstract Chemical and radioactive tracers have been used for decades in the oil industry to track injected fluids to map inter-well permeable paths (as passive tracers) and as active tracers to identify reservoirs that are specifically suited for EOR operations by detecting residual oil saturation. The down side of using these types of tracers is the high cost of materials, time consuming collection, costly lab analysis and high safety hazards of the materials themselves. Saudi Aramco's Reservoir Engineering Team has made significant progress towards using nanoparticles as active and passive reservoir tracers that are inexpensive, easy to produce and pose very low safety hazards personally or environmentally. Additionally, Aramco has been developing a portable stand-alone system that can detect these advanced nanoparticle tracers in real-time, directly from the well head with no need for sample collection or lab analysis and can run without operator intervention for at least three months. This paper presents the prototype stand-alone sensing system for advanced nanoparticle tracers which has the potential to transform the efficiency of current nanoparticle oil tracing practices by nearly 99% by reducing collection and processing time from around 10 hours to <5 minutes in real time. Recent results show the system's ability to separate, purify and detect fluorescent nanotracers from produced water to 0.1ppm levels in a portable inline process.

Abstract This manuscript reports the industry's first proven reservoir nanoagents' design and describes a successful multi-well field trial using these inexpensive and environmentally friendly nanoparticles that offer an important advantage of fast and cheap fluorometric detection. Our fundamental nanoparticle tracer template, A-Dots or Arab-D dots, is intentionally geared towards the harsh but prolific Arab-D carbonate reservoir environment of 100°C temperature, 150,000 ppm salinity, and an abundant presence of divalent ions in the connate water. The A-Dots were manufactured on a scale of one metric ton from affordable and easily available commodity chemicals. They were injected into a watered-out part of the field and monitored at four nearby producer wells for two years. Monitoring of four neighbouring producer wells over a period of 26 months confirmed nanoparticles' breakthrough at a single producer nearly 500 m from the injector at the reservoir level, thus, proving the nanoparticles' mobility and transport capability. The maximum concentration of the nanoagent in produced water was observed about 10 months after the injection matching the behavior of conventional small-molecule tracers used in the same pair of wells previously. The rate of A-Dots production correlated with the rate of water injection at the original injector well and followed it closely with a 10-month delay. This test bolstered our previous observations of satisfactory recovery of A-Dots in a single-well test by confirming their reservoir stability on industry relevant time scales and demonstrating the feasibility of their industrial production. The importance of this accomplishment is not in how sophisticated the sensing functionality of the tracer design is but rather in the nanoparticle stability, mobility, scalability, and field application potentials. Our findings render the concept of having active, reactive, and even communicative, in-situ reservoir nanoagents for underground sensing and intervention a well anticipated near-future reality.

This short manuscript highlights the industry's first proven reservoir nanoagents' design and demonstrates a successful multi-well field trial using these agents. Our fundamental nanoparticles tracer template, A-Dots or Arab-D Dots, is intentionally geared towards the harsh but prolific Arab-D carbonate reservoir environment of 100+°C temperature, 150,000+ppm salinity, and an abundant presence of divalent ions in the connate water. Preliminary analyses confirmed nanoparticles' breakthrough at a producer nearly 500m from the injector at the reservoir level; thus, proving the tracer nanoparticles' mobility and transport capability. This is considered industry-first and a breakthrough achievement complementing earlier accomplishments in regard to the nanoagents' reservoir stability with the first successful single well test and ease of scale up with the synthesis of one metric ton of this material. The importance of this accomplishment is not in how sophisticated is the sensing functionalities of this design but rather in its stability, mobility, scalability, and field application potentials. This renders the concept of having active, reactive, and even communicative, in-situ reservoir nanoagents for underground sensing and intervention a well anticipated near-future reality.

Electronic spin transport properties of graphene nanoribbons (GNRs) are influenced by the presence of adatoms, adsorbates and edge functionalization. To improve the understanding of the factors that influence the spin properties of GNRs, local (element) spin-sensitive techniques such as electron spin resonance (ESR) spectroscopy are important for spintronics applications. Here, we present results of multi-frequency continuous wave (CW), pulse and hyperfine sublevel correlation (HYSCORE) ESR spectroscopy measurements performed on oxidatively unzipped graphene nanoribbons (GNRs), which were subsequently chemically converted (CCGNRs) with hydrazine. ESR spectra at 336 GHz reveal an isotropic ESR signal from the CCGNRs, of which the temperature dependence of its line width indicates the presence of localized unpaired electronic states. Upon functionalization of CCGNRs with 4-nitrobenzene diazonium tetrafluoroborate, the ESR signal is found to be 2 times narrower than that of pristine ribbons. NH3 adsorption/desorption on CCGNRs is shown to narrow the signal, while retaining the signal intensity and g value. The electron spin-spin relaxation process at 10 K is found to be characterized by slow (163 ns) and fast (39 ns) components. HYSCORE ESR data demonstrate the explicit presence of protons and 13C atoms. With the provided identification of intrinsic point magnetic defects such as proton and 13C has been reported, which are roadblocks to spin travel in graphene-based materials, this work could help in advancing the present fundamental understanding on the edge-spin (or magnetic)-based transport properties of CCGNRs.

Abstract The ability to map injected fluids in hydrocarbon reservoirs with high resolution is a key goal for reservoir engineering and optimization. Saudi Aramco is developing tools and methodologies to map floodfront, locate bypassed oil, monitor the oil-water contact and detect super-k zones and fracture corridors prior to early water breakthrough at producing wells. Magnetic NanoMappers (MNM) is a new approach exploiting the use of Magnetic Nano-Particles (MNP) as contrast agents for mapping the floodfront inside the hydrocarbon reservoir. This approach takes advantage of the fact that electromagnetic (EM) waves speed slow down when they pass through magnetic media. Localizing MNP within injected fluids could provide a detailed map of fluids movements. Lab tests have recently demonstrated that the capability of MNM to locate MNP volumes hidden within a 2,000 liter tank (reservoir model) with high resolution. This paper will outline the MNM concept, laboratory testbed, results and future plans.

Graphene oxide nanoribbons (GONRs) and chemically reduced graphene nanoribbons (crGNRs) were dispersed at high concentrations in chlorosulfonic acid to form anisotropic liquid crystal phases. The liquid crystal solutions were spun directly into hundreds of meters of continuous macroscopic fibers. The relationship of fiber morphology to coagulation bath conditions was studied. The effects of colloid concentration, annealing temperature, spinning air gap, and pretension during annealing on the fibers' performance were also investigated. Heat treatment of the as-spun GONR fibers at 1500 °C produced thermally reduced graphene nanoribbon (trGNR) fibers with a tensile strength of 378 MPa, Young's modulus of 36.2 GPa, and electrical conductivity of 285 S/cm, which is considerably higher than that in other reported graphene-derived fibers. This better trGNR fiber performance was due to the air gap spinning and annealing with pretension that produced higher molecular alignment within the fibers, as determined by X-ray diffraction and scanning electron microscopy. The specific modulus of trGNR fibers is higher than that of the commercial general purpose carbon fibers and commonly used metals such as Al, Cu, and steel. The properties of trGNR fibers can be further improved by optimizing the spinning conditions with higher draw ratio, annealing conditions with higher pretensions, and using longer flake GONRs. This technique is a new high-carbon-yield approach to make the next generation carbon fibers based on solution-based liquid crystal phase spinning.

Here we show the efficacy of graphene oxide (GO) for rapid removal of some of the most toxic and radioactive long-lived human-made radionuclides from contaminated water, even from acidic solutions (pH < 2). The interaction of GO with actinides including Am(III), Th(IV), Pu(IV), Np(V), U(VI) and typical fission products Sr(II), Eu(III) and Tc(VII) were studied, along with their sorption kinetics. Cation/GO coagulation occurs with the formation of nanoparticle aggregates of GO sheets, facilitating their removal. GO is far more effective in removal of transuranium elements from simulated nuclear waste solutions than other routinely used sorbents such as bentonite clays and activated carbon. These results point toward a simple methodology to mollify the severity of nuclear waste contamination, thereby leading to effective measures for environmental remediation.