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Unconventional deposits such as extra heavy oil and bitumen represent a steadily increasing proportion of extracted fuels. The rheological properties of viscous crude oil represents a formidable impediment to their extraction, transportation, and processing and have necessitated considerable retooling and changes to process design. In this work, we demonstrate that highly textured inorganic substrates generated by depositing ZnO nanotetrapods onto periodically ordered stainless steel mesh substrates exhibit viscous oil contact angles exceeding 150° as well as enable the facile gliding of viscous oil. Such functionality is derived as a result of multiscale texturation and porosity achieved within these substrates, which are characterized by trapping of plastronic air pockets at the solid/liquid interface. Further reduction of the surface energy has been achieved by constituting a helical highly ordered self-assembled monolayer of a perfluorinated phosphonic acid on the ZnO surfaces. Such structures are str...

Endemic fluorosis disease has become a major geo-environmental health care issue caused by fluoride ion. High-efficiency and low-cost materials to uptake fluoride from water have been a chal-lenge for scientists and engineers. Here, we report a low-cost process by utilising low-cost starting materials to develop nanocomposite adsorbents for fluoride uptake from water. Bermuda grass as a starting source material converted into nanocomposite carbon fibers upon heat treatment at 800°C for one hour in Nitrogen atmosphere in the presence of metal oxides. Iron oxide-based nanocomposite (IBNC) is performing high (≈97%) removal of fluoride ion at a contact time of 60 minutes (pH 4) followed by titania-based nanocomposite (TBNC) (≈92%) and micro carbon fiber (≈88%) respectively. The phenomenon of fluoride ion uptake is realised by Freundlich adsorption model, and both adsorption capacity and adsorption intensity for IBNC are higher than those for TBNC and micro carbon fiber.

The classical orthorhombic layered phase of V2O5 has long been regarded as the thermodynamic sink for binary vanadium oxides and has found great practical utility as a result of its open framework and easily accessible redox states. Herein, we exploit a cation-exchange mechanism to synthesize a new stable tunnel-structured polymorph of V2O5 (ζ-V2O5) and demonstrate the subsequent ability of this framework to accommodate Li and Mg ions. The facile extraction and insertion of cations and stabilization of the novel tunnel framework is facilitated by the nanometer-sized dimensions of the materials, which leads to accommodation of strain without amorphization. The topotactic approach demonstrated here indicates not just novel intercalation chemistry accessible at nanoscale dimensions but also suggests a facile synthetic route to ternary vanadium oxide bronzes (MxV2O5) exhibiting intriguing physical properties that range from electronic phase transitions to charge ordering and superconductivity.

A novel synthetic approach is developed wherein graphene oxide and oxidized multiwalled carbon nanotubes are used as curing agents to induce cross-linking of an epoxy resin, thereby yielding a nanostructured epoxy composite with excellent dispersion of the carbon nanomaterials. This method allows for incorporation of up to 50 wt% of carbon nanomaterials within the polymeric matrix. The combination of covalent bonding and π–π interactions ensure excellent dispersibility of the nanomaterials within the polymeric matrix. These nanocomposites offer an alternative to the hazardous high-temperature fluorination and amine curing reactions that are usually required to formulate epoxy composite systems. Structural, mechanical, and morphological characterization of the composite material confirms the distribution, integrity, and potential to resist corrosion on a steel surface while also indicating the excellent adhesion and flexibility of the nanocomposite coatings.

Corrosion of base metals represents a tremendous problem that has spurred a global search for cost-effective and environmentally friendly alternatives to current corrosion-inhibiting technologies. In this work, we report a novel sustainable hybrid Mg/poly(ether imide) (PEI) nanocomposite coating that provides corrosion protection to low-alloy steels at relatively low coating thicknesses and with reduced weight as compared to conventional metallic coatings. The coatings are constituted using Mg nanoplatelets dispersed within a polyamic acid matrix that is subsequently imidized on the steel substrate to form PEI. The coatings function through a combination of sacrificial cathodic protection (afforded by the preferential oxidation of the Mg nanoplatelets), anodic passivation through precipitation of corrosion products, and the inhibitive action of the PEI polymeric matrix. The use of nanostructured Mg allows for reduced coating thicknesses and a smoother surface finish, whereas the PEI matrix provides excell...

Single-walled carbon nanotubes (SWNTs) reinforced with uniform distribution of magnesium nanoparticles were synthesized by a solution reduction method using a Grignard reagent and lithium naphthalide. Magnesium nanoparticles were observed to be of an average size of 4.5±0.5 nm. Raman data indicated distinct diameter selectivity for larger-diameter metallic SWNTs of 2.21 nm and some degree of de-bundling of the nanotube bundles upon the incorporation of the magnesium nanoparticles.

Annealing graphene oxide under an ammonia environment provides a facile approach to defunctionalise this material while simultaneously enabling nitrogen incorporation en route to the preparation of chemically derived graphene. Here, we use X-ray photoemission spectroscopy (XPS) in conjunction with near-edge X-ray absorption fine-structure (NEXAFS) spectroscopy to probe both the global recovery of electronic structure in this material as well as to monitor evolution of the local structure of incorporated nitrogen atoms when graphene oxide is reduced under an ammonia gas environment at ambient and low pressures in the temperature range between 250 and 1000 °C. The local structure and extent of recovery of the π-conjugated framework is correlated to electrical conductivity measurements. Angle-resolved C K-edge NEXAFS spectra along with O K-edge NEXAFS and C 1s high-resolution XPS spectra suggest that hydroxyl and epoxide functional groups on the basal plane of graphene oxide are eliminated upon annealing to a temperature of 250 °C, bringing about substantial restoration of the π-conjugated framework of graphene. Furthermore, an increase in the in-plane orientation of constituent graphene oxide flakes is observed up to a temperature of 750 °C for annealing under both sets of conditions and is manifested as a greater spread in the intensity of the C K-edge π* resonance as a function of angle of incidence of the X-ray beam. Angle-resolved N K-edge NEXAFS spectra and high-resolution N 1s XPS spectra supplement the global view of recovery of π-conjugation with a local perspective of the chemical bonding environments of incorporated nitrogen atoms. Three distinct modes of nitrogen incorporation are evidenced: amine or nitrile like (N1), pyridinic (N2), and substitutional/graphitic (N3). The data suggest that nitrogen is initially incorporated as nitrile like functionalities at lower temperatures with these moieties protruding above and below the graphene basal plane; however, the nitrile and amine groups are subsequently transformed at higher temperatures through the elimination of oxygenated functional groups and reconstitution of the sp2-hybridized network to in-plane pyridinic and graphitic moieties. The latter two configurations are seen to substantially enhance the conductivity of reduced graphene oxide.

A comparative evaluation of the efficacy of different reducing agents in defunctionalizing graphene oxide is performed using near-edge X-ray absorption fine structure (NEXAFS) spectroscopy at carbon and oxygen K-edges. The relative intensities of π* and σ* resonances in carbon K-edge NEXAFS spectra suggest relatively high extents of recoveries of π-conjugation upon reduction using vapor-phase phenylhydrazine or hydrazine as well as neat phenylhydrazine. The use of these reducing agents in combination with modest thermal annealing appears to be particularly effective for de-epoxidation and decarboxylation of graphene oxide. Polarized carbon K-edge NEXAFS spectroscopy measurements allow evaluation of the extent of warping or planarity induced upon chemical reduction. Treatment with vapor phenylhydrazine and subsequent thermal annealing entirely disrupts the alignment of reduced graphene oxide while facilitating substantial recovery of π conjugation. In contrast, annealing subsequent to treatment with vapor-...

The growth of carbon nanotubes (CNTs) on sheet metal surfaces (including low- and high-alloyed steel and Ni-plated steel) has been explored using a mixture of CO, CO 2 , and H 2 as the precursor feedstock in a thermal chemical vapor deposition process. The influence of various experimental parameters such as the reactor temperature, reaction time, and precursor composition on the yield, purity, and dimensions of the CNTs has been elucidated. Addition of CO 2 during CNT growth leads to higher carbon deposition rates, especially for low- and high-alloyed steel. The diameters of the obtained CNTs range from 12 to 300 nm at carbon deposition rates of ∼0.3 mg cm −2 min −1 . The CNTs are observed to be uniformly distributed and adhered firmly to the substrates. The experimental conditions for CNT growth on sheet metal surfaces are very similar to concentrations and temperatures of a typical effluent stream of the steel industry. This process thus holds potential to harness waste gases to fabricate CNT-based coatings that impart added functionality to sheet metals, while further reducing the carbon footprint of steel plants.

The oxidative chemistry of graphite has been investigated for over 150 years and has attracted renewed interest given the importance of exfoliated graphene oxide as a precursor to chemically derived graphene. However, the bond connectivities, steric orientations, and spatial distribution of functional groups remain to be unequivocally determined for this highly inhomogeneous nonstoichiometric material. Here, we demonstrate the application of principal component analysis to scanning transmission X-ray microscopy data for the construction of detailed real space chemical maps of graphene oxide. These chemical maps indicate very distinct functionalization motifs at the edges and interiors and, in conjunction with angle-resolved near-edge X-ray absorption fine structure spectroscopy, enable determination of the spatial location and orientations of functional groups. Chemical imaging of graphene oxide provides experimental validation of the modified Lerf-Klinowski structural model. Specifically, we note increased contributions from carboxylic acid moieties at edge sites with epoxide and hydroxyl species dominant within the interior domains.

Interfacing graphene with metal oxides is of considerable technological importance for modulating carrier density through electrostatic gating as well as for the design of earth-abundant electrocatalysts. Herein, we probe the early stages of the atomic layer deposition (ALD) of HfO2 on graphene oxide using a combination of C and O K-edge near-edge X-ray absorption fine structure spectroscopies and X-ray photoelectron spectroscopy. Dosing with water is observed to promote defunctionalization of graphene oxide as a result of the reaction between water and hydroxyl/epoxide species, which yields carbonyl groups that further react with migratory epoxide species to release CO2. The carboxylates formed by the reaction of carbonyl and epoxide species facilitate binding of Hf precursors to graphene oxide surfaces. The ALD process is accompanied by recovery of the π-conjugated framework of graphene. The delineation of binding modes provides a means to rationally assemble 2D heterostructures.

Anisotropic Mg nanowires have been successfully prepared by electrocrystallization of Grignard's reagents thought to proceed via a modified faces, steps, and kinks (FSK) mechanism. Mg nanoparticles with roughly hexagonal shapes have also been obtained via chemical reduction of the same Grignard's reagents.

In this topical review article, we attempt to capture recent advances in the development of sustainable hybrid nanocomposite coatings for the corrosion inhibition of structural metals. Spurred primarily by the urgent imperative of replacing hexavalent chromium but also driven by concerns regarding the environmental impact of organic solvents, materials criticality considerations, the need to maintain structural integrity and function under extreme environments, and a renewed impetus towards lightweighting, the design of new coating concepts has seen an explosion of activity. We discuss varying modes of corrosion inhibition and the drive towards multicomponent nanostructured coatings that synergistically unite multiple modes of corrosion inhibition within a single coating system. Nanocomposite coatings in which nanoparticles of one phase are dispersed within a continuous phase, usually a polymeric matrix, provide a modular design approach to multifunctional coatings provided fundamental challenges such as dispersion and compatibility can be resolved. By dint of their high surface-to-volume ratios, the incorporation of nanoparticles profoundly modifies the adjacent polymeric matrix, giving rise to an 'interphase' region with modified properties, at relatively low filler loadings. The implications of incorporating metallic, porous metal oxide, and carbon nanomaterials (graphene and carbon nanotubes) within polymeric matrices are explored with an emphasis on active corrosion inhibition. The availability of high-quality nanoparticles that are either electroactive (e.g., metals, graphene, carbon nanotubes, etc.) or are capable of serving as reservoirs for active corrosion inhibitors (e.g., porous silicon oxide, layered double hydroxides, halloysite) provides unprecedented functionality and opportunities for multifunctional coatings. The review emphasizes mechanistic considerations where these have been elucidated with a view towards developing systematic design principles for corrosion inhibition. The outlook for the future design of multimodal coatings is presented with an emphasis on the emergence of rational design of nanoparticles, advances in nanoparticle surface chemistry, high-throughput testing, materials informatics, multiscale modeling, and integrated computational materials engineering approaches.

The unusual electronic structure of graphene characterized by linear energy dispersion of bands adjacent to the Fermi level underpins its remarkable transport properties. However, for practical device integration, graphene will need to be interfaced with other materials: 2D layered structures, metals (as ad-atoms, nanoparticles, extended surfaces, and patterned metamaterial geometries), dielectrics, organics, or hybrid structures that in turn are constituted from various inorganic or organic components. The structural complexity at these nanoscale interfaces holds much promise for manifestation of novel emergent phenomena and provides a means to modulate the electronic structure of graphene. In this feature article, we review the modifications to the electronic structure of graphene induced upon interfacing with disparate types of materials with an emphasis on iterative learnings from theoretical calculations and electronic spectroscopy (X-ray absorption fine structure (XAFS) spectroscopy, scanning transmission X-ray microscopy (STXM), angle-resolved photoemission spectroscopy (ARPES), and X-ray magnetic circular dichroism (XMCD)). We discuss approaches for engineering and modulating a bandgap in graphene through interfacial hybridization, outline experimental methods for examining electronic structure at interfaces, and overview device implications of engineered interfaces. A unified view of how geometric and electronic structure are correlated at interfaces will provide a rational means for designing heterostructures exhibiting emergent physical phenomena with implications for plasmonics, photonics, spintronics, and engineered polymer and metal matrix composites.

The chemical reduction of exfoliated graphene oxide (GO) has gained widespread acceptance as a scalable route for the preparation of chemically derived graphene albeit with remnant topological defects and residual functional groups that preclude realization of the conductance of single-layered graphene. Reduction of GO with hydrazine is substantially effective in restoring the π-conjugated framework of graphene and leads to about a five-to-six orders of magnitude decrease of sheet resistance, but has also been found to result in incidental nitrogen incorporation. Here, the authors use a combination of x-ray photoelectron spectroscopy (XPS) and C, O, and N K-edge near-edge x-ray absorption fine structure (NEXAFS) spectroscopy to examine the local geometric and electronic structure of the incorporated nitrogen species. Both NEXAFS and XPS data suggest substantial recovery of the sp2-hybridized graphene framework upon chemical reduction and removal of epoxide, ketone, hydroxyl, and carboxylic acid species. Two distinct types of nitrogen atoms with pyridinic and pyrrolic character are identified in reduced graphene oxide. The N K-edge NEXAFS spectra suggest that the nitrogen atoms are stabilized within aromatic heterocycles such as pyrazole rings, which has been further corroborated by comparison to standards. The pyrazole fragments are thought to be stabilized by reaction of diketo groups on the edges of graphene sheets with hydrazine. The incorporation of nitrogen within reduced graphene oxide thus leads to local bonding configurations very distinct from substitutional doping observed for graphene grown by chemical vapor deposition in the presence of NH3.

In situ near-edge x-ray absorption fine structure (NEXAFS) spectroscopy is used in conjunction with measurements of sheet resistance to examine the electronic structure recovery of graphene oxide upon thermal annealing. Several different defunctionalization regimes are identified with the initial removal of basal plane epoxide and hydroxyl functionalities and subsequent elimination of carboxylic acid moieties. The measured electrical conductivity is closely correlated to recovery of the conjugated π structure. A pronounced broadening of the C K-edge π* resonance is observed upon annealing and is ascribed to the superposition of the NEXAFS signatures of sp2-hybridized domains of varying dimensionality. Such incipient conjugated domains generated upon thermal defunctionalization mediate variable range hopping transport and further lead to an increase in the electrical conductance. Finally, both C K-edge and O K-edge spectra suggest that ring ether functionalities such as pyrans or furans and/or 1,2- and 1,4...