Russell R. Chianelli

Asphaltenes are the molecular components of Asphalts and have polyaromatic hydrocarbon (PAH) structures similar to nanographenes. Thus, organic-based dye sensitized solar cells can be produced from asphaltenes. In addition, graphene based structures doped with transition metals can be synthesized from asphaltenes. These materials are simple to synthesize and inexpensive relative to other methods for doping graphene. Thus, what is considered a “Waste Material - Tar” can now be utilized in several important applications. These novel materials from asphaltene are also termed Discotic Liquid Crystals (DLC) and now have great potential in many areas, because of novel and valuable properties, easy synthesis and low cost.

We present the chemical synthesis of hexaniobate nanotubes using two routes, (1) starting material K₄Nb₆O₁₇ and (2) parent material of H₄Nb₆O₁₇ via ion exchange. The as-synthesized materials were exfoliated by adjusting the pH to 9–10 using tetra-n-butylammonioum hydroxide (TBA⁺OH⁻), leading to a formation of hexaniobate nanotubes. In order to understand morphology a full characterization was conducted using SEM, HRTEM, BET and powder-XRD. The photocatalytic activity was evaluated using photolysis method using Bromocresol Green (BG) and Methyl Orange (MO) as model contaminants. Results indicate a nanotube porous oxide with large porous and surface area; the photocatalytic activity is about 95% efficient when comparing with commercial TiO₂.

The chemical synthesis of gold nanoparticles (NP) by using gold (III) chloride trihydrate (HAuCl∙3H₂O) and sodium citrate as a reducing agent in aqueous conditions at 100 °C is presented here. Gold nanoparticles areformed by a galvanic replacement mechanism as described by Lee and Messiel. Morphology of gold-NP was analyzed by way of high-resolution transmission electron microscopy; results indicate a six-fold icosahedral symmetry with an average size distribution of 22 nm. In order to understand the mechanical behaviors, like hardness and elastic moduli, gold-NP were subjected to nanoindentation measurements—obtaining a hardness value of 1.72 GPa and elastic modulus of 100 GPa in a 3–5 nm of displacement at the nanoparticle’s surface.

The interaction of thioindigo and the phyllosilicate clay sepiolite is investigated using density functional theory (DFT) and molecular orbital theory (MO). The best fit to experimental UV/Vis spectra occurs when a single thioindigo molecule attaches via Van der Waals forces to a tetrahedrally coordinated cation with an additional nearby tetrahedrally coordinated also present. The thioindigo molecule distorts from its planar structure, a behavior consistent with a color change. Due to the weak interaction between thioindigo and sepiolite we conclude that the thioindigo molecule must be trapped in a channel, an observation consistent with previous experimental studies. Future computational studies will look at the interaction of indigo with sepiolite.

Salt cedars (Tamarix) are invasive halophytic species and heavy water consumers. However, Tamarix possesses interesting characteristics accounting for its opportunistic and resilient abilities: analogous to a miniature photodesalinization machine, it thrives on saline soils toxic to most plants. Here we observe, document, and reveal the salt separation process of T. ramosissima. Specimens were cultivated under controlled artificial conditions, then analyzed by microscopic and spectroscopic techniques. Tamarix ramosissima is shown to produce varied morphologies of salt crystal aggregates from vesiculated trichomes and possess the ability to separate anions and cations. Sodium chloride, potassium chloride (KCl), and potassium sodium sulfate [K_2.25Na_1.75(SO₄)₂] were major exuded salt crystal phases, with smaller quantities of other phases present. Compositions of crystals exuded by individual plants were consistent with compositions of the soils they grew on. Although T. ramosissima may be an invasive nuisance, it may possess other worthwhile attributes such as the potential to be a viable phytoremediator and environmental indicator.

-Évolution des propriétés catalytiques en hydrodésulfurisation en fonction de la position du métal de transition dans la classification périodique : intuition et théorie-Le besoin d'hydrogéner du charbon afin d'obtenir des combustibles liquides devenant pressant dans les années 1920, des catalyseurs constitués de sulfure de métal de transition (TMS) ont été utilisés. Sabatier a reçu le prix Nobel en 1912 pour avoir décrit le phénomène d'hydrogénation par des métaux de transition. Cependant, lorsque les métaux de transition étaient utilisés pour hydrogéner du charbon, les TMS apparaissaient comme des états catalytiques stables en raison de leur teneur élevée en sulfure dans les liquides dérivés du charbon. À partir des années 1920-1930, I.G. Farbenindustrie A.G. a testé plus de 6000 catalyseurs. C'est à partir de là que le Co (Ni)/Mo/Al 2 O 3 moderne est apparu.

Single layer transition metal sulfides (SLTMS) such as MoS₂, WS₂, and ReS₂, play an important role in catalytic processes such as the hydrofining of petroleum streams, and are involved in at least two of the slurry‐catalyst hydroconversion processes that have been proposed for upgrading heavy petroleum feed and other sources of hydrocarbon fuels such as coal and shale oils. Additional promising catalytic applications of the SLTMS are on the horizon. The physical, chemical, and catalytic properties of these materials are reviewed in this report. Also discussed are areas for future research that promise to lead to advanced applications of the SLTMS.

Development of synchrotron techniques for the determination of the structure of disordered, amorphous and surface materials has exploded over the past 20 years owing to the increasing availability of high-flux synchrotron radiation and the continuing development of increasingly powerful synchrotron techniques. These techniques are available to materials scientists who are not necessarily synchrotron scientists through interaction with effective user communities that exist at synchrotrons such as the Stanford Synchrotron Radiation Laboratory. In this article the application of multiple synchrotron characterization techniques to two classes of materials defined as 'surface compounds' is reviewed. One class of surface compounds are materials like MoS(2-x)C(x) that are widely used petroleum catalysts, used to improve the environmental properties of transportation fuels. These compounds may be viewed as 'sulfide-supported carbides' in their catalytically active states. The second class of 'surface compounds' are the 'Maya blue' pigments that are based on technology created by the ancient Maya. These compounds are organic/inorganic 'surface complexes' consisting of the dye indigo and palygorskite, common clay. The identification of both surface compounds relies on the application of synchrotron techniques as described here.