Deposits of clastic carbonate-dominated (calciclastic) sedimentary slope systems in the rock record have been identified mostly as linearly-consistent carbonate apron deposits, even though most ancient clastic carbonate slope deposits fit the submarine fan systems better. Calciclastic submarine fans are consequently rarely described and are poorly understood. Subsequently, very little is known especially in mud-dominated calciclastic submarine fan systems. Presented in this study are a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) that reveals a >250 m thick calciturbidite complex deposited in a calciclastic submarine fan setting. Seven facies are recognised from core and thin section characterisation and are grouped into three carbonate turbidite sequences. They include: 1) Calciturbidites, comprising mostly of highto low-density, wavy-laminated bioclast-rich facies; 2) low-density densite mudstones which are characterised by planar laminated and unlaminated muddominated facies; and 3) Calcidebrites which are muddy or hyper-concentrated debrisflow deposits occurring as poorly-sorted, chaotic, mud-supported floatstones. These

Phd by thesis

The surface science of titanium dioxide

In this work we present a low cost and scalable technique, via ambient pressure chemical vapor deposition (CVD) on polycrystalline Ni films, to fabricate large area (∼cm2) films of single- to few-layer graphene and to transfer the films to nonspecific substrates. These films consist of regions of 1 to ∼12 graphene layers. Single- or bilayer regions can be up to 20 μm in lateral size. The films are continuous over the entire area and can be patterned lithographically or by prepatterning the underlying Ni film. The transparency, conductivity, and ambipolar transfer characteristics of the films suggest their potential as another materials candidate for electronics and opto-electronic applications.

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Large Area, Few-Layer Graphene Films on Arbitrary Substrates by Chemical Vapor Deposition

Raman spectroscopy in graphene

Nanocrystals are fundamental to modern science and technology. Mastery over the shape of a nanocrystal enables control of its properties and enhancement of its usefulness for a given application. Our aim is to present a comprehensive review of current research activities that center on the shape-controlled synthesis of metal nanocrystals. We begin with a brief introduction to nucleation and growth within the context of metal nanocrystal synthesis, followed by a discussion of the possible shapes that a metal nanocrystal might take under different conditions. We then focus on a variety of experimental parameters that have been explored to manipulate the nucleation and growth of metal nanocrystals in solution-phase syntheses in an effort to generate specific shapes. We then elaborate on these approaches by selecting examples in which there is already reasonable understanding for the observed shape control or at least the protocols have proven to be reproducible and controllable. Finally, we highlight a number of applications that have been enabled and/or enhanced by the shape-controlled synthesis of metal nanocrystals. We conclude this article with personal perspectives on the directions toward which future research in this field might take.

Shape‐Controlled Synthesis of Metal Nanocrystals: Simple Chemistry Meets Complex Physics?

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Surface chemistry of catalysis by gold

Using spin-density functional theory we investigated various possible structures of the hematite (0001) surface. Depending on the ambient oxygen partial pressure, two geometries are found to be particularly stable under thermal equilibrium: one being terminated by iron and the other by oxygen. Both exhibit huge surface relaxations ( $\ensuremath{-}57%$ for the Fe and $\ensuremath{-}79%$ for the O termination) with important consequences for the surface electronic and magnetic properties. With scanning tunneling microscopy we observe two different surface terminations coexisting on single crystalline $\ensuremath{\alpha}$- ${\mathrm{Fe}}_{2}{\mathrm{O}}_{3}$ (0001) films, which were prepared in high oxygen pressures.

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The Hematite ( α- Fe 2 O 3 ) (0001) Surface: Evidence for Domains of Distinct Chemistry

Metallic nanoparticles finely dispersed over oxide supports have found use as heterogeneous catalysts in many industries including chemical manufacturing, energy-related applications and environmental remediation. The compositional and structural complexity of such nanosized systems offers many degrees of freedom for tuning their catalytic properties. However, fully rational design of heterogeneous catalysts based on an atomic-level understanding of surface processes remains an unattained goal in catalysis research.Researchers have used surface science methods and metal single crystals to explore elementary processes in heterogeneous catalysis. In this Account, we use more realistic materials that capture part of the complexity inherent to industrial catalysts. We assess the impacts on the overall catalytic performance of characteristics such as finite particle size, particle structure, particle chemical composition, flexibility of atoms in clusters, and metal–support interactions.To prepare these materia...

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Nanoparticles for heterogeneous catalysis: new mechanistic insights.

Size effects in adsorption and reactivity of supported metal particles have been observed for at least two decades. In recent years, gold nanoparticles have received attention for their extraordinary catalytic activity for reactions such as low temperature CO oxidation. A number of different theories have been advanced to explain this reactivity in terms of special reaction sites created by the metal–support interface. Goodman's group invoked quantum effects to explain a maximum in CO oxidation activity and suggested that particle thickness, in this case two atomic layers, may be the key parameter. Herein, through a combination of scanning tunneling microscopy (STM), temperature programmed desorption (TPD), and infrared reflection absorption spectroscopy (IRAS), we report the first experimental evidence that thin islands of gold in fact have the same CO adsorption behavior as large gold particles and extended gold surfaces. Therefore observed differences in reactivity of gold nanoparticles are proposed to arise from the presence of highly uncoordinated gold atoms. We have previously found that palladium exhibits twodimensional (2D) growth on a FeO(111) thin film, forming large monolayer islands, which display CO adsorption behavior that is different from bulk palladium. However, we have found in the case of gold that the transition from 2Dto 3D-growth occurs at a very low coverage ( 0.1 monolayers). Therefore, in the present work, we re-examine the situation at these low coverages to determine whether 2D gold structures also show deviations in CO adsorption behavior from the bulk. For coverage up to 0.1 : (effective thickness), gold forms islands of monolayer height (Figure 1a). The inset in Figure 1a shows that these monolayer islands are well shaped. At further increasing coverage the nucleation density remains fairly constant and two-layer particles form. Finally, at highest coverage studied ( 2 :), Au deposits of up to 7 nm in diameter and 4–5 layers in height are seen (Figure 1b). Note that unlike many other cases of nucleation and growth on oxide films the metal particles nucleate on regular sites of the FeO films. This implies that one may study the role of layer thickness independently of the influence of defects.

Do Quantum Size Effects Control CO Adsorption on Gold Nanoparticles

Under low-pressure conditions, hydrogenation of alkenes, such as 2-pentene and ethene, is shown to occur on supported palladium nanoparticles, whereas single-crystal palladium surfaces are inactive. This finding is rationalized on the basis of the accessibility of weakly bound subsurface hydrogen (see picture), which is enhanced on particles of nanometer dimensions.

Shamil K. Shaikhutdinov

Papers

Surface chemistry of catalysis by gold

The Hematite ( α- Fe 2 O 3 ) (0001) Surface: Evidence for Domains of Distinct Chemistry

Nanoparticles for heterogeneous catalysis: new mechanistic insights.

Do Quantum Size Effects Control CO Adsorption on Gold Nanoparticles

Hydrogenation on metal surfaces: why are nanoparticles more active than single crystals?