Dario Stacchiola

Abstract: The transformation of CO2 into alcohols or other hydrocarbon compounds is challenging because of the difficulties associated with the chemical activation of CO2 by heterogeneous catalysts. Pure metals and bimetallic systems used for this task usually have low catalytic activity. Here we present experimental and theoretical evidence for a completely different type of site for CO2 activation: a copper-ceria interface that is highly efficient for the synthesis of methanol. The combination of metal and oxide sites in the copper-ceria interface affords complementary chemical properties that lead to special reaction pathways for the CO2→CH3OH conversion.

Abstract: The electronic properties of Pt nanoparticles deposited on CeO(2)(111) and CeO(x)/TiO(2)(110) model catalysts have been examined using valence photoemission experiments and density functional theory (DFT) calculations. The valence photoemission and DFT results point to a new type of "strong metal-support interaction" that produces large electronic perturbations for small Pt particles in contact with ceria and significantly enhances the ability of the admetal to dissociate the O-H bonds in water. When going from Pt(111) to Pt(8)/CeO(2)(111), the dissociation of water becomes a very exothermic process. The ceria-supported Pt(8) appears as a fluxional system that can change geometry and charge distribution to accommodate adsorbates better. In comparison with other water-gas shift (WGS) catalysts [Cu(111), Pt(111), Cu/CeO(2)(111), and Au/CeO(2)(111)], the Pt/CeO(2)(111) surface has the unique property that the admetal is able to dissociate water in an efficient way. Furthermore, for the codeposition of Pt and CeO(x) nanoparticles on TiO(2)(110), we have found a transfer of O from the ceria to Pt that opens new paths for the WGS process and makes the mixed-metal oxide an extremely active catalyst for the production of hydrogen.

Abstract: Graphene, a two-dimensional carbon sheet, has attracted great interest due to its unique properties. To explore its practical applications, large-scale synthesis with controllable integration of individual graphene sheets is essential. To date, numerous approaches have been developed for graphene synthesis, including mechanical cleavage, epitaxial growth, and chemical vapor deposition. All of those techniques are used to prepare flat graphene sheets on a substrate. Chemical exfoliation of graphite has been applied to prepare graphene oxide solutions and graphene-based composite materials. Recently, tuning graphene shapes is attracting much attention. Cheng and co-workers synthesized graphene foam using porous Ni foam as a template for the CVD growth of graphene, followed by etching away the Ni skeleton. The graphene foam consists of an interconnected flexible network of graphene as the fast transport channel of charge carriers for high electrical conductivity. Ruoff et al. prepared porous graphene paper from microwave exfoliated graphene oxide by KOH activation. The porous graphene, which has an ultra-high surface area and a high electrical conductivity, was exploited for supercapacitor cells, leading to high values of gravimetric capacitance and energy density. Feng, M llen, and co-workers synthesized hierarchical macroand mesoporous graphene frameworks (GFs). The GFs exhibited excellent performance for electrochemical capacitive energy storage. Yu et al. and Qu et al. fabricated graphene tubes that could be selectively functionalized for desirable applications. Choi et al. synthesized macroporous graphene using polystyrene colloidal particles as sacrificial templates in graphene oxide suspension, and the pore sizes can be tuned by controlling template particle size. These important results represent a significant topic—tuning the properties of graphene sheets by controlling their shapes. However, it is still a challenge to synthesize three-dimensional graphene (3D) with a desirable shape. Herein, we develop a novel strategy for the synthesis of a new type of graphene sheet with a 3D honeycomb-like structure by a simple reaction between Li2O and CO. Furthermore, these graphene sheets exhibited excellent catalytic performance as a counter electrode for dye-sensitized solar cells (DSSCs) with an energy conversion efficiency as high as 7.8%, which is comparable to that of an expensive platinum electrode. Li2O is widely exploited as a promoter in catalysts to inhibit carbon formation. However, this general principle is challenged by this work, in which Li2O is used to react with CO to form graphene-structured carbon [Eq. (1)]

Abstract: The high thermochemical stability of CO2 makes it very difficult to achieve the catalytic conversion of the molecule into alcohols or other hydrocarbon compounds, which can be used as fuels or the starting point for the generation of fine chemicals. Pure metals and bimetallic systems used for the CO2 → CH3OH conversion usually bind CO2 too weakly and, thus, show low catalytic activity. Here, we discuss a series of recent studies that illustrate the advantages of metal–oxide and metal–carbide interfaces when aiming at the conversion of CO2 into methanol. CeOx/Cu(111), Cu/CeOx/TiO2(110), and Au/CeOx/TiO2(110) exhibit an activity for the CO2 → CH3OH conversion that is 2–3 orders of magnitude higher than that of a benchmark Cu(111) catalyst. In the Cu–ceria and Au–ceria interfaces, the multifunctional combination of metal and oxide centers leads to complementary chemical properties that open active reaction pathways for methanol synthesis. Efficient catalysts are also generated after depositing Cu and Au on T...

Abstract: =0.03 nA. Theheight image at the bottom right, showing the inside of a ceria island,was taken at imaging conditions of 2.7 V, 0.05 nA. The scheme (bot-tom left) was composed using the line profile indicated by the greenline shown near the middle of the top right image.[*] Dr. J. A. Rodriguez, Dr. J. Graciani, Dr. J. B. Park, Dr. F. Yang,Dr. D. Stacchiola, Dr. S. D. Senanayake, Dr. S. Ma, Dr. P. Liu,Dr. J. HrbekChemistry Department, Brookhaven National LaboratoryUpton, NY 11973 (USA)Fax: ( +1)631-344-5815E-mail: rodrigez@bnl.govProf. J. Evans, Prof. M. PrezFacultad de Ciencias, Universidad Central de VenezuelaCaracas 1020A (Venezuela)Prof. J. F. SanzDepartamento de Qumica Fsica, Universidad de Sevilla41012-Seville (Spain)[**] TheworkperformedatBNLwassupportedbytheUSDepartmentofEnergy, Office of Basic Energy Sciences, under contract DE-AC02-98CH10886. J.E. and M.P. are grateful to INTEVEP for partialsupport of the work carried out at the UCV. The work done at Sevillewas funded by MICINN, grant no MAT2008-04918 and theBarcelona Supercomputing Center—Centro Nacional de Super-computacin (Spain).Supporting information for this article is available on the WWWunder http://dx.doi.org/10.1002/anie.200903918.

Abstract: 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

Abstract: Graphene and other 2D atomic crystals are of considerable interest in catalysis because of their unique structural and electronic properties. Over the past decade, the materials have been used in a variety of reactions, including the oxygen reduction reaction, water splitting and CO2 activation, and have been shown to exhibit a range of catalytic mechanisms. Here, we review recent advances in the use of graphene and other 2D materials in catalytic applications, focusing in particular on the catalytic activity of heterogeneous systems such as van der Waals heterostructures (stacks of several 2D crystals). We discuss the advantages of these materials for catalysis and the different routes available to tune their electronic states and active sites. We also explore the future opportunities of these catalytic materials and the challenges they face in terms of both fundamental understanding and the development of industrial applications.

Abstract: We introduce density functional theory and review recent progress in its application to transition metal chemistry. Topics covered include local, meta, hybrid, hybrid meta, and range-separated functionals, band theory, software, validation tests, and applications to spin states, magnetic exchange coupling, spectra, structure, reactivity, and catalysis, including molecules, clusters, nanoparticles, surfaces, and solids.

Abstract: The applications of copper (Cu) and Cu-based nanoparticles, which are based on the earth-abundant and inexpensive copper metal, have generated a great deal of interest in recent years, especially in the field of catalysis. The possible modification of the chemical and physical properties of these nanoparticles using different synthetic strategies and conditions and/or via postsynthetic chemical treatments has been largely responsible for the rapid growth of interest in these nanomaterials and their applications in catalysis. In addition, the design and development of novel support and/or multimetallic systems (e.g., alloys, etc.) has also made significant contributions to the field. In this comprehensive review, we report different synthetic approaches to Cu and Cu-based nanoparticles (metallic copper, copper oxides, and hybrid copper nanostructures) and copper nanoparticles immobilized into or supported on various support materials (SiO2, magnetic support materials, etc.), along with their applications i...