Editorial: Nanocatalysis

Catalysis by metal and metal oxide nano-sized (and smaller, sub-nanometer) structures such as clusters and nanoparticles represents a consolidated field in chemistry. Shaping metals into the (sub)nano regime allows one to modulate both quantitatively (surface-to-volume ratio) and qualitatively (types of facets and surface atom coordination) the catalytically active regions with respect to extended systems. This increased freedom has been widely exploited in the past to improve/maximize the efficiency and selectivity of many catalytic processes of fundamental interest and industrial relevance. Major challenges however exist in the field, which are not yet fully addressed. The transition from carbon-based to green energy production, storage, and use and the environmental implications in fact requires the development of efficient and selective catalytic processes at lower temperature and less extreme conditions than those currently known e.g. in the conversion of petroleum and biomass, electrochemical and/or photochemical water splitting and fuel cells, CO_2 reduction to fuels, NH_3 synthesis etc

NEAR Gamma Ray Spectrometer Characterization and Repair

This report covers the work completed in the third year of the contract. The principle activities during this period were (1) the characterization of the NEAR 2 Gamma Ray Spectrometer using a neutron generator to generate complex gamma ray spectra and a large Ge Detecter to identify all the major peaks in the spectra; (2) the evaluation and repair of the Engineering Model Unit of the Gamma Ray Spectrometer for the NEAR mission; (3) the investigation of polycapillary x-ray optics for x-ray detection; and (4) technology transfer from NASA to forensic science

Editorial: Nanocatalysis

Catalysis by metal and metal oxide nano-sized (and smaller, sub-nanometer) structures such as clusters and nanoparticles represents a consolidated field in chemistry. Shaping metals into the (sub)nano regime allows one to modulate both quantitatively (surface-to-volume ratio) and qualitatively (types of facets and surface atom coordination) the catalytically active regions with respect to extended systems. This increased freedom has been widely exploited in the past to improve/maximize the efficiency and selectivity of many catalytic processes of fundamental interest and industrial relevance. Major challenges however exist in the field, which are not yet fully addressed. The transition from carbon-based to green energy production, storage, and use and the environmental implications in fact requires the development of efficient and selective catalytic processes at lower temperature and less extreme conditions than those currently known e.g. in the conversion of petroleum and biomass, electrochemical and/or photochemical water splitting and fuel cells, CO_2 reduction to fuels, NH_3 synthesis etc

Perspective: Size selected clusters for catalysis and electrochemistry

Size-selected clusters containing a handful of atoms may possess noble catalytic properties different from nano-sized or bulk catalysts. Size- and composition-selected clusters can also serve as models of the catalytic active site, where an addition or removal of a single atom can have a dramatic effect on their activity and selectivity. In this perspective, we provide an overview of studies performed under both ultra-high vacuum and realistic reaction conditions aimed at the interrogation, characterization, and understanding of the performance of supported size-selected clusters in heterogeneous and electrochemical reactions, which address the effects of cluster size, cluster composition, cluster–support interactions, and reaction conditions, the key parameters for the understanding and control of catalyst functionality. Computational modeling based on density functional theory sampling of local minima and energy barriers or ab initio molecular dynamics simulations is an integral part of this research by providing fundamental understanding of the catalytic processes at the atomic level, as well as by predicting new materials compositions which can be validated in experiments. Finally, we discuss approaches which aim at the scale up of the production of well-defined clusters for use in real world applications

Pd(n)Ag(4-n) and Pd(n)Pt(4-n) clusters on MgO (100) : a density functional surface genetic algorithm investigation

Global optimisation of catalytically relevant noble metal mono and bimetallic clusters is performed directly on an MgO substrate with DFT. Charge is distributed locally upon the cluster, providing a means to atomically control binding and reaction sites, as found for CO molecules on Pd/Ag/Pt.</p

Nanoassemblies of ultrasmall clusters with remarkable activity in carbon dioxide conversion into C1 fuels

Cu nanoassemblies formed transiently during reaction from size-selected subnanometer Cu4 clusters supported on amorphous OH-terminated alumina convert CO2 into methanol and hydrocarbons under near-atmospheric pressure at rates considerably higher than those of individually standing Cu4 clusters. An in situ characterization reveals that the clusters self-assemble into 2D nanoassemblies at higher temperatures which then disintegrate upon cooling down to room temperature. DFT calculations postulate a formation mechanism of these nanoassemblies by hydrogen-bond bridges between the clusters and H2O molecules, which keep the building blocks together while preventing their coalescence