Ceria (CeO2) is being increasingly used as support of metallic nanoparticles in catalysis due to its unique redox properties. Shedding light into the nature of the strong metal support interaction (SMSI) effect in CeO2-containing catalysts is important since it has a strong influence on the catalytic properties of the system. In this work, Cu/CeO2 and Ni/CeO2 nanoparticles are characterized when submitted to a reduction treatment at 500 °C in H2 atmosphere with a combination of in situ (XAS – X-ray absorption spectroscopy and time-resolved XAS) and ex situ (TEM – transmission electron microscopy and XPS - X-ray photoelectron spectroscopy) techniques. The existence of a capping layer decorating the Ni/CeO2 nanoparticles after the reduction treatment is shown, representing evidence for the SMSI effect. The kinetics of the SMSI occurrence is elucidated. It is proposed that the electronic factor of the SMSI effect has a strong influence on the reduction properties of the Ni nanoparticles supported on CeO2, decreasing its reduction temperature if compared to nonsupported Ni nanoparticles. The same phenomenon is not observed for Cu/CeO2 nanoparticles, where there is no evidence for the SMSI effect, and no changes on the reduction properties between supported and nonsupported Cu nanoparticles are observed.

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The controllable growth of vertically aligned ZnO nanowires using a simple vapour deposition method system is reported. The growth properties are studied as a function of the thickness of the Au catalyst layer, total pressure, deposition temperature and oxygen partial pressure. The experiments indicate the existence of five main zones of growth. The zone in which the aligned wires grow varies according to the pressure, temperature and oxygen partial pressure. A specific level of low supersaturation of Zn and oxygen vapour are both necessary to ensure the correct rate of growth, which then leads to having thin and densely aligned wires. The growth kinetics are discussed in terms of the interdependent variables. It was found that the diameter and density of the nanowires is controlled mostly by the growth temperature and pressure. The zone with the most aligned nanowires with the highest aspect ratio was found to be at 5 mbar in a temperature range of 860-800 • C with a flow of 27 sccm of a N 2 /O 2 mixture.

The strong metal–support interaction (SMSI) effect plays a central role in catalysis by decreasing the catalytic activity or even improving it in some specific cases. In spite of the intense research, a detailed description of the SMSI effect in CeO2-based catalysts is still missing. In this work, Cu x Ni1–x /CeO2 (0 < x < 1) nanoparticles were exposed to a reduction treatment in a H2 atmosphere followed by an oxidation treatment in a CO2 atmosphere, both at 500 °C, and studied by using state-of-the-art techniques (in situ time-resolved X-ray absorption near edge structure (XANES) and near ambient pressure X-ray photoelectron spectroscopy (NAP-XPS)). It was observed the migration of Cu (Ni) atoms toward the surface of Cu–Ni bimetallic nanoparticles during reduction (oxidation) treatments. The core–shell-like structure is dependent on the Cu/Ni ratio. It was observed the existence of a capping layer from the support (CeO2–x ) surrounding the metallic nanoparticles after reduction treatment (characteristic of the SMSI effect) in some specific cases, depending on the Cu/Ni ratio as well. The surface of the nanoparticles presenting the SMSI effect is recovered to the initial state after exposure to the CO2 atmosphere. Moreover, the nature of the SMSI effect was elucidated. The capping layer interacts with the Cu and Ni atoms via Ce 3d10 O 2p6 Ce 4f0 and Ce 3d10 O 2p6 Ce 4f1 initial states, depending on the case studied. As a consequence of the SMSI effect, the Cu atoms of the nanoparticles reduce at lower temperature than similar nanoparticles that do not present the SMSI effect. Therefore, the decrease in reduction temperature is directly related to the interaction between the CeO2–x capping layer and Cu and Ni atoms.

Hybrid organosilicas prepared by sol-gel processes using 1-n-butyl-3-(3-trimethoxysilylpropyl)-imidazolium cations associated with hydrophilic and hydrophobic anions can be easily decorated with well dispersed and similar size (1.8-2.1 nm) Pd nanoparticles (Pd-NPs) by simple sputtering-deposition. Higher Pd concentration at the surface compared to the deeper region is obtained in the supports with smaller pore diameter (containing hydrophobic ILs) than in supports with the largest pore diameter (containing hydrophilic ILs). The IL hydrophobicity plays a central role in the hydrogenation of dienes by controlling the diene access to NP surface active sites.

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Crystallographically preferred oriented porous Ta 3 N 5 nanotubes (NTs) were synthesized by thermal nitridation of vertically oriented, thick-walled Ta 2 O 5 NTs, strongly adhered to the substrate. The adherence on the substrate and the wall thickness of the Ta 2 O 5 NTs were finetuned by anodization, thereby helping to preserve their tubular morphology for nitridation at higher temperatures. Samples were studied by scanning electron microscopy, high-resolution electron microscopy, X-ray diffraction, Rietveld refinements, ultraviolet−visible spectrophotometry, X-ray photoelectron spectroscopy, photoluminescence spectra, and electrochemical techniques. Oxygen content in the structure of porous Ta 3 N 5 NTs strongly influenced their photoelectrochemical activity. Structural analyses revealed that the nitridation temperature has crystallographically controlled the preferential orientation along the (110) direction, reduced the oxygen content in the crystalline structure and the tubular matrix, and increased the grain size. The preferred oriented porous Ta 3 N 5 NTs optimized by the nitridation temperature presented an enhanced photocurrent of 7.4 mA cm −2 at 1.23 V vs RHE under AM 1.5 (1 Sun) illumination. Hydrogen production was evaluated by gas chromatography, resulting in 32.8 μmol of H 2 in 1 h from the pristine porous Ta 3 N 5 NTs. Electrochemical impedance spectroscopy has shown an effect of nitridation temperature on the interfacial charge transport resistance at the semiconductor−liquid interface; however, the flat band of Ta 3 N 5 NTs remained unchanged.

Unsupported bimetallic Co/Pt nanoparticles (NPs) of 4.4 ± 1.9 nm can be easily obtained by a simple reaction of [bis(cylopentadienyl)cobalt(ii)] and [tris(dibenzylideneacetone) bisplatinum(0)] complexes in 1-n-butyl-3-methylimidazolium hexafluorophosphate IL at 150 °C under hydrogen (10 bar) for 24 h. These bimetallic NPs display core-shell like structures in which mainly Pt composes the external shell and its concentration decreases in the inner-shells (CoPt3@Pt-like structure). XPS and EXAFS analyses show the restructuration of the metal composition at the NP surface when they are subjected to hydrogen and posterior H2S sulfidation, thus inducing the migration of Co atoms to the external shells of the bimetallic NPs. Furthermore, the isolated bimetallic NPs are active catalysts for the Fischer-Tropsch synthesis, with selectivity for naphtha products.