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Embedding energetically stable single metal atoms in the surface of Pt nanocatalysts exposed to varied temperature (T) and hydrogen pressure (P) could open up new possibilities in selective and dynamical engineering of alloyed Pt catalysts, particularly interesting for hydrogenation reactions. In this work, an environmental segregation energy model is developed to predict the stability and the surface composition evolution of 24 Metal M-promoted Pt surfaces (with M: Cu, Ag, Au, Ni, Pd, Co, Rh and Ir) under varied T and P. Counterintuitive to expectations, the results show that the more reactive alloy component (i.e., the one forming the strongest chemical bond with the hydrogen) is not the one that segregates to the surface. Moreover, using DFT-based Multi-Scaled Reconstruction (MSR) method and by extrapolation of M-promoted Pt nanoparticles (NPs), the shape dynamics of M-Pt are investigated under the same ranges of T and P. The results show that under low hydrogen pressure and high temperature ranges, Ag and Au—single atoms (and Cu to a less extent) are energetically stable on the surface of truncated octahedral and/or cuboctahedral shaped NPs. This indicated that coinage single-atoms might be used to tune the catalytic properties of Pt surface under hydrogen media. In contrast, bulk stability within wide range of temperature and pressure is predicted for all other M-single atoms, which might act as bulk promoters. This work provides insightful guides and understandings of M-promoted Pt NPs by predicting both the evolution of the shape and the surface compositions under reaction gas condition. [ABSTRACT FROM AUTHOR]

The reactivity and structure of several platinum nanoparticles adsorbed on a (5,5) CNT have been studied on the basis of DFT. Changes in the materials reactivity due to charge redistribution and chemical and geometrical factors were observed. Additionally, we have investigated the nanoparticles reactivity for water dissociation and found a competing behavior between the particle structure and charge accumulation, which influences the decrease in the activation energies of the process and provides a deeper understanding of the reaction path and the material behavior as well. [ABSTRACT FROM AUTHOR]

The reactivity of benzimidazol-2-ylidenes with respect to gold nanoparticles (AuNPs) has been investigated using a combined experimental and computational approach. First, the grafting of benzimidazol-2-ylidenes bearing benzyl groups on the nitrogen atoms is described, and comparisons are made with structurally similar N-heterocyclic carbenes (NHCs) bearing other N-groups. Similar reactivity was observed for all NHCs, with 1) the erosion of the AuNPs under the effect of the NHC and 2) the formation of bis(NHC) gold complexes. DFT calculations were performed to investigate the modes of grafting of such ligands, to determine adsorption energies, and to rationalize the spectroscopic data. Two types of computational models were developed to describe the grafting onto large or small AuNPs, with either periodic or cluster-type DFT calculations. Calculations of NMR parameters were performed on some of these models, and discussed in light of the experimental data. [ABSTRACT FROM AUTHOR]

A DFT-based molecular model for imidazolium-silica-based nanoparticle networks (INNs) is presented. The INNs were synthesized and characterized by using small-angle X-ray scattering (SAXS), NMR spectroscopy, and theoretical ab initio calculations. 11B and 31P HETCOR CP MAS experiments were recorded. Calculated 19F NMR spectroscopy results, combined with the calculated anion-imidazolium (IM) distances, predicted the IM chain density in the INN, which was also confirmed from thermogravimetric analysis/mass spectrometry results. The presence of water molecules trapped between the nanoparticles is also suggested. First considerations on possible π-π stacking between the IM rings are presented. The predicted electronic properties confirm the photoluminescence emissions in the correct spectral domain. [ABSTRACT FROM AUTHOR]

This feature article gives an overview of the research performed on ionic nanoparticle networks (INNs). These INNs are hybrid materials consisting of inorganic nanoparticles and ionic linkers, such as imidazolium, bisimidazolium or pyridinium. The synthesis and properties of INNs, for catalysis or sensorics, are presented. At each step INN materials are compared to other hybrid materials of similar composition such as ionogels or suspensions of imidazolium modified nanoparticles. [ABSTRACT FROM AUTHOR]

In this study, bitumen modified by fumed silica nanoparticles was characterized through dynamic shear rheometer tests, scanning electron microscopy, and Fourier transform infrared spectroscopy. The fumed silica nanoparticles were used in three different ratios, i.e., 0.1, 0.2 and 0.3 wt.-% of bitumen. Specifically, the modified bitumen characteristics were studied after laboratory aging by analyzing the chemical composition and rheological properties. From the determination of oxidation degree and carbonyl index it was found that the resistance of the modified bitumen to ultraviolet aging was improved with the increasing nanoparticle content. In bitumen modified by fumed silica nanoparticles, the nanoparticles were well dispersed. Moreover, the results illustrated that the bitumen properties were improved, and the improvement effect of 0.1 wt.-% fumed silica nanoparticles was more distinct than the higher concentrations. [ABSTRACT FROM AUTHOR]

The calculated Au38 cluster is represented in the middle of the cover picture, coated by the N ‐ heterocyclic carbenes (NHCs) presented in the paper. The falling binary code “01” illustrates that the Au38 clusters are issued from DFT calculations. Molecular bis(NHC) gold complexes obtained from the functionalization of the particles are represented around the cluster. An experimental 1H NMR solid ‐ state spectrum is shown in the lower part of the cover to remind the reader that the study combines experimental and computational approaches. More information can be found in the Full Paper by F. Tielens, F. Remacle, S. Richeter et al. on page 10446 ff. [ABSTRACT FROM AUTHOR]

Ag-containing semiconductors have gained great attention due to their outstanding visible light-responsive photocatalytic properties. In the current work, silver oxide (Ag 2 O) nanoparticles were in situ self-grown on the surface of AgZr 2 (PO 4) 3 NASICON-type material using sodium hydroxide-assisted precipitation to form an Ag 2 O/Ag 1-x Na x Zr 2 (PO 4) 3 nanocomposite. The crystalline structures, morphological observations, elemental composition, and optical properties of the prepared product were carried out using various characterization methods. The photocatalytic performance of Ag 2 O/Ag 1-x Na x Zr 2 (PO 4) 3 has then been explored in the decomposition of methyl orange (MO) wastewater pollutant under visible light. The obtained photocatalyst exhibited excellent decomposition efficiency (95.08 %, k = 0.0303 min−1) for MO removal within 60 min. In addition, the prepared nanocomposite exhibited proper reusability even after five successive cycles without any significant loss in photocatalytic activities. Furthermore, a simple catalyst regeneration strategy based on hydrogen peroxide (H 2 O 2) was adopted, revealing that the spent photocatalyst can achieve nearly total self-regeneration to the initial AgZr 2 (PO 4) 3 material. [Display omitted] • Self-supported Ag 2 O NPs on AgZr 2 (PO 4) 3 material via NaOH treatment. • The reaction between AgZr 2 (PO 4) 3 and NaOH also gives rise to Ag 1-x Na x Zr 2 (PO 4) 3. • Ag 2 O NPs/Ag 1-x Na x Zr 2 (PO 4) 3 demonstrated good photocatalytic performance for dye degradation. • The photocatalytic activity was ascribed to the formation of Ag0 in situ. • AgZr 2 (PO 4) 3 initial phase can be regenerated through a simple treatment with H 2 O 2. [ABSTRACT FROM AUTHOR]

Review: 78 refs. [ABSTRACT FROM AUTHOR]

The thorough understanding of the adsorption mechanism of phosphate on hydrous ferric oxides is necessary to deal with the environmental issues related to high phosphate concentrations in soils and open water. In this work, we consider three different adsorption geometries (monodentate and bidentate chemisorption and physisorption) and calculate the adsorption geometries and related adsorption energies at optPBE-vdW level. Using the Maxwell-Boltzmann distribution, it is estimated that about 83% of the phosphate molecules is in a monodentate chemisorption configuration, while 17% is physisorbed. Furthermore, theoretical infra-red spectra are obtained and compared to equivalent experimental spectra, supporting the conclusion that mainly monodentate chemisorption and physisorption occur. Most interestingly, a weighed infra-red spectrum is then calculated, using the weights from the Maxwell-Boltzmann distribution, showing a very good comparison with the experimental spectra. Image 1 • Phosphate molecules adsorb majority in monodentate configuration on goethite. • Theoretical and experimental IR spectra support that mainly monodentate adsorption occur. • Goethite nanoparticules' morphology has been predicted in the presence of phosphate. [ABSTRACT FROM AUTHOR]