A gamma-alumina-supported silver cluster catalyst--Ag/Al(2)O(3)--has been shown to act as an efficient heterogeneous catalyst for oxidant-free alcohol dehydrogenation carbonyl compounds at 373 K. The shows higher activity than conventional catalysts based on platinum group metals (PGMs) and can be recycled. systematic study the influence of particle size oxidation state species, combined with characterization by Ag K-edge XAFS (X-ray absorption fine structure) has established that clusters...

An optically inactive poly(4-carboxyphenyl isocyanide) (poly-1-H) changed its structure into the prevailing, one-handed helical upon complexation with active amines in dimethylsulfoxide (DMSO) and water, complexes show a characteristic induced circular dichroism polymer backbone region. Moreover, macromolecular helicity water aqueous organic solutions containing more than 50 vol % could be "memorized" even after complete removal of chiral (h-poly-1b-H), while that DMSO DMSO−water mixtures...

The size control of Ag into nanoclusters generates unique catalytic features on automotive emission and environmentally friendly organic reactions. Hydrogen-assisted selective reduction NO by hydrocarbons (H2–HC–SCR), which is one the promising technologies for removal in diesel engine exhausts, results formation clusters alumina or zeolites enhancement conversion N2. A mechanistic study using situUV-Vis, EXAFS, FT/IR revealed that promotion partial oxidation active oxygen species essential...

The key reactive sites in the selective catalytic reduction (SCR) of NO using ammonia (NH3–SCR) are Cu(II)/Cu(I) ammine complexes encapsulated within zeolite catalysts. reaction intermediate important CuI → CuII reoxidation step has been proposed as dicopper species. However, obtaining definitive spectroscopic probe for under NH3–SCR remains a quite challenging subject. Here we report evidence efficient generation over Cu-ion-exchanged zeolites. state Cu ion condition was analyzed...

Hydrogen storage and transportation are pivotal for a hydrogen- carbon-neutral society, yet current approaches face considerable limitations in efficiency cost, which typically related to catalyst design. Alloying trace amount of Pt on supported Co nanoparticles has emerged as an innovative design that leads substantial reduction the precious metal used catalytic hydrogenation toluene (TOL) methylcyclohexane (MCH), is important aspect hydrogen transportation. However, because difficulty...

Achieving complete substrate specificity through multiple interactions like an enzyme is one of the ultimate goals in catalytic studies. Herein, we demonstrate that between CeO2 surface and substrates are origin substrate-specific hydration nitriles water by CeO2, which exclusively applicable to with a heteroatom (N or O) adjacent α-carbon CN group but not other nitriles. Kinetic studies reveal reduces entropic barrier (TΔS‡) for reaction former reactive substrate, leading 107-fold rate...

Hydrogenation of toluene (TOL) to methylcyclohexane (MCH) is one the hydrogen carrier systems desired for social integration. Supported Pt nanoparticle catalysts are effective this application. However, rare, expensive, and in short supply, limiting its practical applications. Therefore, key issue TOL hydrogenation how substantially reduce amount required catalyst. Because a specific ensemble atoms, that dominantly formed on surface nanoparticle, achieving higher catalytic performance, there...

Adsorption states and photochemistry of methane deuterated on a Pt(111) surface have been investigated by measuring temperature-programmed desorption spectra, x-ray photoelectron work function changes, angle-resolved time-of-flight distributions desorbed species. Methane weakly adsorbed the at 40 K is dissociated to methyl hydrogen fragments with laser irradiation 193 nm. This remarkably different from in gas phase where photodissociation takes place only λ<145 While photofragments...

Can't keep me down: Silver nanoclusters (NCs), formed by spontaneous atomic-level dispersion of non-nano silver onto Al2O3 surface, show self- regenerative properties during redox aging above 900 °C and, consequently, higher activity than state-of-the-art CO oxidation catalysts after the aging. Size-dependence and DFT calculation indicate that Ag atoms at corner/edge sites are active site NCs. Detailed facts importance to specialist readers published as "Supporting Information". Such...

We successfully synthesized a Fe/ZSM-5 catalyst enabling conversion of methane to C1 oxygenates in record yields, and demonstrated that the fraction single Fe cation, as well Al distribution, are powerful activity descriptors.

The hydrogen molecule chemisorption on the low coordination or corner site of MgO surface has been studied with ab initio method, adopting (MgO)4 cluster as model. effect basis functions and correlation have examined. Two physisorbed complexes found; one is an end-on complex oxygen other a side-on Mg site. These are led to common transition state (TS) then dissociative product. A substantial polarization charges in takes place at TS, from where proceeds ionically. best estimates energies...

Carbon monoxide (CO) molecules are attracting attention as capping agents that control the structure of metal nanoparticles. In this study, we aimed to shape and surface Pd particles by reducing supported precursor with CO. The reduction nanoparticles CO promoted exposure step sites generated spherical concave-tetrahedral on carbon SiO2 supports. On other hand, conventional H2-reduced show a flattened shape. preferential adsorbed was density functional theory-calculated energy Wulff...

We successfully developed a Pt single atom alloyed sub-1 nm thick Fe overlayer on Cu nanoparticles capable of catalyzing MCH dehydrogenation with the H 2 -evolution rate per mass at least 133 times higher than that state-of-the-art catalysts.

Methane on Pt(111) dissociates or desorbs under irradiation by 193-nm photons. The polarization-dependent cross sections of the photochemical processes have been measured as a function incident angle using postirradiation temperature-programmed desorption. incident-angle dependence obtained with $p$ polarization substantially deviates from that substrate absorbance. This clearly indicates an adsorbate-localized excitation plays important role in photochemistry methane.

Nanoparticles (NPs) supported on metal oxides exhibit high catalytic activities for various reactions. The shape and oxidation state of such NPs, which are related to the activity, often determined by support. Herein, we conducted a density functional theory study isolated silver (Ag) NPs two types Ag-NPs gamma-aluminum oxide (γ-Al2O3). First, carbon monoxide (CO) adsorption Ag was investigated decahedra (D5h ), icosahedra (Ih cuboctahedra (Oh ) sizes. Ih Oh showed moderate size dependence,...

Abstract Ni@Ag core–shell nanoparticles supported on SiO2 were prepared by a galvanic replacement reaction between Ni and Ag at low temperature (213 K). The catalyst showed higher catalytic activity for CO oxidation than monometallic catalysts as well Ni–Ag bimetallic conventional impregnation method.

Using (MgO)4, (MgO)6, and (MgO)8 clusters as models of the MgO surface, structures energies H2 chemisorption on various pair sites are studied with ab initio molecular orbital calculations. The effect Madelung potential energetics is also studied. energy not very sensitive to cluster size used in calculation. It however depends strongly coordination numbers Mg O at site, decreases following order: valley site ≫Mg3c–O3c≫Mg4c–O3c≳Mg3c–O4c site. Mg3c–O3c bonding, whereas Mg4c–O3c Mg3c–O4c only...