Search

Development of N-doped Pd/C catalysts for hydrogen production from gas-phase formic acid is a challenge. To elucidate the efficient routes of nitrogen insertion on the surface of a mesoporous carbon support, the latter was treated with melamine (Mel), dicyandiamide or NH 3 at 673 and 823 K. Pyrolysis of the melamine/carbon mixture taken in a 1:2 ratio provides an increase in the reaction rate by a factor of 5. The inserted N-sites strongly interact with Pd leading to the formation of highly dispersed Pd nanoparticles (∼1.6 nm) and active atomically dispersed Pd2+ species. With a further increase of the Mel/C ratio, the number of surface N-sites decreases due to occupation of carbon support pores with a g–C 3 N 4 –type residue. This provides a decrease in the Pd dispersion leading to lower reaction rates. Therefore, melamine is an efficient N precursor. The considered synthesis of N-doped catalysts could be scaled. [Display omitted] • Pd/N–C catalysts were studied in hydrogen production from gaseous formic acid. • Melamine, dicyandiamide and NH 3 were used to incorporate N species into C support. • At Mel/C ratio of 1:2 the reaction rate was maximal and increased by a factor of 5. • Emission of by-product CO was decreased by a factor of 4. • Pd was present as nanoparticles (∼1.6 nm) and atomic Pd2+ species. [ABSTRACT FROM AUTHOR]

The work reported here was aimed at determining differences in redox properties of simple and double oxides. Comparison between the reduction of double oxides (Mn,Co)3O4 and simple oxides Co3O4 and Mn3O4 was performed using in situ X-ray diffraction (XRD), temperature-programmed reduction (TPR) and transmission electron microscopy (TEM). The double oxides with a ratio of cations Mn : Co = 1 : 1 were prepared by the coprecipitation method and contained a mixture of 50% MnCo2O4 and 50% CoMn2O4. It was shown that the mechanism of reduction of double oxides with hydrogen differs significantly from the processes occurring on simple oxides. For simple cobalt and manganese oxides, transformations Co3O4→ CoO → Co and Mn3O4→ MnO are observed under a hydrogen atmosphere. The reduction of mixed-metal oxides occurs in two steps. In the first step, at 300–450 °C, (Mn,Co)3O4 transforms to (Mn,Co)O solid solutions. In situ XRD under isothermal conditions illustrates that Co-rich Co2MnO4 oxide starts to be reduced to Co0.6Mn0.4O first, and then Mn-rich Mn2CoO4 passes into Mn0.6Co0.4O. In the second step, at 450–700 °C, the reduction of solid solutions (Mn,Co)O to metallic cobalt Co and MnO proceeds. Again, the reduction begins with transformation of Co-rich oxide with the Co0.6Mn0.4O structure. The temperature of appearance of the intermediate phase (Mn,Co)O shifts to the higher values as compared to those observed for CoO, and to lower temperatures as compared to MnO during simple oxide reduction. [ABSTRACT FROM AUTHOR]

A template method for synthesis of B-doped graphene-like carbon nanomaterial (B-graphene-like carbon) with high surface area has been developed. In this method, magnesium oxide is used as a template where a carbon layer doped with boron atoms is deposited. Magnesium oxide carbonization was performed in an autoclave at 600 °C and 5 atm pressure using phenylboronic acid (FBA) dissolved in an ethanol-acetone mixture. Then, magnesium oxide from the С—B/MgO composite was dissolved in hydrochloric acid. The obtained B- graphene-like carbon was studied by IR spectroscopy, electron microscopy, XPS methods and quantum chemical calculations. B-graphene-like carbon contains 3–6 carbon layers and 0.2 wt% B. Structure of carbon net with embedded boron fragment has been proposed as the result of performed studies. [ABSTRACT FROM AUTHOR]

A novel ultra-high-entropy rare earth orthoferrite (UHE REO) of Sc1/16Y1/16La1/16Ce1/16Pr1/16Nd1/16Sm1/16Eu1/16Gd1/16Tb1/16Dy1/16Ho1/16Er1/16Tm1/16Yb1/16Lu1/16FeO3 nominal composition was successfully synthesized for the first time through a simple and efficient solution combustion approach. PXRD, Raman, and 57Fe Mössbauer spectroscopy confirmed the high chemical and phase purity of the synthesized UHE REO (hereafter denoted as ΣREFeO3), which belonged to the Pnma space group, typical of the perovskite-like rare earth orthoferrites. Despite the fact that the main X-ray reflections, vibration modes, and spectral Mössbauer components unambiguously indicate the single-phase nature of the sample, the results of SEM and TEM make it possible to establish the presence of a main (about 50 nm) and a minor ultrafine (about 10 nm) fraction of ΣREFeO3 nanoparticles. The bimodal size distribution of nanoparticles was also reflected in the magnetic behavior of this substance: the presence of several sextet components in the Mössbauer spectra, the hard single-domain magnetic nature of the main fraction of 50 nm UHE REO nanoparticles, and the superparamagnetic state of the minor fraction of 10 nm UHE REO nanoparticles. Thus, the unusual features of nanostructured ΣREFeO3 can potentially be used for the creation of new generations of transformers, magnetic memory systems, magnetic screens, radio devices, etc. [ABSTRACT FROM AUTHOR]

The effect of support on the performance of Pd1Ag10/Al2O3 and Pd1Ag10/CeO2–ZrO2 catalysts in the selective hydrogenation of diphenylacetylene (DPA) was studied. Characterization of the catalyst by DRIFTS-CO and HRTEM revealed the formation of a PdAg single-atom alloy (SAA) structure on the surface of PdAg nanoparticles, with Pd1 sites isolated by Ag atoms. It was found that the use of CeO2–ZrO2 as a carrier makes it possible to increase the activity of the Pd1Ag10 catalyst by a factor of three without loss of selectivity compared to the reference Pd1Ag10/Al2O3. According to the HRTEM data, this catalytic behavior can be explained by an increase in the dispersion of Pd1Ag10/CeO2–ZrO2 compared to its Pd1Ag10/Al2O3 counterpart. As evidenced by DRIFTS-CO data, the high selectivity of the Pd1Ag10/CeO2–ZrO2 sample presumably stems from the stability of the structure of isolated Pd1 sites on the surface of SAA Pd1Ag10/CeO2–ZrO2. [ABSTRACT FROM AUTHOR]

Photocatalysts based on g-C3N4 have been investigated in the CO2 reduction reaction under visible light irradiation (λ = 397, 427, 452 nm). Photocatalysts were prepared by melamine calcination at 500–600 °C with further platinum deposition (0.1–1.0 wt.%). The effect of the preparation conditions of g-C3N4 and the method of platinum deposition on the physicochemical properties and activity of photocatalysts was studied. The photocatalysts were investigated by X-ray photoelectron spectroscopy, X-ray absorption spectroscopy, X-ray diffraction, high resolution transmission electron microscopy, UV-Vis spectroscopy, and low temperature nitrogen adsorption techniques. It has been found that the efficiency of CO2 reduction is governed by the surface area of g-C3N4 and the presence of platinum in the metallic state, while the optimal content of platinum is 0.5 wt. %. The highest rate of CO2 reduction achieved over Pt/g-C3N4 photocatalyst is 13.2 µmol h−1 g−1 (397 nm), which exceeds the activity of pristine g-C3N4 by 7 times. The most active photocatalysts was prepared by calcining melamine in air at 600 °C, followed by modification with platinum (0.5 wt.%). [ABSTRACT FROM AUTHOR]

The catalytic utilization of chlorine-organic wastes remains of extreme importance from an ecological point of view. Depending on the molecular structure of the chlorine-substituted hydrocarbon (presence of unsaturated bonds, intermolecular chlorine-to-hydrogen ratio), the features of its catalytic decomposition can be significantly different. Often, 1,2-dichloroethane is used as a model substrate. In the present work, the catalytic decomposition of trichloroethylene (C2HCl3) over microdispersed 100Ni and 96Ni-4W with the formation of carbon nanofibers (CNF) was studied. Catalysts were obtained by a co-precipitation of complex salts followed by reductive thermolysis. The disintegration of the initial bulk alloy driven by its interaction with the reaction mixture C2HCl3/H2/Ar entails the formation of submicron active particles. It has been established that the optimal activity of the pristine Ni catalyst and the 96Ni-4W alloy is provided in temperature ranges of 500–650 °C and 475–725 °C, respectively. The maximum yield of CNF for 2 h of reaction was 63 g/gcat for 100Ni and 112 g/gcat for 96Ni-4W catalyst. Longevity tests showed that nickel undergoes fast deactivation (after 3 h), whereas the 96Ni-4W catalyst remains active for 7 h of interaction. The effects of the catalyst's composition and the reaction temperature upon the structural and morphological characteristics of synthesized carbon nanofibers were investigated by X-ray diffraction analysis, Raman spectroscopy, and electron microscopies. The initial stages of the carbon erosion process were precisely examined by transmission electron microscopy coupled with elemental mapping. The segmented structure of CNF was found to be prevailing in a range of 500–650 °C. The textural parameters of carbon product (SBET and Vpore) were shown to reach maximum values (374 m2/g and 0.71 cm3/g, respectively) at the reaction temperature of 550 °C. [ABSTRACT FROM AUTHOR]

Mixed Ni-Al oxide catalytic precursors with different elemental ratios (20, 50, and 80 wt.% Ni0) were synthesized using green supercritical antisolvent co-precipitation (SAS). The obtained oxide precursors and metal catalysts were characterized in detail by X-ray diffraction (XRD) analysis, atomic pair distribution function (PDF) analysis, CO adsorption, and high-resolution transmission electron microscopy (HRTEM). It was found that the composition and structure of the Ni-Al precursors are related to the Ni content. The mixed Ni1−xAlxO oxide with NiO-based crystal structure was formed in the Ni-enriched sample, whereas the highly dispersed NiAl2O4 spinel was observed in the Al-enriched sample. The obtained metal catalysts were tested in the process of anisole H2-free hydrogenation. 2-PrOH was used as a hydrogen donor. The catalyst with 50 wt.% Ni0 demonstrated the highest activity in the hydrogenation process. [ABSTRACT FROM AUTHOR]

Synthesis and characterization of spherulite-like nanocrystalline titania with rutile structure (r-TiO2) are described herein. The r-TiO2 particles were synthesized via the convenient and low-cost hydrothermal treatment of TiO(C6H6O7) titanyl citrate. The r-TiO2 spherulites are micron-sized agglomerates of rod-shaped nanocrystals with characteristic sizes of 7(±2) × 43(±10) nm, oriented along (101) crystallographic direction, and separated by micropores, as revealed by SEM and TEM. PXRD and Raman spectroscopy confirmed the nanocrystalline nature of r-TiO2 crystallites. BET analysis showed a high specific surface area of 102.6 m2/g and a pore volume of 6.22 mm3/g. Photocatalytic performances of the r-TiO2 spherulites were investigated for the processes of methyl violet (MV) degradation in water and hydrogen evolution reaction (HER) in aqueous solutions of ethanol. The (MV) degradation kinetics was found to be first-order and the degradation rate coefficient is 2.38 × 10−2 min−1. The HER was performed using pure r-TiO2 spherulites and nanocomposite r-TiO2 spherulites with platinum deposited on the surface (r-TiO2/Pt). It was discovered that the r-TiO2/Pt nanocomposite has a 15-fold higher hydrogen evolution rate than pure r-TiO2; their rates are 161 and 11 nmol/min, respectively. Thus, the facile synthesis route and the high photocatalytic performances of the obtained nanomaterials make them promising for commercial use in such photocatalytic processes as organic contamination degradation and hydrogen evolution. [ABSTRACT FROM AUTHOR]

Double oxides with the structure of the Ruddlesden–Popper (R-P) layered perovskite An+1BnO3n+1 attract attention as materials for various electrochemical devices, selective oxygen-permeable ceramic membranes, and catalytic oxidative reactions. In particular, Sr2TiO4 layered perovskite is considered a promising catalyst in the oxidative coupling of methane. Our high-resolution transmission electron microscopy (HRTEM) studies of Sr2TiO4 samples synthesized using various methods have shown that their structure often contains planar defects disturbing the periodicity of layer alternation. This is due to the crystal-chemical features of the R-P layered perovskite-like oxides whose structure is formed by n consecutive layers of perovskite (ABO3)n in alternating with layers of rock-salt type (AO) in various ways along the c crystallographic direction. Planar defects can arise due to a periodicity violation of the layers alternation that also leads to a violation of the synthesized phase stoichiometry. In the present work, a crystallochemical analysis of the possible structure of planar defects is carried out, structures containing defects are modeled, and the effect of such defects on the X-ray diffraction patterns of oxides of the A2BO4 type using Sr2TiO4 is established as an example. For the calculations, we used the method of constructing probabilistic models of one-dimensionally disordered structures. For the first time, the features of diffraction were established, and an approach was demonstrated for determining the concentration of layer alternation defects applicable to layered perovskite-like oxides of the A2BO4 type of any chemical composition. A relation has been established between the concentration of planar defects and the real chemical composition (nonstoichiometry) of the Sr2TiO4 phase. The presence of defects leads to the Ti enrichment of particle volume and, consequently, to the enrichment of the surface with Sr. The latter, in turn, according to the data of a number of authors, can serve as an explanation for the catalytic activity of Sr2TiO4 in the oxidative coupling of methane. [ABSTRACT FROM AUTHOR]

In this paper, the influence of surface modification on the characteristics and properties of AlN thin films on Si and glass-ceramics substrates is investigated. The surface modification was made at various parameters of argon cluster ions. By using XRD and Raman spectroscopy, it was shown that the obtained AlN films have a hexagonal structure with a characteristic direction of texturing along the c axis and slight deviations from it. A comparison of the AlN surface morphology obtained by atomic force microscopy before and after cluster processing was demonstrated. This demonstrated that the cluster ions with low energy per atom (E/N = 10 eV/atom) have a high efficiency of surface smoothing. A decrease in the intensity of the Raman peaks and an increase in their full-width after bombardment with cluster ions were found, which may be caused by a change in the physicochemical state of the surface. The optical properties, the quality of the boundaries, and the distribution map of the thickness of the functional layer of AlN were investigated by the methods of spectral and spatial resolution ellipsometry. By using the cross-sectional SEM, the direction of crystallite texturing was demonstrated. The influence of argon cluster ion bombardment on the stoichiometry of samples was analyzed by EDX spectroscopy. The results obtained demonstrate the efficiency of the cluster ion smoothing of polycrystalline thin films for microelectronics, particularly when creating surface acoustic wave resonators. [ABSTRACT FROM AUTHOR]

Two types of photocatalysts, 1%Pt/Cd1−xZnxS/g-C3N4 (x = 0.2–0.3) and Cd1−xZnxS/1%Pt/g-C3N4 (x = 0.2–0.3), were synthesized by varying the deposition order of platinum, and a solid solution of cadmium and zinc sulfides onto the surface of g-C3N4. The characterization of photocatalysts showed that, for 1%Pt/Cd1−xZnxS/g-C3N4, small platinum particles were deposited onto a solid solution of cadmium and zinc sulfides; in the case of Cd1−xZnxS/1%Pt/g-C3N4, enlarged platinum clusters were located on the surface of graphitic carbon nitride. Based on the structure of the photocatalysts, we assumed that, in the first case, type II heterojunctions and, in the latter case, S-scheme heterojunctions were realized. The activity of the synthesized samples was tested in hydrogen evolution from triethanolamine (TEOA) basic solution under visible light (λ = 450 nm). A remarkable increase in hydrogen evolution rate compared to single-phase platinized 1%Pt/Cd1−xZnxS photocatalysts was observed only in the case of ternary photocatalysts with platinum located on the g-C3N4 surface, Cd1−xZnxS/1%Pt/g-C3N4. Thus, we proved using kinetic experiments and characterization techniques that, for composite photocatalysts based on Cd1−xZnxS and g-C3N4, the formation of the S-scheme mechanism is more favorable than that for type II heterojunction. The highest activity, 2.5 mmol H2 g−1 h−1, with an apparent quantum efficiency equal to 6.0% at a wavelength of 450 nm was achieved by sample 20% Cd0.8Zn0.2S/1% Pt/g-C3N4. [ABSTRACT FROM AUTHOR]

The development of magnetoactive scaffolds based on piezoelectric polymers is of great interest due to their ability to exert a magnetoelectric effect, their flexibility, and biocompatibility in various prospective applications. This study describes fabrication of novel electrospun magnetoactive scaffolds based on poly(vinylidene fluoride- co -trifluoroethylene) [P(VDF-TrFE)] loaded with a high content (20 or 25 wt%) of magnetite nanoparticles modified by citric acid (Fe 3 O 4 -CA) and data on their structure and physicochemical, mechanical, and magnetic properties as well as a piezoelectric response. The suspension method gave a uniform nanoparticles' distribution in the electrospun scaffolds without any noticeable agglomeration. Raman and infrared spectroscopy and X-ray diffraction analysis indicated that the fabricated pure scaffolds and composite P(VDF-TrFE)/Fe 3 O 4 -CA scaffolds contain both piezoactive phases (β and γ). The composite scaffolds doped with 20 or 25 wt% of Fe 3 O 4 -CA nanoparticles were found to have the highest saturation magnetization, 12.7 and 14.1 emu/g, respectively, superior to that of other PVDF-Fe 3 O 4 –based magnetoactive scaffolds. Besides, the incorporation of 20 or 25 wt% of Fe 3 O 4 -CA nanoparticles substantially decreased total crystallinity of the piezopolymer scaffolds from 60.7% to 46.9% and 42.7%, respectively. Addition of 20 wt% of Fe 3 O 4 -CA nanoparticles also diminished ultimate strength and Young's modulus but improved elongation at break. Meanwhile, in composite P(VDF-TrFE)/Fe 3 O 4 -CA scaffolds loaded with 20 wt% of the magnetic filler, the piezoresponse was similar to that of pure P(VDF-TrFE) scaffolds. Such changes in properties are explained by the interaction between P(VDF-TrFE) polymer chains and the surface of Fe 3 O 4 -CA nanoparticles via hydrogen bonds and dipolar bonds. [Display omitted] • P(VDF-TrFE)/Fe 3 O 4 -CA scaffolds heavily loaded with Fe 3 O 4 -CA nanoparticles were fabricated by electrospinning. • The composite P(VDF-TrFE)/Fe 3 O 4 -CA magnetoactive scaffolds revealed the highest saturation magnetization (14.1 emu/g). • Piezoresponse of P(VDF-TrFE)/Fe 3 O 4 -CA was close to pure P(VDF-TrFE) scaffolds. [ABSTRACT FROM AUTHOR]

Reducing the size of a material with a first-order magnetic phase transition to the nanoscale results in a significant change in its physical properties. An example of this behaviour is the FeRh alloy. According to magnetometry results, the nanoparticles of this alloy do not show a transition from the antiferromagnetic to the ferromagnetic state near room temperature. In this work we have measured the magnetic properties and the Mössbauer effect for FeRh@FeO composite nanoparticles at different temperatures. An analysis of the results allows us to conclude that superparamagnetic relaxations dominate the formation of the magnetic structure of the nanoparticles. For particle sizes near 10 nm, the antiferromagnetic state is possible near helium temperatures. Further heating contributes to the formation of superparamagnetic behaviour. • Magnetic phase transitions in FeRh nanoparticles have been revealed. • The role of magnetization relaxation in the formation of magnetic ordering is demonstrated. • The electronic structure near iron atoms is characterized. • The effect of iron oxide on the surface of FeRh particles on the magnetic properties has been studied. [ABSTRACT FROM AUTHOR]

Nickel and its alloys are widely used for the synthesis of carbon nanofibers via catalytic chemical vapor deposition of various hydrocarbons. In the present research, a series of Ni-Sn alloys with tin loading varied in a range from 0.1 to 25.0 at% were prepared and characterized. Alloying of nickel with a small amount of tin was found to accelerate significantly the catalytic process of ethylene decomposition accompanied by carbon deposition. For the NiSn(0.25) sample, the carbon yield reaches 195 g/g cat after 30 min at 550 °C. At the highest Sn loading (25.0 at%), the process is completely suppressed. A new mechanism explaining the observed interaction of ethylene with Ni-Sn alloys was proposed. Single-atom Sn species are responsible for the increased catalytic activity. A single-atom Ni-Sn alloy is considered an efficient catalyst with enhanced stability for the production of carbon nanofibers. [Display omitted] • A series of Ni-Sn alloys containing from 0.1 to 25.0 at% Sn were prepared and studied. • Catalytic chemical vapor deposition of ethylene was used to synthesize carbon nanofibers. • Single-atom Sn accelerates the CCVD process by facilitating the dehydrogenation stage. • At the highest Sn content (25.0 wt%), the CCVD process is completely suppressed. • A new mechanism for the interaction of ethylene with Ni-Sn alloys was proposed. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ni-Sn catalysts with superior selectivity were created for LOHCs hydrogen evolution; • They are based on high-loaded nickel catalyst formulation; • Optimal catalyst has atomic ratio of Ni:Sn of 5:1 and is reduced at 500 °C; • Dehydrogenation selectivity reached over 99 % at MCH conversion of 92 %; • High selectivity of the Ni-Sn catalysts is due to formation of NiSn solid solutions. High-loaded nickel catalysts (HLNCs) modified with Sn were synthesized and tested in dehydrogenation of methylcyclohexane (MCH) as a liquid organic hydrogen carrier. The catalyst composition and its reduction temperature were optimized that enabled to achieve the dehydrogenation selectivity of 99.0 % at a MCH conversion of 92 % and WHSV of 6.0 h−1, while the 99.9 % selectivity was reached at the conversion of 60.4 %, and WHSV of 18.5 h−1. Further, stability of the high selectivity of Sn-modified HLNCs was demonstrated in the long-run (100 h) catalyst test. The genesis of the HLNCs during their modification with Sn and reductive activation in hydrogen was studied. It was shown that the activation at temperatures above 450 °C resulted in a uniform distribution of Sn with the predominant formation of solid NiSn solutions having a crystal lattice of metallic nickel. The formation of the solid solutions provided a decrease in the adsorptive properties relating to the reaction product, toluene, which, in turn, led to an increase in the selectivity of MCH dehydrogenation. [ABSTRACT FROM AUTHOR]

A new approach to hydrothermally synthesize nanocrystalline titanium dioxide with a rutile structure and spherulite-like morphology from titanyl citrate is described herein. It was found that titanium dioxide formed as a result of titanyl citrate thermolysis with the following products: rutile nanocrystals, itaconic acid, and carbon dioxide. Rutile nanocrystals were rod-shaped and oriented in the (101) crystallographic direction. The position of the rutile nanocrystals in the spherulites and pores between the nanocrystals lead to high electrocatalytic activity for the oxygen evolution reaction in alkaline aqueous solutions. The process is characterized by a Tafel slope of 49 mV/dec. Image 1 [ABSTRACT FROM AUTHOR]

Zeolite materials (SAPO-11 or ZSM-5) were used to prepare modified Al 2 O 3 supports by mixing with Al oxide hydroxide, peptization with HNO 3 and subsequent extrusion. The obtained Al 2 O 3 -SAPO-11 and Al 2 O 3 -ZSM-5 (with 30 wt% zeolite content) were impregnated by solutions containing Ni and P precursors: phosphate (A), phosphite (I), and hypophosphite (H). Ni-phosphide catalysts were prepared by temperature-programmed reduction in hydrogen flow and characterized by ICP-AES chemical analysis, low-temperature N 2 physisorption, H 2 -TPR, NH 3 -TPD, XRD, 27Al MAS NMR, XPS. The catalysts were tested in methyl palmitate (MP) hydroconversion (HC, i.e. hydrodeoxygenation (HDO) + hydroisomerization/hydrocracking). 100% MP conversion was achieved over all catalysts (flow reactor at 340 °C, 2.0 MPa, 5.3 h−1). For Ni 2 P/Al 2 O 3 -SAPO-11 catalysts the overall yield of iso-alkanes (iso-C 15 and iso-C 16) increased in the following order of precursors: A < I < H. The highest yield of iso-alkanes was 21% over Ni 2 P/Al 2 O 3 -SAPO-11 H catalyst. Ni 2 P/Al 2 O 3 -ZSM-5 samples possessed high cracking activity. Alkanes from MP HDO as well as the solvent (n-dodecane) were almost completely transformed to C 6 –C 9 alkanes at 340 °C. Decreasing temperature (290, 270 °C) did not result in significant yield of iso-alkanes over Ni 2 P/Al 2 O 3 -ZSM-5 catalysts. [Display omitted] • Ni 2 P/Al 2 O 3 -SAPO-11 and Ni 2 P/Al 2 O 3 -ZSM-5 were prepared from different precursors. • Reduction processes start at different temperatures for different precursors. • Phosphite and hypophosphite precursors give smaller particles. • SAPO-11-containing catalysts produce n- and iso-alkanes (at 340 °C). • ZSM-5 containing catalysts showed high cracking activity at the same conditions. [ABSTRACT FROM AUTHOR]

Parahydrogen-induced polarization (PHIP) was successfully utilized to demonstrate the strong metal-support interaction (SMSI) effect for palladium supported on titania catalysts. Heterogeneous hydrogenation of 1,3-butadiene over Pd/TiO2 catalysts led to the formation of 1- and 2-butenes and butane, and hyperpolarized products were obtained if parahydrogen was used in the reaction. However, if the catalysts were reduced in H2 flow at 500 °C before the hydrogenation reaction, the observed polarization levels were significantly lower or even zero, which was indicative of the suppression of the pairwise addition of hydrogen route. This observation indicated the possibility to detect the SMSI effect by the PHIP technique. Moreover, by using X-ray photoelectron spectroscopy it was shown that Pd is partially present as Pd δ+ after reduction under a hydrogen atmosphere at 500 °C. These results were confirmed by transmission electron microscopy, which revealed the formation of Pd δ+ and the dissolution of Pd in the titania lattice. [ABSTRACT FROM AUTHOR]

In this paper, the influence of surface modification on the characteristics and properties of AlN thin films on Si and glass-ceramics substrates is investigated. The surface modification was made at various parameters of argon cluster ions. By using XRD and Raman spectroscopy, it was shown that the obtained AlN films have a hexagonal structure with a characteristic direction of texturing along the c axis and slight deviations from it. A comparison of the AlN surface morphology obtained by atomic force microscopy before and after cluster processing was demonstrated. This demonstrated that the cluster ions with low energy per atom (E/N = 10 eV/atom) have a high efficiency of surface smoothing. A decrease in the intensity of the Raman peaks and an increase in their full-width after bombardment with cluster ions were found, which may be caused by a change in the physicochemical state of the surface. The optical properties, the quality of the boundaries, and the distribution map of the thickness of the functional layer of AlN were investigated by the methods of spectral and spatial resolution ellipsometry. By using the cross-sectional SEM, the direction of crystallite texturing was demonstrated. The influence of argon cluster ion bombardment on the stoichiometry of samples was analyzed by EDX spectroscopy. The results obtained demonstrate the efficiency of the cluster ion smoothing of polycrystalline thin films for microelectronics, particularly when creating surface acoustic wave resonators. [ABSTRACT FROM AUTHOR]

We explored the photoreforming of rice and corn starch with simultaneous hydrogen production over a Cd0.7Zn0.3S-based photocatalyst under visible light irradiation. The photocatalyst was characterized by UV–vis diffuse reflectance spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The influence of starch pretreatment conditions, such as hydrolysis temperature and alkaline concentration, on the reaction rate was studied. The maximum rate of H2 evolution was 730 μmol·h−1·g−1, with AQE = 1.8% at 450 nm, in the solution obtained after starch hydrolysis in 5 M NaOH at 70 °C. The composition of the aqueous phase of the suspension before and after the photocatalytic reaction was studied via high-performance liquid chromatography, and such products as glucose and sodium gluconate, acetate, formate, glycolate, and lactate were found after the photocatalytic reaction. [ABSTRACT FROM AUTHOR]

The Front Cover shows that the SMSI (strong metal–support interaction) observed for palladium supported on titania catalysts, along with the formation of a Pdδ+ state during high‐temperature (500 °C) hydrogen treatment, dramatically reduces the pairwise hydrogen addition activity of the Pd/TiO2 catalyst. In their Communication, Kovtunov et al. demonstrate that formation of the Pdδ+ state by encapsulation of Pd metal nanoparticles, confirmed by XPS and TEM techniques, correlates with the decrease in the number of active sites responsible for pairwise hydrogen addition. Utilization of the PHIP (parahydrogen–induced polarization) technique to investigate the SMSI effects, along with TEM and XPS analysis, demonstrated that PHIP effects are more sensitive to the onset of SMSI effects compared with catalytic activity or chemisorption measurements. More details can be found in the Communication by Kovtunov et al. on page 2581 in Issue 17, 2015. (DOI: 10.1002/cctc.201500618). [ABSTRACT FROM AUTHOR]

The front cover artwork for Issue 17/2015 is a collaboration between the International Tomography Center (Russia) and the Boreskov Institute of Catalysis (Russia). The image shows that palladium catalysts supported on titania and reduced in H2 flow at 500 °C exhibit a SMSI (strong metal-support interaction) effect, which dramatically reduces the pairwise hydrogen addition activity. See the Communication itself at . [ABSTRACT FROM AUTHOR]