Catalytic Behaviour of Mesoporous Cobalt-Aluminum Oxides for CO Oxidation

Ordered mesoporous materials are promising catalyst supports due to their uniform pore size distribution, high specific surface area and pore volume, tunable pore sizes, and long-range ordering of the pore packing. The evaporation-induced self-assembly (EISA) process was applied to synthesize mesoporous mixed oxides, which consist of cobalt ions highly dispersed in an alumina matrix. The characterization of the mesoporous mixed cobalt-aluminum oxides with cobalt loadings in the range from 5 to 15 wt% and calcination temperatures of 673, 973, and 1073 K indicates that Co2+ is homogeneously distributed in the mesoporous alumina matrix. As a function of the Co loading, different phases are present comprising poorly crystalline alumina and mixed cobalt aluminum oxides of the spinel type. The mixed cobalt-aluminum oxides were applied as catalysts in CO oxidation and turned out to be highly active.Fil: Bordoloi, Ankur. Indian Institute of Petroleum; IndiaFil: Sanchez, Miguel Dario. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Física del Sur. Universidad Nacional del Sur. Departamento de Física. Instituto de Física del Sur; ArgentinaFil: Noei, Heshmat. Research Group X-Ray Physics and Nanoscience Deutsches Elektronen-Synchrotron; AlemaniaFil: Kaluza, Stefan. Fraunhofer Institute of Environmental, Safety, and Energy Technology; AlemaniaFil: Großmann, Dennis. Ruhr Universität Bochum; AlemaniaFil: Wang, Yuemin. Ruhr Universität Bochum; AlemaniaFil: Grünert, Wolfgang. Ruhr Universität Bochum; AlemaniaFil: Muhler, Martin. Ruhr Universität Bochum; Alemani

New insight into calcium tantalate nanocomposite photocatalysts for overall water splitting and reforming of alcohols and biomass derivatives

The photocatalytic properties of different calcium tantalate nanocomposite photocatalysts with optimized phase composition were studied without the addition of any co-catalysts in the photoreforming of different alcohols including the biomass conversion by-product glycerol, as well as after modification with double-layered NiOx (Ni/NiO) co-catalyst in overall water splitting (OWS). Nanocomposite photocatalyst consisting of cubic ??-CaTa2O6/orthorhombic ??-CaTa2O6 coexisting phases always possesses the highest photocatalytic performance. For overall water splitting, a loading of 0.5 wt. % NiOx exhibits the best activities with stable stoichiometric H2 and O2 evolution rates.close0

Probing Oxide Reduction and Phase Transformations at the Au-TiO2 Interface by Vibrational Spectroscopy

By a combination of FT-NIR Raman spectroscopy, infrared spectroscopy of CO adsorption under ultrahigh vacuum conditions (UHV-IR) and Raman spectroscopy in the line scanning mode the formation of a reduced titania phase in a commercial Au/TiO2 catalyst and in freshly prepared Au/anatase catalysts was detected. The reduced phase, formed at the Au-TiO2 interface, can serve as nucleation point for the formation of stoichiometric rutile. TinO2n−1 Magnéli phases, structurally resembling the rutile phase, might be involved in this process. The formation of the reduced phase and the rutilization process is clearly linked to the presence of gold nanoparticles and it does not proceed under similar conditions with the pure titania sample. Phase transformations might be both thermally or light induced, however, the colloidal deposition synthesis of the Au/TiO2 catalysts is clearly ruled out as cause for the formation of the reduced phase

Spinel-structured ZnCr2O4 with excess Zn is the active ZnO/Cr2O3 catalyst for high-temperature methanol synthesis

A series of ZnO/Cr2O3 catalysts with different Zn:Cr ratios was prepared by coprecipitation at a constant pH of 7 and applied in methanol synthesis at 260–300 °C and 60 bar. The X-ray diffraction (XRD) results showed that the calcined catalysts with ratios from 65:35 to 55:45 consist of ZnCr2O4 spinel with a low degree of crystallinity. For catalysts with Zn:Cr ratios smaller than 1, the formation of chromates was observed in agreement with temperature-programmed reduction results. Raman and XRD results did not provide evidence for the presence of segregated ZnO, indicating the existence of Zn-rich nonstoichiometric Zn–Cr spinel in the calcined catalyst. The catalyst with Zn:Cr = 65:35 exhibits the best performance in methanol synthesis. The Zn:Cr ratio of this catalyst corresponds to that of the Zn4Cr2(OH)12CO3 precursor with hydrotalcite-like structure obtained by coprecipitation, which is converted during calcination into a nonstoichiometric Zn–Cr spinel with an optimum amount of oxygen vacancies resulting in high activity in methanol synthesis. Density functional theory calculations are used to examine the formation of oxygen vacancies and to measure the reducibility of the methanol synthesis catalysts. Doping Cr into bulk and the (10–10) surface of ZnO does not enhance the reducibility of ZnO, confirming that Cr:ZnO cannot be the active phase. The (100) surface of the ZnCr2O4 spinel has a favorable oxygen vacancy formation energy of 1.58 eV. Doping this surface with excess Zn charge-balanced by oxygen vacancies to give a 60% Zn content yields a catalyst composed of an amorphous ZnO layer supported on the spinel with high reducibility, confirming this as the active phase for the methanol synthesis catalyst

Demonstrating the steady performance of iron oxide composites over 2000 cycles at fast charge-rates for Li-ion batteries

The feasibility of using iron oxides as negative electrode materials for safe high-power Li-ion batteries is demonstrated by the carbon-coated FeO/CNT composite synthesized by controlled pyrolysis of ferrocene, which delivered a specific capacity retention of 84% (445 mA h g) after 2000 cycles at 2000 mA g (4C)

Історико-правові аспекти інформаційного протиборства в умовах воєнного стану (1941 – 1942 рр.)

Щодо впливу на людину засобів інформаційно-пропагандистської зброї.О влиянии на человека средств информационно-пропагандистского оружия.On influence of the methods of informative propagandistic weapon on the human

Cobalt boride modified with N-doped carbon nanotubes as a high-performance bifunctional oxygen electrocatalyst

The development of reversible oxygen electrodes, able to drive both the oxygen evolution reaction (OER) and the oxygen reduction reaction (ORR), is still a great challenge. We describe a very efficient and stable bifunctional electrocatalytic system for reversible oxygen electrodes obtained by direct CVD growth of nitrogen-doped carbon nanotubes (NCNTs) on the surface of cobalt boride (CoB) nanoparticles. A detailed investigation of the crystalline structure and elemental distribution of CoB before and after NCNT growth reveals that the NCNTs grow on small CoB nanoparticles formed in the CVD process. The resultant CoB/NCNT system exhibited outstanding activity in catalyzing both the OER and the ORR in 0.1 M KOH with an overvoltage difference of only 0.73 V between the ORR at -1 mA cm⁻² and the OER at +10 mA cm⁻². The proposed CoB/NCNT catalyst showed stable performance during 50 h of OER stability assessment in 0.1 M KOH. Moreover, CoB/NCNT spray-coated on a gas diffusion layer as an air-breathing electrode proved its high durability during 170 galvanostatic charge-discharge (OER/ORR) test cycles (around 30 h) at ±10 mA cm⁻² in 6 M KOH, making it an excellent bifunctional catalyst for potential Zn-air battery application