Butenes and butadiene, which are useful intermediates for the synthesis of polymers other compounds, synthesized traditionally by oxidative dehydrogenation (ODH) n-butane over complex metal oxides. Such catalysts require high O2/butane ratios to maintain activity, leads unwanted product oxidation. We show that carbon nanotubes with modified surface functionality efficiently catalyze butenes, especially butadiene. For low ratios, a selectivity alkenes was achieved periods as long 100 hours....

The surface chemical properties and the electronic of vapor grown carbon nanofibers (VGCNFs) have been modified by treatment oxidized CNFs with NH(3). effect temperature on types nitrogen functionalities introduced was evaluated synchrotron based X-ray photoelectron spectroscopy (XPS), while impact preparation methods acid-base investigated potentiometric titration, microcalorimetry, zeta potential measurements. N-functionalization measured THz-Time Domain spectroscopy. samples...

Boron makes it selective: Carbon nanotubes (CNTs) modified by boron oxide catalyze the oxidative dehydrogenation of propane to propene with remarkable selectivity. Nanocarbon can be an attractive alternative conventional metal oxides, as enables a feasible investigation reaction mechanism and provides sustainable technology for alkane conversion.

Hard core: A hybrid catalyst system for dehydrogenation of ethylbenzene comprises nanoparticles consisting nanodiamond cores and highly curved, defective graphene shells (see picture). The exhibits high catalytic activity selectivity over a long period time. In contrast to industrial K-promoted Fe catalysts, steam decoking the is not required.

Low-temperature (∼450 °C), scalable chemical vapor deposition of predominantly monolayer (74%) graphene films with an average D/G peak ratio 0.24 and domain sizes in excess 220 μm2 is demonstrated via the design alloy catalysts. The admixture Au to polycrystalline Ni allows a controlled decrease nucleation density, highlighting role step edges. In situ, time-, depth-resolved X-ray photoelectron spectroscopy diffraction reveal subsurface C species allow coherent model for formation be devised.

Complementary in situ X-ray photoelectron spectroscopy (XPS), diffractometry, and environmental scanning electron microscopy are used to fingerprint the entire graphene chemical vapor deposition process on technologically important polycrystalline Cu catalysts address current lack of understanding underlying fundamental growth mechanisms catalyst interactions. Graphene forms directly metallic during high-temperature hydrocarbon exposure, whereby an upshift binding energies corresponding C1s...

Abstract X‐ray photoelectron spectroscopy (XPS) is a widely used technique for characterizing the chemical and electronic properties of highly ordered carbon nanostructures, such as nanotubes graphene. However, analysis XPS data—in particular C 1s region—can be complex, impeding straightforward evaluation data. In this work, an overview extrinsic intrinsic effects that influence spectra—for example, photon broadening or carbon–catalyst interaction—of various graphitic samples presented....

Using a combination of complementary in situ X-ray photoelectron spectroscopy and diffraction, we study the fundamental mechanisms underlying chemical vapor deposition (CVD) hexagonal boron nitride (h-BN) on polycrystalline Cu. The nucleation growth h-BN layers is found to occur isothermally, i.e., at constant elevated temperature, Cu surface during exposure borazine. A lattice expansion borazine B precipitation from upon cooling highlight that incorporated into bulk, not just...

Controlling the charge transfer between a semiconducting catalyst carrier and supported transition metal active phase represents an elite strategy for fine turning electronic structure of catalytic centers, hence their activity selectivity. These phenomena have been theoretically experimentally elucidated oxide supports but remain poorly understood carbons due to complex nanoscale structure. Here, we combine advanced spectroscopy microscopy on model Pd/C samples decouple surface chemistry...

We study catalyst support interactions during chemical vapor deposition of carbon nanotubes by in situ X-ray photoelectron spectroscopy over a wide range pressures. observe Fe 2+ and 3+ interface states for metallic on Al2O3 the absence measurable Al reduction. This interaction is much stronger than that SiO2, it restricts surface mobility. The resulting narrower particle size distribution leads to higher nanotube nucleation density vertical alignment due proximity effects. record growth...

We report that nanoparticulate zirconia (ZrO(2)) catalyzes both growth of single-wall and multiwall carbon nanotubes (CNTs) by thermal chemical vapor deposition (CVD) graphitization solid amorphous carbon. observe silica-, silicon nitride-, alumina-supported on nucleates single- upon exposure to hydrocarbons at moderate temperatures (750 degrees C). High-pressure, time-resolved X-ray photoelectron spectroscopy (XPS) these substrates during nanotube nucleation shows the catalyst neither...

We study catalyst−support and catalyst−carbon interactions during the chemical vapor deposition of single-walled carbon nanotubes by combining environmental transmission microscopy in situ, time-resolved X-ray photoelectron spectroscopy. present direct evidence what constitutes catalyst functionality comparing behavior Ni, Fe, Pd, Au model films on SiO2 preannealing O2 NH3 C2H2 decomposition. The metal surface supplies sites to dissociate hydrocarbon precursor then guides formation a lattice...

The key atomistic mechanisms of graphene formation on Ni for technologically relevant hydrocarbon exposures below 600 °C are directly revealed via complementary in situ scanning tunneling microscopy and X-ray photoelectron spectroscopy. For clean Ni(111) 500 °C, two different surface carbide (Ni2C) conversion dominant which both yield epitaxial graphene, whereas above predominantly grows replacement leading to embedded and/or rotated domains. Upon cooling, additional carbon structures form...

The oxygen exchange activity of mixed conducting oxide surfaces has been widely investigated, but a detailed understanding the corresponding reaction mechanisms and rate-limiting steps is largely still missing. Combined in situ investigation electrochemically polarized model electrode under realistic temperature pressure conditions by near-ambient (NAP) XPS impedance spectroscopy enables very surface-sensitive chemical analysis may detect species that are involved step. In present study,...

More than skin deep: In spite of their identical 1:1 surface composition, the geometric and electronic structures a multilayer monolayer PdZn alloy are different, as catalytic selectivities. The CO2 selective features ensembles exhibiting "Zn-up/Pd-down" corrugation (see picture). These act "bifunctional" active sites both for water activation conversion methanol into CO2. On CO not is produced.

Any substantial move of energy sources from fossil fuels to renewable resources requires large scale storage excess energy, for example, via power fuel processes. In this respect electrochemical reduction CO2 may become very important, since it offers a method sustainable CO production, which is crucial prerequisite synthesis fuels. Carbon dioxide in solid oxide electrolysis cells (SOECs) particularly promising owing the high operating temperature, leads both improved thermodynamics and fast...

The long-term (>18 months) protection of Ni surfaces against oxidation under atmospheric conditions is demonstrated by coverage with single-layer graphene, formed chemical vapor deposition. In situ, depth-resolved X-ray photoelectron spectroscopy various graphene-coated transition metals reveals that a strong graphene–metal interaction key importance in achieving this protection. This prevents the rapid intercalation oxidizing species at interface and thus suppresses substrate surface....

Black matter in catalysis: Graphitic carbon catalyzes the insertion of O atoms into acrolein. Such complex multistep atom rearrangements were believed to be exclusive domain metal (oxide) catalysis. In C-catalyzed process, nucleophilic terminating graphite (0001) surface abstract formyl H and activated aldehyde is oxidized by a mobile epoxide atom. Thus, sp2 acts as bifunctional catalyst. Detailed facts importance specialist readers are published "Supporting Information". documents...

Sneaked in: Carbon atoms from defective supports are incorporated in nickel nanoparticles at relatively low temperatures (for example a Ni(100) surface; Ni brown, C black) The dissolved carbon not only modifies the electronic properties of metal but it also leads to reconstruction nanoparticles. These findings may explain many differences catalytic activity observed when supporting metals on carbon.

Abstract In the search for optimized cathode materials high‐temperature electrolysis, mixed conducting oxides are highly promising candidates. This study deals with fundamentally novel insights into relation between surface chemistry and electrocatalytic activity of lanthanum ferrite based electrolysis cathodes. For this means, near‐ambient‐pressure X‐ray photoelectron spectroscopy (NAP‐XPS) impedance experiments were performed simultaneously on electrochemically polarized La 0.6 Sr 0.4 FeO...

Highly controlled Fe-catalyzed growth of monolayer hexagonal boron nitride (h-BN) films is demonstrated by the dissolution nitrogen into catalyst bulk via NH3 exposure prior to actual step. This “pre-filling” reservoir allows us control and limit uptake B N species during borazine thereby incubation time h-BN kinetics while also limiting contribution uncontrolled precipitation-driven cooling. Using in situ X-ray diffraction photoelectron spectroscopy combined with systematic calibrations, we...

Intercalation of oxygen at the interface graphene grown by chemical vapour deposition and its polycrystalline copper catalyst can have a strong impact on electronic, structural properties both Cu. This affect oxidation resistance metal as well subsequent transfer. Here, we show, using near ambient pressure X-ray photoelectron spectroscopy (NAP-XPS), absorption edge (XANES), energy dispersive (EDX) (environmental) scanning electron microscopy (ESEM) that intercalation de-intercalation are...