Bimetallic CuPd nanoparticles supported on ZnO or graphene for CO and CO conversion to methane and methanol.

Carbon dioxide (CO) and carbon monoxide (CO) hydrogenation to methane (CH) or methanol (MeOH) is a promising pathway to reduce CO emissions and to mitigate dependence on rapidly depleting fossil fuels. Along these lines, a series of catalysts comprising copper (Cu) or palladium (Pd) nanoparticles (NPs) supported on zinc oxide (ZnO) as well as bimetallic CuPd NPs supported on ZnO or graphene were synthesized various methodologies. The prepared catalysts underwent comprehensive characterization high-resolution transmission electron microscopy (HRTEM), energy-dispersive X-ray spectroscopy (EDX) mapping, electron energy loss spectroscopy (EELS), X-ray diffraction (XRD), hydrogen temperature-programmed reduction and desorption (H-TPR and H-TPD), and deuterium temperature-programmed desorption (DO-TPD).

Electro-tuned catalysts: voltage-controlled activity selection of bimetallic exsolution particles.

In this work, we show how the activity states of bimetallic Ni-Fe catalysts exsolved from NdCaFeNiO (NCFNi) can be influenced electrochemically. The NCFNi parent oxide was employed in the form of thin film mixed conducting model electrodes, which were operated in a humid hydrogen atmosphere. By precisely controlling the oxygen chemical potential in the parent oxide electrode applying an electrochemical polarisation, we managed to selectively exsolve Ni nanoparticles from the perovskite lattice and study their catalytic activity switching characteristics.

Discrimination of coherent and incoherent cathodoluminescence using temporal photon correlations.

We present a method to separate coherent and incoherent contributions of cathodoluminescence (CL) by using a time-resolved coincidence detection scheme. For a proof-of-concept experiment, we generate CL by irradiating an optical multimode fiber with relativistic electrons in a transmission electron microscope. A temporal analysis of the CL reveals a large peak in coincidence counts for small time delays, also known as photon bunching.

True Nature of the Transition-Metal Carbide/Liquid Interface Determines Its Reactivity.

Compound materials, such as transition-metal (TM) carbides, are anticipated to be effective electrocatalysts for the carbon dioxide reduction reaction (CORR) to useful chemicals. This expectation is nurtured by density functional theory (DFT) predictions of a break of key adsorption energy scaling relations that limit CORR at parent TMs. Here, we evaluate these prospects for hexagonal MoC in aqueous electrolytes in a multimethod experiment and theory approach.

Method for the production of pure and C-doped nanoboron powders tailored for superconductive applications.

The present paper describes the improvement of the performances of boron powder obtained applying the freeze-drying process (FDP) for the nanostructuration and doping of BO, which is here used as boron precursor. After the nanostructuration process, BO is reduced to elemental nanoboron (nB) through magnesiothermic reaction with Mg. For this work, the usefulness of the process was tested focusing on the carbon-doping (C-doping), using C, inulin and haemoglobin as C sources.

Elastic propagation of fast electron vortices through amorphous materials.

This work studies the elastic scattering behavior of electron vortices when propagating through amorphous samples. A formulation of the multislice approach in cylindrical coordinates is used to theoretically investigate the redistribution of intensity between different angular momentum components due to scattering. To corroborate and elaborate on our theoretical results, extensive numerical simulations are performed on three model systems (SiN, FeB, Pt) for a wide variety of experimental parameters to quantify the purity of the vortices, the net angular momentum transfer, and the variability of the results with respect to the random relative position between the electron beam and the scattering atoms.

An ultra-flexible modular high vacuum setup for thin film deposition.

A modular high vacuum chamber dedicated to thin film deposition is presented. We detail the vacuum and gas infrastructure required to operate two highly flexible chambers simultaneously, with a focus on evaporation techniques (thermal and electron beam) and magnetron sputtering, including baking equipment to remove residual water from the chamber. The use of O-ring-sealed flat flanges allows a tool-free assembly process, in turn enabling rapid changes of the whole setup.

Valence EELS below the limit of inelastic delocalization using conical dark field EFTEM or Bessel beams.

In this experimental work we present novel methods to increase the spatial resolution of valence electron energy loss spectrometry (VEELS) investigations below the limit given by the inelastic delocalization. For this purpose we analyse a layer stack consisting of silicon/silicon-oxide/silicon-nitride/silicon-oxide/silicon (SONOS) with varying layer thickness down to the 2nm level. Using a combination of a conical illumination and energy filtered transmission electron microscopy we are able to identify the layers by using low energy losses.

High-Temperature Carbon Deposition on Oxide Surfaces by CO Disproportionation.

Carbon deposition due to the inverse Boudouard reaction (2CO → CO + C) has been studied on yttria-stabilized zirconia (YSZ), YO, and ZrO in comparison to CH by a variety of different chemical, structural, and spectroscopic characterization techniques, including electrochemical impedance spectroscopy (EIS), Fourier-transform infrared (FT-IR) spectroscopy and imaging, Raman spectroscopy, and electron microscopy. Consentaneously, all experimental methods prove the formation of a more or less conducting carbon layer (depending on the used oxide) of disordered nanocrystalline graphite covering the individual grains of the respective pure oxides after treatment in flowing CO at temperatures above ∼1023 K. All measurements show that during carbon deposition, a more or less substantial surface reduction of the oxides takes place.