Noncollinear Magnetic Structures in the Chiral Antiperovskite β-FeSeO.

We present the magnetic properties of the chiral, polar, and possibly magnetoelectric antiperovskite β-FeSeO as derived from magnetization and specific-heat measurements as well as from powder neutron diffraction and Mössbauer experiments. Our macroscopic data unambiguously reveal two magnetic phase transitions at ≈ 103 K and ≈ 78 K, while Rietveld analysis of neutron powder diffraction data reveals a noncollinear antiferromagnetic structure featuring magnetic moments in the - plane of the trigonal structure and a ferromagnetic moment along . The latter is allowed by symmetry between and , weakly visible in the magnetization data yet unresolvable microscopically.

Controlling nanocluster growth through nanoconfinement: the effect of the number and nature of metal-organic framework functionalities.

Controlled nanocluster growth nanoconfinement is an attractive approach as it allows for geometry control and potential surface-chemistry modification simultaneously. However, it is still not a straight-forward method and much of its success depends on the nature and possibly concentration of functionalities on the cavity walls that surround the clusters. To independently probe the effect of the nature and number of functional groups on the controlled Pd nanocluster growth within the pores of the metal-organic frameworks, Pd-laden UiO-66 analogues with mono- and bi-functionalised linkers of amino and methyl groups were successfully prepared and studied in a combined experimental-computational approach.

Restructuring dynamics of surface species in bimetallic nanoparticles probed by modulation excitation spectroscopy.

Restructuring of metal components on bimetallic nanoparticle surfaces in response to the changes in reactive environment is a ubiquitous phenomenon whose potential for the design of tunable catalysts is underexplored. The main challenge is the lack of knowledge of the structure, composition, and evolution of species on the nanoparticle surfaces during reaction. We apply a modulation excitation approach to the X-ray absorption spectroscopy of the 30 atomic % Pd in Au supported nanocatalysts via the gas (H and O) concentration modulation.

PEPICO analysis of catalytic reactor effluents towards quantitative isomer discrimination: DME conversion over a ZSM-5 zeolite.

The methanol-to-hydrocarbons (MTH) process involves the conversion of methanol, a C1 feedstock that can be produced from green sources, into hydrocarbons using shape-selective microporous acidic catalysts - zeolite and zeotypes. This reaction yields a complex mixture of species, some of which are highly reactive and/or present in several isomeric forms, posing significant challenges for effluent analysis. Conventional gas-phase chromatography (GC) is typically employed for the analysis of reaction products in laboratory flow reactors.

Development of a new class of stable and adaptable free-standing fibre mats with high room-temperature hydroxide-ion conductivity.

For alkaline anion-exchange membrane electrolysers and fuel cells to become a technological reality, hydroxide-ion (OH) conducting membranes that are flexible, robust, affording high OH conductivity, and synthesised in a low-cost and scalable way must be developed. In this paper, we engineer a stable, self-supporting, and flexible fibre mat using a low-cost ZIF-8 metal-organic framework composited with ionic liquid tetrabutylammonium hydroxide and widely used polyacrylonitrile as polymeric backbone. We obtain mats with a high intrinsic OH conductivity for a metal-organic framework-based material already at room temperature, without added ion-conductor polymers.

Synthesis and Properties of BaTeS (M = Fe, Mn, Zn) and the Disordered Structural Analog BaGeTeS.

A series of tertiary sulfide-tellurides, BaTeS (M = Fe, Mn, Zn, Ge), has been synthesized by solid-state synthesis. The compounds assume an orthorhombic crystal structure, described by the (No. 63) space group, and are structural analogs of the BaSO (M = Co, Zn) phases.

Zn Redistribution and Volatility in ZnZrO Catalysts for CO Hydrogenation.

ZnO-ZrO mixed oxide (ZnZrO) catalysts are widely studied as selective catalysts for CO hydrogenation into methanol at high-temperature conditions (300-350 °C) that are preferred for the subsequent zeolite-catalyzed conversion of methanol into hydrocarbons in a tandem process. Zn, a key ingredient of these mixed oxide catalysts, is known to volatilize from ZnO under high-temperature conditions, but little is known about Zn mobility and volatility in mixed oxides. Here, an array of and characterization techniques (scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDX), transmission electron microscopy (TEM), powder X-ray diffraction (PXRD), X-ray absorption spectroscopy (XAS), X-ray photoelectron spectroscopy (XPS), Infrared (IR)) was used to reveal that Zn species are mobile between the solid solution phase with ZrO and segregated and/or embedded ZnO clusters.

Understanding C-H activation in light alkanes over Cu-MOR zeolites by coupling advanced spectroscopy and temperature-programmed reduction experiments.

The direct activation of methane to methanol (MTM) proceeds through a chemical-looping process over Cu-oxo sites in zeolites. Herein, we extend the overall understanding of oxidation reactions over metal-oxo sites and C-H activation reactions by pinpointing the evolution of Cu species during reduction. To do so, a set of temperature-programmed reduction experiments were performed with CH, CH and CO.

X-ray and Neutron Diffraction Studies of SrTeFeOCl, an Oxide Chloride with Rare Anion Ordering.

The oxychloride SrTeFeOCl is obtained by high-temperature solid-state synthesis under inert conditions in closed reaction vessels. The compound crystallizes in a novel monoclinic crystal structure that is described in the space group 12/1 (No. 14).

Synthesis and Properties of BaFeTeS, with an Fe Dimer in a Magnetic Singlet State.

A new quaternary sulfide telluride, BaFeTeS, was synthesized by a solid-state reaction, and its crystal structure is novel. X-ray diffraction data on powder and single crystals reveal an orthorhombic lattice with = 9.7543(3) Å, = 18.

Cu-loaded zeolites enable the selective activation of ethane to ethylene at low temperatures and pressure.

Cu-zeolites are found to activate the C-H bond of ethane already at 150 °C in a cyclic protocol and form ethylene with a high selectivity. Both the zeolite topology and Cu content are found to impact the ethylene yield. Ethylene adsorption studies with FT-IR, demonstrate that oligomerization of ethylene occurs over protonic zeolites, while this reaction does not occur over Cu-zeolites.

Energetics of formation and stability in high pressure steam of barium lanthanide cobaltite double perovskites.

This study concerns energetics of formation and the stability in high water partial pressure of BaLnCoO, (Ln = La, Pr, Nd, and Gd) (BLnC) and BaGdLaCoO, where = 0.2, 0.5, and 0.

Aligning time-resolved kinetics (TAP) and surface spectroscopy (AP-XPS) for a more comprehensive understanding of ALD-derived 2D and 3D model catalysts.

The spectro-kinetic characterization of complex catalytic materials, relating the observed reaction kinetics to spectroscopic descriptors of the catalyst state, presents a fundamental challenge with a potentially significant impact on various chemical technologies. We propose to reconcile the kinetic characteristics available from temporal analysis of products (TAP) pulse-response kinetic experiments with the spectroscopic data available from ambient pressure X-ray photoelectron spectroscopy (AP-XPS), using atomic layer deposition (ALD) to synthesize multicomponent model surfaces on 2D and 3D supports. The accumulated surface exposure to a key reactant (total number of collisions) is used as a common scale within which the results from the two techniques can be rigorously compared for microscopically-equivalent surfaces.

Quantifiable models for surface protonic conductivity in porous oxides - case of monoclinic ZrO.

The surface protonic conductivity of porous monoclinic ZrO sintered at temperatures in the range 700-1100 °C yielding relative densities of around 60% and grain sizes of approximately 160 nm has been studied using impedance spectroscopy as a function of temperature well below the sintering temperature in wet atmospheres ( = 0.03 bar). The sum of two high-frequency impedance responses is argued to represent surface conductance according to a new model of impedance over curved surfaces.

Synchronizing gas injections and time-resolved data acquisition for perturbation-enhanced APXPS experiments.

An experimental approach is described in which well-defined perturbations of the gas feed into an Ambient Pressure X-ray Photoelectron Spectroscopy (APXPS) cell are fully synchronized with the time-resolved x-ray photoelectron spectroscopy data acquisition. These experiments unlock new possibilities for investigating the properties of materials and chemical reactions mediated by their surfaces, such as those in heterogeneous catalysis, surface science, and coating/deposition applications. Implementation of this approach, which is termed perturbation-enhanced APXPS, at the SPECIES beamline of MAX IV Laboratory is discussed along with several experimental examples including individual pulses of N gas over a Au foil, a multi-pulse titration of oxygen vacancies in a pre-reduced TiO single crystal with O gas, and a sequence of alternating precursor pulses for atomic layer deposition of TiO on a silicon wafer substrate.

Gold(I) N-heterocyclic carbene precursors for focused electron beam-induced deposition.

Seven gold(I) N-heterocyclic carbene (NHC) complexes were synthesized, characterized, and identified as suitable precursors for focused electron beam-induced deposition (FEBID). Several variations on the core Au(NHC)X moiety were introduced, that is, variations of the NHC ring (imidazole or triazole), of the alkyl N-substituents (Me, Et, or iPr), and of the ancillary ligand X (Cl, Br, I, or CF). The seven complexes were tested as FEBID precursors in an on-substrate custom setup.

Near-Broken-Gap Alignment between FeWO and FeWO for Ohmic Direct p-n Junction Thermoelectrics.

We report a near-broken-gap alignment between p-type FeWO and n-type FeWO, a model pair for the realization of Ohmic direct junction thermoelectrics. Both undoped materials have a large Seebeck coefficient and high electrical conductivity at elevated temperatures, due to inherent electronic defects. A band-alignment diagram is proposed based on X-ray photoelectron and ultraviolet-visible light reflectance spectroscopy.

A soft chemistry approach to the synthesis of single crystalline and highly pure (NH)CoF for optical and magnetic investigations.

A new ionothermal synthesis utilizing 1-alkyl-pyridinium hexafluorophosphates [CPy][PF] (x = 2, 4, 6) led to the formation of highly crystalline single-phase ammonium cobalt trifluoride, (NH)CoF. Although ammonium transition-metal fluorides have been extensively studied with respect to their structural and magnetic properties, multiple aspects remain unclear. For that reason, the obtained (NH)CoF has been investigated over a broad temperature range by means of single-crystal and powder x-ray diffraction as well as magnetization and specific heat measurements.

Phase and Orientation Control of NiTiO Thin Films.

Subtle changes in the atomic arrangement of NiTiO in the ilmenite structure affects its symmetry and properties. At high temperatures, the cations are randomly distributed throughout the structure, resulting in the corundum structure with -3 symmetry. Upon cooling, the cations order in alternating layers along the crystallographic axis, resulting in the ilmenite structure with -3 symmetry.

Synthesis, Crystal Structure, and Optical Characterization of the Sulfide Chloride Oxide CsBaVSClO with a Near-Infrared Fluorescence.

When CsCl, BaS, BaO, V, and S are reacted in a solid-state reaction under inert conditions, pure powders and single crystals of senary CsBaVSClO can be obtained. Its unique crystal structure has the symmetry 3̅ (no. 148) and unit cell parameters = 9.

Oligomerization of Light Olefins Catalyzed by Brønsted-Acidic Metal-Organic Framework-808.

Sulfated metal-organic framework-808 (S-MOF-808) exhibits strong Brønsted-acidic character which makes it a potential candidate for the heterogeneous acid catalysis. Here, we report the isomerization and oligomerization reactions of light olefins (C3-C6) over S-MOF-808 at relatively low temperatures and ambient pressure. Different products (dimers, isomers, and heavier oligomers) were obtained for different olefins, and effective C-C coupling was observed between isobutene and isopentene.

Mixed proton and electron conducting double perovskite anodes for stable and efficient tubular proton ceramic electrolysers.

Hydrogen production from water electrolysis is a key enabling energy storage technology for the large-scale deployment of intermittent renewable energy sources. Proton ceramic electrolysers (PCEs) can produce dry pressurized hydrogen directly from steam, avoiding major parts of cost-driving downstream separation and compression. However, the development of PCEs has suffered from limited electrical efficiency due to electronic leakage and poor electrode kinetics.

Formation and Functioning of Bimetallic Nanocatalysts: The Power of X-ray Probes.

Bimetallic nanocatalysts are key enablers of current chemical technologies, including car exhaust converters and fuel cells, and play a crucial role in industry to promote a wide range of chemical reactions. However, owing to significant characterization challenges, insights in the dynamic phenomena that shape and change the working state of the catalyst await further refinement. Herein, we discuss the atomic-scale processes leading to mono- and bimetallic nanoparticle formation and highlight the dynamics and kinetics of lifetime changes in bimetallic catalysts with showcase examples for Pt-based systems.

Biocompatible organic-inorganic hybrid materials based on nucleobases and titanium developed by molecular layer deposition.

We have constructed thin films of organic-inorganic hybrid character by combining titanium tetra-isopropoxide (TTIP) and the nucleobases thymine, uracil or adenine using the molecular layer deposition (MLD) approach. Such materials have potential as bioactive coatings, and the bioactivity of these films is described in our recent work [Momtazi, L.; Dartt, D.