johnnyas

• Andersen, Eline Haug; Sannes, Johnny Andreas; Frøen, Emil Herman; Nilsen, Ola & Valldor, Björn Martin (2025). Diamagnetic sulfide Ba3Sc2S6 – With infinite [ScS6/2] chains as structural element. Journal of Solid State Chemistry. ISSN 0022-4596. 342. doi: 10.1016/j.jssc.2024.125105. Fulltekst i vitenarkiv Vis sammendrag

  The sulfide Ba3Sc2S6 was synthesized by the conventional high-temperature solid-state technique in an inert atmosphere, utilizing sealed silica ampules with low internal pressure of Ar gas. The crystal structure was determined by single crystal X-ray diffraction and can be described by a trigonal crystal lattice with rhombohedral symmetry, R 3‾ c (No. 167), with powder diffraction unit cell parameters a = 12.0402(1) Å and c = 13.3893(2) Å. The compound crystallizes with the K4CdCl6-type structure, which has been used to describe homologous sulfides. This crystal structure shares features with the 2H-perovskites but contains infinite 1D chains, Niggli notation [ScS6/2]∞1, consisting of alternating, distorted octahedra and trigonal prisms connected by face-sharing. Ba3Sc2S6 is diamagnetic, as determined from magnetic susceptibility measurements. UV–Vis spectroscopy data suggest a direct bandgap of about 2.88 eV. Further, DFT calculations reveal a band gap of about 1.8 eV and 2.9 eV using the PBE and the HSE06 functional, respectively, of which the latter agrees perfectly with UV–Vis observations.

• Sannes, Johnny Andreas; Chatzitakis, Athanasios; Andersen, Niels Højmark; Nilsen, Ola; Frøen, Emil Herman & Valldor, Björn Martin (2024). Characterization and Solid-State UV-Vis Investigations of Photoelectrocatalytically Active La5Cl7[TeO3]4, a Mixed Anion Compound with Alternating 2D Layers of Oxygen and Chlorine. Inorganic Chemistry. ISSN 0020-1669. 63(40), s. 18632–18641. doi: 10.1021/acs.inorgchem.4c02392. Fulltekst i vitenarkiv Vis sammendrag

  An oxide chloride, La5Cl7[TeO3]4, was synthesized using the conventional high-temperature solid-state synthesis technique in an inert atmosphere. This compound possesses a novel crystal structure that can be described with the triclinic space group P1̅ (No. 2) and unit cell parameters: a = 7.2634(3) Å, b = 8.1241(3) Å, c = 9.1993(3) Å, α = 79.373(1)°, β = 83.599(1)°, and γ = 82.511(1)°. The preference of Te(IV) to coordinate to oxygen and direct its lone pair toward the lower charged chlorine results in 2D layers of both oxygen and chlorine, alternating along the crystallographic b-direction. Homoleptic coordination, solely to oxygen, and heteroleptic coordination to oxygen and chlorine are observed for lanthanum, forming layers connected through edge-sharing polyhedra. In the crystal structure, two distinct tellurium positions are observed, with three close Te–O distances, emphasizing an active lone pair. The compound has been investigated by solid-state UV–vis measurements, and a band gap of 3.44 eV has been determined by DFT calculations. Detailed photoelectrochemical measurements clearly indicate that the title compound is photoelectrocatalytically active, showing an n-type behavior. Raman spectroscopy confirms that complex tellurite ions are present in the crystal structure; several observed bands can be assigned to Te–O stretching, reflecting the relatively low crystallographic symmetry of the title compound.

• Sannes, Johnny Andreas & Valldor, Björn Martin (2023). Sr<inf>2</inf>Te<inf>4</inf>V<inf>2</inf>O<inf>13</inf>Cl<inf>2</inf>, a Layered Structure Forming a Canted Antiferromagnetic Ground State. Chemistry of Materials. ISSN 0897-4756. 35(5), s. 2355–2362. doi: 10.1021/acs.chemmater.3c02961. Fulltekst i vitenarkiv
• Sannes, Johnny Andreas; Gonano, Bruno; Fjellvåg, Øystein Slagtern; Kumar, Susmit; Nilsen, Ola & Valldor, Björn Martin (2023). X-ray and Neutron Diffraction Studies of SrTe<inf>2</inf>FeO<inf>6</inf>Cl, an Oxide Chloride with Rare Anion Ordering. Inorganic Chemistry. ISSN 0020-1669. 62(32), s. 13081–13088. doi: 10.1021/acs.inorgchem.3c01951. Fulltekst i vitenarkiv Vis sammendrag

  The oxychloride SrTe2FeO6Cl 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 P121/n1 (No. 14). The unit cell parameters, a = 10.2604(1) Å, b = 5.34556(5) Å, c = 26.6851(3) Å, and β = 93.6853(4)°, and atomic parameters were determined from synchrotron diffraction data, starting from a model that was obtained from single-crystal X-ray diffraction data. The anion lattice exhibits a rare ordering of oxide and chloride ions: one-dimensional zig-zag ladders of chlorine (squarelike motif) are surrounded by an oxygen matrix. Two different iron sites coordinated solely to oxygen are present in the structure, one octahedral and one square pyramidal, both distorted. Similarly, two different strontium coordinations are present; the first homoleptic coordinated to eight oxygen atoms and the second heteroleptic coordinated to four oxygen and four chlorine atoms in a fac-like manner. The lone pair of Te(IV) is directed toward the larger chlorine atoms. Magnetic susceptibility measurements confirm that Fe is +3 (d5) in the high-spin electronic configuration, exhibiting an almost ideal spin-only moment, μeff = 5.65 μB Fe–1. The slightly negative Weiss constant (θCW = −39 K) suggests dominating antiparallel spin-to-spin coupling in the paramagnetic temperature range, agreeing with an observed long-range antiferromagnetic spin ordering below Néel temperature, TN ∼ 13 K, and a broad second order-like anomaly in the specific heat measurement data. Low-temperature neutron diffraction data reveal that the antiferromagnetic ordered phase is C-type, with a k-vector (1/2, 1/2, 0) and ordered moment of 4.14(7) μB. The spin structure can be described as antiferromagnetic ordered layers stacked along the a-axis, forming layers of squares that alternate along the c-axis.

• Sannes, Johnny Andreas; Malayil, Ranjith K. Kizhake; Corredor, Laura T.; Wolter, Anja U. B.; Grafe, Hans-Joachim & Valldor, Björn Martin (2023). Synthesis and Characterization of Oxide Chloride Sr<inf>2</inf>VO<inf>3</inf>Cl, a Layered S = 1 Compound. ACS Omega. 8(15), s. 14233–14239. doi: 10.1021/acsomega.3c01151. Fulltekst i vitenarkiv Vis sammendrag

  The mixed-anion compound with composition Sr2VO3Cl has been synthesized for the first time, using the conventional high-temperature solid-state synthesis technique in a closed silica ampule under inert conditions. This compound belongs to the known Sr2TmO3Cl (Tm = Sc, Mn, Fe, Co, Ni) family, but with Tm = V. All homologues within this family can be described with the tetragonal space group P4/nmm (No. 129); from a Rietveld refinement of powder X-ray diffraction data on the Tm = V homologue, the unit cell parameters were determined to a = 3.95974(8) and c = 14.0660(4) Å, and the atomic parameters in the crystal structure could be estimated. The synthesized powder is black, implying that the compound is a semiconductor. The magnetic investigations suggest that Sr2VO3Cl is a paramagnet at high temperatures, exhibiting a μeff = 2.0 μB V–1 and antiferromagnetic (AFM) interactions between the magnetic vanadium spins (θCW = −50 K), in line with the V–O–V advantageous super-exchange paths in the V–O layers. Specific heat capacity studies indicate two small anomalies around 5 and 35 K, which however are not associated with long-range magnetic ordering. 35Cl ss-NMR investigations suggest a slow spin freezing below 4.2 K resulting in a glassy-like spin ground state.

• Gutterød, Emil Sebastian; Pulumati, S.H.; Kaur, Gurpreet; Lazzarini, Andrea; Solemsli, Bjørn Garding & Gunnæs, Anette Eleonora [Vis alle 13 forfattere av denne artikkelen] (2020). Influence of Defects and H2O on the Hydrogenation of CO2 to Methanol over Pt Nanoparticles in UiO-67 Metal-Organic Framework. Journal of the American Chemical Society. ISSN 0002-7863. 142(40), s. 17105–17118. doi: 10.1021/jacs.0c07153. Fulltekst i vitenarkiv Vis sammendrag

  In catalysts for CO2 hydrogenation, the interface between metal nanoparticles (NPs) and the support material is of high importance for the activity and reaction selectivity. In Pt NP-containing UiO Zr-metal–organic frameworks (MOFs), key intermediates in methanol formation are adsorbed at open Zr-sites at the Pt–MOF interface. In this study, we investigate the dynamic role of the Zr-node and the influence of H2O on the CO2 hydrogenation reaction at 170 °C, through steady state and transient isotope exchange experiments, H2O cofeed measurements, and density functional theory (DFT) calculations. The study revealed that an increased number of Zr-node defects increase the formation rates to both methanol and methane. Transient experiments linked the increase to a higher number of surface intermediates for both products. Experiments involving either dehydrated or prehydrated Zr-nodes showed higher methanol and methane formation rates over the dehydrated Zr-node. Transient experiments suggested that the difference is related to competitive adsorption between methanol and water. DFT calculations and microkinetic modeling support this conclusion and give further insight into the equilibria involved in the competitive adsorption process. The calculations revealed weaker adsorption of methanol in defective or dehydrated nodes, in agreement with the larger gas phase concentration of methanol observed experimentally. The microkinetic model shows that [Zr2(μ-O)2]4+ and [Zr2(μ–OH)(μ-O)(OH)(H2O)]4+ are the main surface species when the concentration of water is lower than the number of defect sites. Lastly, although addition of water was found to promote methanol desorption, water does not change the methanol steady state reaction rate, while it has a substantial inhibiting effect on CH4 formation. These results indicate that water can be used to increase the reaction selectivity to methanol and encourages further detailed investigations of the catalyst system.

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• Sannes, Johnny Andreas; Gonano, Bruno; Fjellvåg, Øystein Slagtern; Kumar, Susmit; Nilsen, Ola & Valldor, Björn Martin (2023). X-ray and neutron diffraction studies of SrTe2FeO6Cl, an oxide chloride with rare ordering of anions. Fulltekst i vitenarkiv
• Sannes, Johnny Andreas; Olsbye, Unni; Kalantzopoulos, Georgios N. & Arstad, Bjørnar (2020). CO2 adsorption and characterization of tailor-made metal-organic frameworks. Universitetet i Oslo. Fulltekst i vitenarkiv Vis sammendrag

  In this work, the 𝐶𝑂2adsorption capacityof chemically interesting metal-organic frameworks (MOFs) have been investigated. The MOFs have been characterized using standard inorganic/organic characterization tools such as pXRD, TGA, liquidand solid state NMR, SEM-EDS, static anddynamic gas adsorption.Potentially strong adsorption sites on the Pt–Zr interface was investigated by the use of TAP. The isosteric heat of adsorption have been estimated for UiO –67 as a function of pretreatment.A comparison of the isosteric heat of adsorption determined by the use of static and dynamic gas adsorption studies have been made.A two-step adsorption mechanismin the N2adsorption isotherm was observed for UiO –67 in the low pressure regime (𝑝𝑝0<0.005). The observed adsorption isothermshow resemblance to that of MOF –808, however occurring at a much lower pressure.UiO –67 and UiO –67 type MOFs have been investigated by the use of ss –NMR. A major effort was made towards the assignment of the peaks in therecorded1H and 13C spectrum of UiO –67. The work was leading to the hopeful elucidation of adsorption sites and adsorption orientations, however due to time constraint only the groundworkhave been performed.

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