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1.	Annamalai, Alagappan, et al. (författare) Influence of Sb5+ as a Double Donor on Hematite (Fe3+) Photoanodes for Surface-Enhanced Photoelectrochemical Water Oxidation 2018 Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 10:19, s. 16467-16473 Tidskriftsartikel (refereegranskat)abstract To exploit the full potential of hematite (α-Fe2O3) as an efficient photoanode for water oxidation, the redox processes occurring at the Fe2O3/electrolyte interface need to be studied in greater detail. Ex situ doping is an excellent technique to introduce dopants onto the photoanode surface and to modify the photoanode/electrolyte interface. In this context, we selected antimony (Sb5+) as the ex situ dopant because it is an effective electron donor and reduces recombination effects and concurrently utilize the possibility to tuning the surface charge and wettability. In the presence of Sb5+ states in Sb-doped Fe2O3 photoanodes, as confirmed by X-ray photoelectron spectroscopy, we observed a 10-fold increase in carrier concentration (1.1 × 1020 vs 1.3 × 1019 cm–3) and decreased photoanode/electrolyte charge transfer resistance (∼990 vs ∼3700 Ω). Furthermore, a broad range of surface characterization techniques such as Fourier-transform infrared spectroscopy, ζ-potential, and contact angle measurements reveal that changes in the surface hydroxyl groups following the ex situ doping also have an effect on the water splitting capability. Theoretical calculations suggest that Sb5+ can activate multiple Fe3+ ions simultaneously, in addition to increasing the surface charge and enhancing the electron/hole transport properties. To a greater extent, the Sb5+- surface-doped determines the interfacial properties of electrochemical charge transfer, leading to an efficient water oxidation mechanism.
2.	Asres, Georgies Alene, et al. (författare) Ultrasensitive H2S gas sensors based on p-type WS2 hybrid materials 2018 Ingår i: Nano Reseach. - : Springer. - 1998-0124 .- 1998-0000. ; 11:8, s. 4215-4224 Tidskriftsartikel (refereegranskat)abstract Owing to their higher intrinsic electrical conductivity and chemical stability with respect to their oxide counterparts, nanostructured metal sulfides are expected to revive materials for resistive chemical sensor applications. Herein, we explore the gas sensing behavior of WS2 nanowire-nanoflake hybrid materials and demonstrate their excellent sensitivity (0.043 ppm-1) as well as high selectivity towards H2S relative to CO, NH3, H2, and NO (with corresponding sensitivities of 0.002, 0.0074, 0.0002, and 0.0046 ppm-1, respectively). Gas response measurements, complemented with the results of X-ray photoelectron spectroscopy analysis and first-principles calculations based on density functional theory, suggest that the intrinsic electronic properties of pristine WS2 alone are not sufficient to explain the observed high sensitivity towards H2S. A major role in this behavior is also played by O doping in the S sites of the WS2 lattice. The results of the present study open up new avenues for the use of transition metal disulfide nanomaterials as effective alternatives to metal oxides in future applications for industrial process control, security, and health and environmental safety.
3.	Behravesh, Erfan, et al. (författare) Synthesis and characterization of Au nano particles supported catalysts for partial oxidation of ethanol : Influence of solution pH, Au nanoparticle size, support structure and acidity 2017 Ingår i: Journal of Catalysis. - : Elsevier. - 0021-9517 .- 1090-2694. ; 353, s. 223-238 Tidskriftsartikel (refereegranskat)abstract Partial oxidation of ethanol to acetaldehyde was carried out over gold catalysts supported on various oxides and zeolites by deposition precipitation. The special focus of this work was on the influence of H-Y zeolite surface charge on Au cluster size and loading linking it to activity and selectivity in ethanol oxidation and comparing with other studied catalysts. The catalysts were characterized by nitrogen physisorption, transmission electron microscopy (TEM), scanning electron microscopy/energy dispersive X-ray analysis (SEM/EDXA), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR) and zeta potential measurements. pH of the solution governed the Au NPs size within the range of 5.8–13.2 nm with less negatively charged surfaces leading to formation of smaller clusters. Au loading on H-Y zeolite with silica to alumina ratio of 80 was increased by raising the pH. In fact, H-Y-12 and H-Beta-25 were selective towards diethyl ether while acetaldehyde was the prevalent product on less acidic H-Y-80. The results demonstrated strong dependency of the catalytic activity on the Au cluster size. Namely turn over frequency (TOF) decreased with an increase in metal size from 6.3 to 9.3 nm on H-Y-80. Selectivity towards acetaldehyde and ethyl acetate did not change significantly on H-Y-80 within 6.3–9.3 nm Au particle size range. On Al2O3 support, however, selectivity towards acetaldehyde increased considerably upon diminishing Au average particle size from 3.7 to 2.1 nm.
4.	Biasi, P., et al. (författare) Revealing the role of bromide in the H2O2 direct synthesis with the catalyst wet pretreatment method (CWPM) 2017 Ingår i: AIChE Journal. - : American Institute of Chemical Engineers. - 0001-1541 .- 1547-5905. ; 63:1, s. 32-42 Tidskriftsartikel (refereegranskat)abstract A tailor-made Pd0/K2621 catalyst was subjected to post synthesis modiﬁcation via a wet treatment procedure. The aimwas the understanding of the role of promoters and how—if any—improvements could be qualitatively related to the cat-alyst performance for the H2O2direct synthesis. The Catalyst Wet Pretreatment Method was applied in different metha-nolic solutions containing H2O2, NaBr, and H3PO4, either as single modiﬁers or as a mixture. The catalyst wascharacterized by Transmission Electron Microscopy and X-ray Photoelectron Spectroscopy. It was concluded that themodiﬁed catalysts give rise to higher selectivities compared to the pristi ne reference catalyst thus opening a possibilityto exclude the addit ion of the undesirable selectivity enhancers in the reaction medium. This work provides original evi-dence on the role of promoter s, especially bromide, allowing the formulation of a new reaction mechanism for one ofthe most challenging reactions recognized by the world.
5.	Borah, Raju Kumar, et al. (författare) Copper Oxide Nanoparticles as a Mild and Efficient Catalyst for N-Arylation of Imidazole and Aniline with Boronic Acids at Room Temperature 2017 Ingår i: Synlett. - : Georg Thieme Verlag KG. - 0936-5214 .- 1437-2096. ; 28:10, s. 1177-1182 Tidskriftsartikel (refereegranskat)abstract The present work describes the excellent catalytic activity of copper(II) oxide nanoparticles (NPs) towards N-arylation of aniline and imidazole at room temperature. The copper(II) oxide NPs were synthesized by a thermal refluxing technique and characterized by FT-IR spectroscopy; powder XRD, SEM, EDX, TEM, TGA, XPS, BET surface area analysis, and particle size analysis. The size of the NPs was found to be around 12 nm having a surface area of 164.180 m(2) g(-1). The catalytic system was also found to be recyclable and could be reused in subsequent catalytic runs without a significant loss of activity.
6.	Bukhanko, Natalia, et al. (författare) Gas phase synthesis of isopropyl chloride from isopropanol and HCl over alumina and flexible 3-D carbon foam supported catalysts 2017 Ingår i: Applied Catalysis A. - : Elsevier. - 0926-860X .- 1873-3875. ; 542:25, s. 212-225 Tidskriftsartikel (refereegranskat)abstract Isopropyl chloride synthesis from isopropanol and HCl in gas phase over ZnCl2 catalysts supported on Al2O3 as well as flexible carbon foam was studied in a continuous reactor. A series of catalytic materials were synthesised and characterised by BET, XPS, SEM, TEM, XRD and NH3-TPD methods. Catalytic activity tests (product selectivity and conversion of reactants) were performed for all materials and optimal reaction conditions (temperature and feedstock flow rates) were found. The results indicate that the highest yield of isopropyl chloride was obtained over 5 wt.% ZnCl2 on commercial Al2O3 (No. II) (95.3%). Determination of product mixture compositions and by-product identification were done using a GC-MS method. Carbon foam variant catalyst, 5 wt.% ZnCl2/C, was found to perform best out of the carbon-supported materials, achieving ∼75% yield of isopropyl chloride. The kinetic model describing the process in a continuous packed bed reactor was proposed and kinetic parameters were calculated. The activation energy for the formation of isopropyl chloride reaction directly from isopropanol and HCl was found to be ∼58 kJ/mol.
7.	Cano, A., et al. (författare) Contribution to the coordination chemistry of transition metal nitroprussides : a cryo-XPS study 2019 Ingår i: New Journal of Chemistry. - : Royal Society of Chemistry. - 1144-0546 .- 1369-9261. ; 43:12, s. 4835-4848 Tidskriftsartikel (refereegranskat)abstract The series of coordination polymers under investigation was formed by the assembly of a pentacyanonitrosylferrate(ii) anionic block, [Fe(CN)(5)NO](2-), through monovalent and divalent transition metal ions, e.g. Mn2+, Fe2+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+, Hg2+ and Ag+. For divalent ions, the resulting materials have a 3D porous framework with attractive features for applications in gas storage and separation, as electroactive solids, light-driven molecular magnets, and so on; in this study, we report the results obtained for a series of coordination polymers using the cryogenic X-ray photoelectron spectroscopy (cryo-XPS) data; comprehensive details regarding their coordination chemistries were obtained from the acquired spectra in addition to their comparison with the structural and spectroscopic information obtained from other techniques. The results discussed herein are original and contribute towards the understanding of the electronic structures and related properties for this family of coordination polymers. This series of solids was found to be highly susceptible to strong damage induced by X-ray beams throughout the conventional XPS experiment; therefore, the analysis was conducted under cryogenic conditions.
8.	Cano, A., et al. (författare) Intercalation of pyrazine in layered copper nitroprusside : synthesis, crystal structure and XPS study 2019 Ingår i: Journal of Solid State Chemistry. - : Elsevier. - 0022-4596 .- 1095-726X. ; 273, s. 1-10 Tidskriftsartikel (refereegranskat)abstract Hybrid inorganic–organic solids form an interesting family of functional materials, where their functionalities are determined by both, the inorganic and organic building blocks. This study reports the intercalation of pyrazine in 2D copper nitroprusside, the crystal structure of the resulting hybrid solid and explores the scope of cryogenic X-ray photoelectron spectroscopy (XPS) to shed light on its electronic structure. In this material, the pyrazine molecule appears coordinated to Cu atoms from neighboring layers, to form the columns in the resulting 3D porous framework. Its crystal structure was solved and refined from the corresponding XRD powder pattern. XPS data, recorded under cryogenic conditions, provided fine details on the electronic structure of this hybrid solid. The binding energy values for the ligand atoms and the involved metals show a definite correlation with the structural data and FT-IR spectra. When XPS spectra were recorded at room temperature, a significant sample decomposition was observed. Three possible mechanisms for the sample damage during the XPS experiment are considered. The hybrid material under study is representative of a wide series of nanoporous solids obtained by intercalation of organic pillars between 2D inorganic solids.
9.	Das, Vijay Kumar, et al. (författare) A convenient 'NOSE' approach used towards the synthesis of 6-amino-1,3-dimethyl-5-indolyl-1H-pyrimidine-2,4-dione derivatives catalyzed by nano-Ag 2016 Ingår i: New Journal of Chemistry. - : Royal Society of Chemistry. - 1144-0546 .- 1369-9261. ; 40:3, s. 1935-1939 Tidskriftsartikel (refereegranskat)abstract An endeavour has been made towards the synthesis of uracil based compounds in good to high yield catalyzed by nano-Ag at 70 [degree]C upon reacting 6-amino-1,3-dimethyluracil and indole derivatives. The catalyst was potentially recyclable from fresh up to the third run.
10.	Davidovich, P. B., et al. (författare) Synthesis and structure of dinitrosyl iron complexes with secondary thiolate bridging ligands [Fe-2(mμ-SCHR2)(2)(NO)(4)], R = Me, Ph 2015 Ingår i: Polyhedron. - : Elsevier. - 0277-5387 .- 1873-3719. ; 90, s. 197-201 Tidskriftsartikel (refereegranskat)abstract New dinitrosyl iron complexes of binuclear structure [Fe-2(mu-SCHMe2)(2)(NO)(4)] and [Fe-2(mu-SCHPh2)(2)(NO)(4)] were first synthesized employing new method from Fe(CO)(5), corresponding thiol, and EtONO. Complexes structures were determined by XRD technique. DFT calculations were performed to probe the cis-conformer structures in gas and solution phases. NO donor ability of the complex with isopropyl thiolate ligand was studied.
11.	Davidovich, P. B., et al. (författare) Synthesis, structure, biochemical, and docking studies of a new dinitrosyl iron complex [Fe-2(mu-SC4H3SCH2)(2)(NO)(4)] 2015 Ingår i: Journal of Molecular Structure. - : Elsevier BV. - 0022-2860 .- 1872-8014. ; 1092, s. 137-142 Tidskriftsartikel (refereegranskat)abstract A new dinitrosyl iron complex of binuclear structure [Fe-2(mu-S-2-methylthiophene)(2)(NO)(4)] was first synthesized and structurally characterized by XRD and theoretical methods. Using caspase-3 as an example it was shown that [Fe-2(mu-S-2-methylthiophene)(2)(NO)(4)] and its analog [Fe-2(mu-S-2-methylfurane)(2)(NO)(4)] can inhibit the action of active site cysteine proteins; the difference in inhibitory activity was explained by molecular docking studies. Biochemical and in silico studies give grounds that the biological activity of dinitrosyl iron complexes is a mu-SR bridging ligand structure function. Thus the rational design strategy of [Fe-2(mu-SR)(2)(NO)(4)] complexes can be applied to make NO prodrugs with high affinity to therapeutically significant targets involved in cancer and inflammation.
12.	Ekspong, Joakim, et al. (författare) Stabilizing Active Edge Sites in Semicrystalline Molybdenum Sulfide by Anchorage on Nitrogen-Doped Carbon Nanotubes for Hydrogen Evolution Reaction 2016 Ingår i: Advanced Functional Materials. - : Wiley-VCH Verlagsgesellschaft. - 1616-301X .- 1616-3028. ; 26:37, s. 6766-6776 Tidskriftsartikel (refereegranskat)abstract Finding an abundant and cost-effective electrocatalyst for the hydrogen evolu-tion reaction (HER) is crucial for a global production of hydrogen from water electrolysis. This work reports an exceptionally large surface area hybrid catalyst electrode comprising semicrystalline molybdenum sulﬁ de (MoS 2+ x) catalystattached on a substrate based on nitrogen-doped carbon nanotubes (N-CNTs), which are directly grown on carbon ﬁber paper (CP). It is shown here that nitrogen-doping of the carbon nanotubes improves the anchoring of MoS 2+ xcatalyst compared to undoped carbon nanotubes and concurrently stabilizes a semicrystalline structure of MoS 2+ x with a high exposure of active sites for HER. The well-connected constituents of the hybrid catalyst are shown to facilitate electron transport and as a result of the good attributes, the MoS 2+ x/N-CNT/CPelectrode exhibits an onset potential of −135 mV for HER in 0.5 M H2SO4, a Tafel slope of 36 mV dec −1, and high stability at a current density of −10 mA cm −2.
13.	Gemo, Nicola, et al. (författare) The influence of catalyst amount and Pd loading on the H2O2 synthesis from hydrogen and oxygen 2015 Ingår i: Catalysis Science & Technology. - : Royal Society of Chemistry (RSC). - 2044-4753 .- 2044-4761. ; 5:7, s. 3545-3555 Tidskriftsartikel (refereegranskat)abstract Palladium catalysts with an active metal content from 0.3 to 5.0 wt.% and supported on a strongly acidic, macroporous resin were prepared by ion-exchange/reduction method. H2O2 direct synthesis was carried out in the absence of promoters (acids and halides). The total Pd amount in the reacting environment was varied by changing A) the catalyst concentration in the slurry and B) the Pd content of the catalyst. In both cases, smaller amounts of the active metal enhance the selectivity towards H2O2, at any H-2 conversion, with option B) better than A). In case A), the Pd(II)/Pd(0) molar ratio (XPS) in the spent catalysts was found to decrease at lower catalyst Pd content. With these catalysts and this experimental set-up the dynamic H-2(1)/Pd molar ratio, the metal loading and the metal particle size were the key factors controlling the selectivity, which reached 57% at 60% H-2 conversion, and 80% at lower conversion.
14.	Gemo, Nicola, et al. (författare) TiO2 nanoparticles vs. TiO2 nanowires as support in hydrogen peroxide direct synthesis : the influence of N and Au doping 2016 Ingår i: RSC Advances. - : Royal Society of Chemistry. - 2046-2069. ; 6:105, s. 103311-103319 Tidskriftsartikel (refereegranskat)abstract The performance of Pd on titania support were evaluated in the direct synthesis of hydrogen peroxide. The equipment used was a high pressure, semi-batch apparatus equipped with a special injection system. Pd (1 wt%) catalysts on TiO2 materials with different nature were prepared by wet impregnation method. Three aspects were investigated: (a) the structure of the support (nanoparticles vs. nanowires); (b) the addition of a second active metal (Au); (c) the influence of N-doping of the support. All samples were characterized by means of XPS, TEM and XRD analyses. TiO2 nanoparticle supported catalyst demonstrated higher H2O2 selectivity and higher turnover frequency (TOF) than the catalysts based on TiO2 nanowires. The addition of Au to the Pd TiO2 nanowire catalyst improved the H2O2 selectivity due to altered particle size and electronic effects. Both N-doped versions of the catalysts gave rise to higher H2O2 selectivity than the parent non-doped ones. The synthetic procedure was the source of this observation: larger mean Pd nanoparticles were present, thus favouring the formation of H2O2 as the primary product.
15.	Gustafson, Karl P. J., et al. (författare) Chemoenzymatic Dynamic Kinetic Resolution of Primary Benzylic Amines using Pd-0-CalB CLEA as a Biohybrid Catalyst 2019 Ingår i: Chemistry - A European Journal. - : Wiley. - 0947-6539 .- 1521-3765. ; 25:39, s. 9174-9179 Tidskriftsartikel (refereegranskat)abstract Herein, we report on the use a biohybrid catalyst consisting of palladium nanoparticles immobilized on cross-linked enzyme aggregates of lipase B of Candida antarctica (CalB CLEA) for the dynamic kinetic resolution (DKR) of benzylic amines. A set of amines were demonstrated to undergo an efficient DKR and the recyclability of the catalysts was studied. Extensive efforts to further elucidate the structure of the catalyst are presented.
16.	Konwar, Lakhya Jyoti, et al. (författare) Sustainable synthesis of N and P co-doped porous amorphous carbon using oil seed processing wastes 2016 Ingår i: Materials letters (General ed.). - : Elsevier. - 0167-577X .- 1873-4979. ; 173, s. 145-148 Tidskriftsartikel (refereegranskat)abstract Abstract A facile approach for the sustainable synthesis of amorphous carbons co-doped with N and P (NC) was demonstrated using inexpensive protein rich wastes and H3PO4 as precursors. The prepared NC materials exhibited high degree of aromatization, porosity (specific surface area 435–915 m2/g, pore volume 0.34–0.66 cm3/g) and nitrogen doping levels of 3.4–9.8 at%, depending on intrinsic properties of precursor and synthesis conditions. The materials exhibited electro-catalytic activity for oxygen reduction reaction (ORR) in alkaline electrolytes.
17.	Kwong, Wai Ling, et al. (författare) Cobalt- doped hematite thin films for electrocatalytic water oxidation in highly acidic media 2019 Ingår i: Chemical Communications. - : The Royal Society of Chemistry. - 1359-7345 .- 1364-548X. ; 55:34, s. 5017-5020 Tidskriftsartikel (refereegranskat)abstract Earth-abundant cobalt-doped hematite thin-film electrocatalysts were explored for acidic water oxidation. The strategically doped hematite produced a stable geometric current density of 10 mA cm(-2) for up to 50 h at pH 0.3, as a result of Co-enhanced intrinsic catalytic activity and charge transport properties across the film matrix.
18.	Kwong, Wai Ling, et al. (författare) High-performance iron (III) oxide electrocatalyst for water oxidation in strongly acidic media 2018 Ingår i: Journal of Catalysis. - : Academic Press. - 0021-9517 .- 1090-2694. ; 365, s. 29-35 Tidskriftsartikel (refereegranskat)abstract Stable and efficient oxygen evolution reaction (OER) catalysts for the oxidation of water to dioxygen in highly acidic media are currently limited to expensive noble metal (Ir and Ru) oxides since presently known OER catalysts made of inexpensive earth-abundant materials generally suffer anodic corrosion at low pH. In this study, we report that a mixed-polymorph film comprising maghemite and hematite, prepared using spray pyrolysis deposition followed by low-temperature annealing, showed a sustained OER rate (>24 h) corresponding to a current density of 10 mA cm−2 at an initial overpotential of 650 mV, with a Tafel slope of only 56 mV dec−1 and near-100% Faradaic efficiency in 0.5 M H2SO4 (pH 0.3). This performance is remarkable, since iron (III) oxide films comprising only maghemite were found to exhibit a comparable intrinsic activity, but considerably lower stability for OER, while films of pure hematite were OER-inactive. These results are explained by the differences in the polymorph crystal structures, which cause different electrical conductivity and surface interactions with water molecules and protons. Our findings not only reveal the potential of iron (III) oxide as acid-stable OER catalyst, but also highlight the important yet hitherto largely unexplored effect of crystal polymorphism on electrocatalytic OER performance.
19.	Li, Man-Bo, et al. (författare) Diastereoselective Cyclobutenol Synthesis : A Heterogeneous Palladium-Catalyzed Oxidative Carbocyclization-Borylation of Enallenols 2019 Ingår i: Chemistry - A European Journal. - : Wiley. - 0947-6539 .- 1521-3765. ; 25:1, s. 210-215 Tidskriftsartikel (refereegranskat)abstract A highly selective and efficient oxidative carbocyclization/borylation of enallenols catalyzed by palladium immobilized on amino-functionalized siliceous mesocellular foam (Pd-AmP-MCF) was developed for diastereoselective cyclobutenol synthesis. The heterogeneous palladium catalyst can be recovered and recycled without any observed loss of activity or selectivity. The high diastereoselectivity of the reaction is proposed to originate from a directing effect of the enallenol hydroxyl group. Optically pure cyclobutenol synthesis was achieved by the heterogeneous strategy by using chiral enallenol obtained from kinetic resolution.
20.	Lucas, Marie, et al. (författare) X-ray photoelectron spectroscopy of fast-Frozen hematite colloids in aqueous solutions. 6. Sodium halide (F–, Cl–, Br–, I–) ion binding on microparticles 2018 Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 34:45, s. 13497-13504 Tidskriftsartikel (refereegranskat)abstract Electrolyte ion binding at mineral surfaces is central to the generation of surface charge and key to electric double-layer formation. X-ray photoelectron spectroscopy of fast-frozen (−170 °C) mineral wet pastes provides a means to study weakly bound electrolyte ions at the mineral/water interface. In this study, we build upon a series of articles devoted to ion binding at hematite (α-Fe2O3) particle surfaces to resolve the nature of sodium halide ion binding. Measurements on micron-sized hematite particles terminated by the charged and amphoteric (012) and the relatively uncharged (001) faces point to the formation of salt loadings of similar composition to those of cryosalts of NaCl, NaBr, NaI, and NaF. These coatings could be likened to those of the better-known hydrohalite (NaCl·2H2O) phase, one that typically forms under concentrated (≫0.1 M) aqueous solutions of NaCl under freezing conditions. As we have previously shown that these reaction products do not occur in nanosized hematite particles, our work points to the involvement of the basal (001) face and/or the juxtaposition of these faces in packed tabular microparticles of hematite (1–3 μm in width) in stabilizing these cryosalts. One possible formation pathway involves first-layer Na+ and Cl– ions serving as an anchoring layer for a topotactic-like growth of amorphous to low-crystalline salt hydrates at the (001) face. Thus, by contrasting reaction products of four sodium halides at surfaces of tabular microparticles of hematite, this work revealed the formation of cryosalt-like solids. The formation of such solids may have especially important ramifications to ice nucleation mechanisms in the atmosphere, as well as in saline permafrosts on Earth and on planet Mars where salt-laden mineral particles prevail.
21.	Martin, Sebastien, et al. (författare) Kinetics and Mechanisms of Ciprofloxacin Oxidation on Hematite Surfaces 2015 Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 49:20, s. 12197-12205 Tidskriftsartikel (refereegranskat)abstract Adsorption of antibiotics at mineral surfaces has been extensively studied over the past 20 years, yet much remains to be learned on their interfacial properties and transformation mechanisms. In this study, interactions of Ciprofloxacin (CIP), a fluoroquinolone antibiotic with two sets of synthetic nanosized hematite particles, with relatively smooth (H10, 10-20 nm in diameter) and roughened (H80, 80-90 nm in diameter) surfaces, were studied by means of liquid chromatography (LC), mass spectrometry (MS), and spectroscopy (vibration and X-ray photoelectron). Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) spectroscopy provides evidence for inner-sphere bidentate complex formation of CIP at hematite surfaces in 0.01 M NaCl, irrespective of pH and particle size. ATR-FTIR spectroscopy also revealed that the sorbed mother CIP molecule decayed to other surface species over a period of at least 65 h. This was supported by the detection of three daughter products in the aqueous phase by LC/MS. The appearance of NH3+ groups during the course of these experiments, revealed by cryogenic XPS, provides further evidence that CIP oxidation proceeds through an opening of piperazine ring via N-dealkylation. Additional in vacuo FTIR experiments under temperature-programmed desorption also showed that oxidation of sorbed byproducts were effectively degraded beyond 450 degrees C, a result denoting considerably strong (inter)molecular bonds of both mother and daughter products. This work also showed that rougher, possibly multidomainic particles (H80) generated slower rates of CIP decomposition but occurring through more complex schemes than at smoother particle surfaces (H10). This work thus uncovered key aspects of the binding of an important antibiotic at iron oxide surfaces, and therefore provided additional constraints to our growing understanding of the fate of emerging contaminants in the environment.
22.	Masoud, Taheri, et al. (författare) A comparison between two Pd‐Ni catalysts supported on two different supports toward Suzuki‐Miyaura coupling reaction 2018 Ingår i: Applied organometallic chemistry. - : Wiley-Blackwell. - 0268-2605 .- 1099-0739. ; 32:5 Tidskriftsartikel (refereegranskat)abstract When a single metal fails to promote an efficient Suzuki?Miyaura coupling reaction at ambient temperature, the synergistic cooperation of two distinct metals might improve the reaction. To examine the synergistic effect of palladium and nickel for catalyzing Suzuki coupling reaction, g?C3N4 supported metal nanoparticles of PdO, NiO and Pd?PdO?NiO were prepared, characterized and their catalytic activities evaluated over different aryl halides at room temperature and 78 °C. The morphological characterization of Pd?PdO?NiO/g?C3N4 demonstrated that the bimetallic particles were uniformly dispersed over the g?C3N4 layers with diameters ranging from 3.5?7.7 nm. XPS analysis showed that nanoparticles of Pd?PdO?NiO consisted of Pd(II), Pd(0) and Ni(II) sites. The experiments performed on the catalytic activity of Pd?PdO?NiO/g?C3N4 showed that the prepared catalyst demonstrated an efficient activity without using toxic solvents.
23.	Mikhlin, Yuri, et al. (författare) Cryogenic XPS study of fast-frozen sulfide minerals : Flotation-related adsorption of n-butyl xanthate and beyond 2016 Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - : Elsevier BV. - 0368-2048 .- 1873-2526. ; 206, s. 65-73 Tidskriftsartikel (refereegranskat)abstract Cryogenic XPS of wet particulate samples separated via centrifugation and fast-frozen allows quasi in situ examination of solid surfaces, adsorbates, and reaction products, largely preventing the loss both of volatiles and hydrated species at mineral/water interfaces. Here, the cryo-XPS has been applied to characterize the surfaces and interfacial layers of natural pyrite (FeS2), chalcopyrite (CuFeS2), and galena (PbS) in solutions of a common flotation collector, potassium n-butyl xanthate (KBX), in conjunction with zeta-potential measurement. It was found, in particular, that dibutyl dixanthogen was the major adsorbate at pyrite in 0.1 mM KBX and 10 mM KBX solutions; dixanthogen and cuprous xanthate in the next stage were formed on chalcopyrite, and predominant chemisorbed butyl xanthate was present at galena, including in 10 mM KBX solution. The results may suggest that the production of dixanthogens at the interface has been underestimated while the quantities of surface metal xanthates could be over evaluated in previous studies. Pronounced differential charging effects were observed in the XPS experiment for the samples moderately hydrophobized by the xanthate treatment; we proposed that the effect was due to electrically isolated mineral particles with hydrophobic and ice-repellent surfaces, which retained, however, some frozen water islets.
24.	Mikhlin, Yuri, et al. (författare) Interaction of sphalerite with potassium n-butyl xanthate and copper sulfate solutions studied by XPS of fast-frozen samples and zeta-potential measurement 2016 Ingår i: Vacuum. - : Elsevier BV. - 0042-207X .- 1879-2715. ; 125, s. 98-105 Tidskriftsartikel (refereegranskat)abstract We acquired low-temperature X-ray photoelectron spectra of fast-frozen wet pastes prepared by centrifugation of the natural sphalerite slurries containing potassium n-butyl xanthate (KBX), without washing or any additional treatment, before and after the mineral activation in 0.1 mM CuSO4 solution. Zeta potentials of the slurry particles were also measured. The method allowed characterizing the mineral surfaces and adsorbates, volatile substances and hydrated species within the interfacial layers under more realistic flotation-related conditions. The uptake of xanthate by unactivated mineral was low even in 10 mM KBX, while the surface became metal-deficient (enriched in sulfur), more hydrophobic and contaminated with carbonaceous matter. Dibutyl dixanthogen was the major interfacial product of the interaction of Cu-activated sphalerite having the surface atomic Zn/Cu ratio of 3 and excess of sulfur with the KBX solutions. The spectra revealed only minor quantities of Zn and Cu xanthates and oxyhydroxides at all the samples; some hydrated K+ counter-ions were detected at the negatively charged surfaces after the xanthate treatment. The dixanthogen was concluded to form via oxidation of xanthate at the interface, probably catalyzed by surface cuprous species but not direct interaction with cupric ions.
25.	Ngoc Pham, Tung, et al. (författare) Robust hierarchical 3D carbon foam electrode for efficient water electrolysis 2017 Ingår i: Scientific Reports. - : Nature Publishing Group. - 2045-2322. ; 7 Tidskriftsartikel (refereegranskat)abstract Herein we report a 3D heterostructure comprising a hierarchical macroporous carbon foam that incorporates mesoporous carbon nanotubes decorated with cobalt oxide nanoparticles as an unique and highly efficient electrode material for the oxygen evolution reaction (OER) in electrocatalytic water splitting. The best performing electrode material showed high stability after 10 h, at constant potential of 1.7 V vs. RHE (reversible hydrogen electrode) in a 0.1 M KOH solution and high electrocatalytic activity in OER with low overpotential (0.38 V vs RHE at 10 mA cm(-2)). The excellent electrocatalytic performance of the electrode is rationalized by the overall 3D macroporous structure and with the firmly integrated CNTs directly grown on the foam, resulting in a large specific surface area, good electrical conductivity, as well as an efficient electrolyte transport into the whole electrode matrix concurrent with an ability to quickly dispose oxygen bubbles into the electrolyte. The eminent properties of the three-dimensional structured carbon matrix, which can be synthesized through a simple, scalable and cost effective pyrolysis process show that it has potential to be implemented in large-scale water electrolysis systems.
26.	Nuri, Ayat, et al. (författare) Magnetic Mesoporous SBA-15 Functionalized with a NHC Pd(II) Complex : An Efficient and Recoverable Nanocatalyst for Hiyama Reaction 2019 Ingår i: ChemistrySelect. - : Wiley. - 2365-6549. ; 4:5, s. 1820-1829 Tidskriftsartikel (refereegranskat)abstract Magnetite nanoparticles (MNPs) were covered by a silica shell and then embedded into mesoporous silica (SBA‐15). Magnetic mesoporous silica (Fe3O4@SiO2‐SBA) was then reacted with 3‐chloropropyltriethoxysilane (CPTS), sodium salt of imidazole and 2‐bromopyridine to give Fe3O4@SiO2‐SBA functionalized with 3‐(pyridin‐2‐yl)‐1H‐imidazol‐3‐ium‐propyl (PIP) as a supported pincer ligand for Pd(II). The functionalized magnetic mesoporous silica were then treated with t‐BuOK at −80 °C in THF and then reacted with [PdCl2(SMe2)2] to give supported Pd(II)‐carbene complex containing C,N‐bidentate ligand. The chloride ions were then exchanged by bromide ions using a NaBr solution of diethylether/acetone mixture. The prepared catalyst was characterized with, FT‐IR, thermo gravimetric analysis (TGA), scanning electron microscopy (SEM), transmission electron microscopy (TEM), vibrating sample magnetometry (VSM), Brunauer–Emmett–Teller surface area measurement (SBET), energy dispersive X‐ray analysis (EDX) and wide angle X‐ray diffraction spectroscopy (XRD). The prepared magnetic catalyst was effectively used in the coupling reaction of triethoxyphenylsilane with aryl halides (Hiyama reaction) in the presence of a base. The reaction parameters such as solvents, amount of catalyst, base and temperature were optimized. The catalyst was then magnetically decanted, washed, and reused several times.
27.	Phal, Sereilakhena, et al. (författare) Determination of methotrexate in spiked human blood serum using multi-frequency electrochemical immittance spectroscopy and multivariate data analysis 2017 Ingår i: Analytica Chimica Acta. - : Elsevier. - 0003-2670 .- 1873-4324. ; 987, s. 15-24 Tidskriftsartikel (refereegranskat)abstract This article describes an attempt to develop a sensor based on multi-frequency immittance spectroscopy for the determination of methotrexate (MTX) in blood serum using gold electrodes modified with antibodies. The attachment of antibodies was monitored with electrochemical immittance spectroscopy (EIS) and X-ray photoelectron spectroscopy (XPS). The EIS measurements of MTX resulted in a data matrix of size 39 × 55. The data were analysed using multivariate data analysis and showed a concentration dependence and time dependence that could be separated. This allowed the calculation of a multivariate calibration model. The model showed good linear behavior on a logarithmic scale offering a detection limit of 5 × 10−12 mol L−1.
28.	Ramstedt, Madeleine, et al. (författare) Analysis of bacterial cell surface chemical composition using cryogenic X-ray photoelectron spectroscopy 2016 Ingår i: Bacterial cell wall homeostasis. - New York, NY : Humana Press. - 9781493936762 - 9781493936748 ; , s. 215-223 Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract This chapter describes a method for measuring the average surface chemical composition with respect to lipids, polysaccharides, and peptides (protein + peptidoglycan) for the outer part of the bacterial cell wall. Bacterial cultures grown over night are washed with a buffer or saline at controlled pH. The analysis is done on fast-frozen bacterial cell pellets obtained after centrifugation, and the analysis requires access to X-ray photoelectron spectroscopy instrumentation that can perform analyses at cryogenic temperatures (for example using liquid nitrogen). The method can be used to monitor changes in the cell wall composition following environmental stimuli or genetic mutations. The data obtained originate from the outermost part of the cell wall. Thus, it is expected that for gram-negative bacteria only the outer membrane and part of the periplasmic peptidoglycan layer is probed during analysis, and for gram-positive bacteria only the top nanometers of the peptidoglycan layer of the cell wall is monitored.
29.	Ramstedt, Madeleine, et al. (författare) Bacterial surfaces in geochemistry : how can x-ray photoelectron spectroscopy help? 2019 Ingår i: Analytical geomicrobiology. - Cambridge : Cambridges Institutes Press. - 9781107070332 - 9781107707399 ; , s. 262-287 Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract Processes occurring at surfaces and interfaces are very important in environmental systems, necessitating surface-specific characterization tools that can help us understand processes at and specific properties of surfaces and interfaces, and their role in biogeochemical systems. This chapter describes the use and application of X-ray photoelectron spectroscopy (XPS) to study interfacial processes of relevance for geomicrobiology. Examples are given from studies determining cell wall composition, acid–base properties, cell surface charge, metal adsorption onto bacterial cells, and bacterial surface–induced precipitation of secondary minerals. As XPS is an ultrahigh-vacuum technique, several sample preparation methods have been applied to enable analysis of bacterial samples, including analysis of freeze-dried samples as well as frozen bacterial suspensions. These are described and discussed alongside advantages and disadvantages of different approaches, with a special focus on fast-freezing and the cryogenic technique.
30.	Riittonen, Toni, et al. (författare) Continuous liquid-phase valorization of bio-ethanol towards bio-butanol over metal modified alumina 2015 Ingår i: Renewable energy. - : Elsevier. - 0960-1481 .- 1879-0682. ; 74, s. 369-378 Tidskriftsartikel (refereegranskat)abstract Commercial mixed-phase aluminum oxide was used as a heterogeneous catalyst support, providing slightly basic properties which are well-suited for the condensation of bio-ethanol to C-4 hydrocarbons, such as 1-butanol. Different metals (Cu, Ni and Co), at various metal loadings were deposited on the support. Consequently, the catalytic reactions were carried out in a continuous laboratory-scale fixed bed reactor operated at 240 degrees C and 70 bar. The catalysts were characterized by means of XRD, TEM, FT-IR, XPS and ICP-OES. Different metals were found to give entirely different product distributions. With the best catalysts, the selectivities towards 1-butanol close to 70% were reached, while the ethanol conversion typically varied between 10 and 30% - strongly depending on the metal applied. It was observed that low loading of copper and high loading of nickel were responsible for the formation of 1-butanol, whereas cobalt and high loading of copper resulted in the production of ethyl acetate. The reaction was found to be extremely sensitive to catalyst preparation conditions and procedures such as metal loading, calcination/reduction temperature and, thereby, to the formation of corresponding crystallite structure.
31.	Sandström, Robin, et al. (författare) Yttria stabilized and surface activated platinum (PtxYOy) nanoparticles through rapid microwave assisted synthesis for oxygen reduction reaction 2018 Ingår i: Nano Energy. - : Elsevier. - 2211-2855 .- 2211-3282. ; 46, s. 141-149 Tidskriftsartikel (refereegranskat)abstract The enhancement of platinum (Pt) based catalysts for the oxygen reduction reaction (ORR) by addition of rare earth metals represents a promising strategy to achieve high activity yet low content of the precious metal and concurrently addresses stability issues experienced by traditional late transition metal doping. Improvement in Pt utilization is essential for vehicular applications where material cost and abundancy is a great concern. Here we report a fast and efficient production route of yttria-stabilized platinum nanoparticles (PtxYOy) using a conventional household microwave oven. ORR performance showed a significant improvement and an optimum activity at a 3:1 Pt:Y ratio outperforming that of commercial Pt-Vulcan with a doubled specific activity. Incorporation of Y is evidenced by extended X-ray absorption fine structure and energy dispersive X-ray analysis, while significant amounts of integrated Y2O3 species are detected by X-ray photoelectron spectroscopy. Density functional theory calculations suggest surface migration and oxidation of Y, forming stable superficial yttrium oxide species with low negative enthalpies of formation. The robustness of PtxYOy is shown experimentally and through theoretical arguments demonstrating that surface yttria acts as a stabilizing agent and promoter of highly active ORR sites on the remaining Pt surface, surpassing even the Pt3Y alloy configuration.
32.	Sarkar, Anjana, et al. (författare) Photocatalytic reduction of CO2 with H2O over modified TiO2 nanofibers : Understanding the reduction pathway 2016 Ingår i: Nano Reseach. - : Springer Science+Business Media B.V.. - 1998-0124 .- 1998-0000. ; , s. 1-13 Tidskriftsartikel (refereegranskat)abstract Nanosized metal (Pt or Pd)-decorated TiO2 nanofibers (NFs) were synthesized by a wet impregnation method. CdSe quantum dots (QDs) were then anchored onto the metal-decorated TiO2 NFs. The photocatalytic performance of these catalysts was tested for activation and reduction of CO2 under UV-B light. Gas chromatographic analysis indicated the formation of methanol, formic acid, and methyl formate as the primary products. In the absence of CdSe QDs, Pd-decorated TiO2 NFs were found to exhibit enhanced performance compared to Pt-decorated TiO2 NFs for methanol production. However, in the presence of CdSe, Pt-decorated TiO2 NFs exhibited higher selectivity for methanol, typically producing ∼90 ppmg−1·h−1 methanol. The CO2 photoreduction mechanism is proposed to take place via a hydrogenation pathway from first principles calculations, which complement the experimental observations.
33.	Shchukarev, Andrey, et al. (författare) Cryo-XPS : probing intact interfaces in nature and life 2017 Ingår i: Surface and Interface Analysis. - : John Wiley & Sons. - 0142-2421 .- 1096-9918. ; 49:4, s. 349-356 Tidskriftsartikel (refereegranskat)abstract Experimental studies of solid–aqueous solution interfaces are of great importance for reaching a better chemical understanding ofinterfacial phenomena at the molecular level. This perspective article presents a recently developed approach for investigation ofintact interfaces, based on fast freezing of centrifuged wet pastes followed by traditional XPS measurements at liquid nitrogentemperatures. Sample preparation and handling protocols, applicable to any suspension or gel, are discussed in detail. For mineralsuspensions, cryogenic XPS is an important complement to traditional analyses of supernatant solutions and dry solids that iscapable of revealing novel insights of the electrical double layer in terms of structure and composition. It can be used to studychanges in the biochemistry of bacterial cell walls as influenced by external stimuli, and interfacial features related tobiocompatibility of implant materials. Herein we review how the technique has been applied to minerals in electrolyte solutions,intact bacterial surfaces, and biomaterial interfaces in biologically relevant media, and highlight some future requirements fordevelopment of interface analysis methodologies.
34.	Shchukarev, Andrey, et al. (författare) Surface characterization of insulin-coated Ti6Al4V medical implants conditioned in cell culture medium: An XPS study 2017 Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - : Elsevier BV. - 0368-2048 .- 1873-2526. ; 216, s. 33-38 Tidskriftsartikel (refereegranskat)abstract © 2017 Elsevier B.V.Surface characterization of insulin-coated Ti6Al4V medical implants, after incubation in α-minimum essential medium (α-MEM), was done by X-ray photoelectron spectroscopy (XPS), in order to analyze the insulin behavior at the implant – α-MEM interface. In the absence of serum proteins in cell culture medium, the coated insulin layer remained intact, but experienced a time-dependent structural transformation exposing hydrophobic parts of the protein toward the solution. The presence of fetal bovine serum (FBS) in the medium resulted in partial substitution of insulin by serum proteins. In spite of some insulin release, the remaining coated layer demonstrated a direct surface effect by stabilizing the structure of protein competitors, and by supporting the accumulation of calcium and phosphate ions at the interface. A structurally stable protein layer with incorporated calcium and phosphate ions at the implant–tissue interface could be an important prerequisite for enhanced bone formation.
35.	Shimizu, Kenichi, et al. (författare) Bifluoride ([HF2](-)) formation at the fluoridated aluminium hydroxide/water interface 2016 Ingår i: Dalton Transactions. - : Royal Society of Chemistry (RSC). - 1477-9226 .- 1477-9234. ; 45:22, s. 9045-9050 Tidskriftsartikel (refereegranskat)abstract This study uncovers bifluoride-type (difluorohydrogenate(I); [HF2](-)) species formed at mineral/water interfaces. Bifluoride forms at equivalent to Al-F surface sites resulting from the partial fluoridation of gibbsite (gamma-Al(OH3)) and bayerite (alpha-Al(OH3)) particles exposed to aqueous solutions of 50 mM NaF. Fluoride removal from these solutions is proton-promoted and results in a strongly self-buffered suspensions at circumneutral pH, proceeds at a F : H consumption ratio of 2 : 1, and with recorded losses of up to 17 mM fluoride (58 F nm(-2)). These loadings exceed crystallographic site densities by a factor of 3-4, yet the reactions have no resolvable impact on particle size, shape and mineralogy. X-ray photoelectron spectroscopy (XPS) of frozen (-155 degrees C) wet mineral pastes revealed coexisting surface F- and HF0 species. Electron energy loss features pointed to multilayer distribution of these species at the mineral/water interface. XPS also uncovered a distinct form of Na+ involved in binding fluoride-bearing species. XPS and solid state magic angle spinning F-19 nuclear magnetic resonance measurements showed that these fluoride species were highly comparable to a sodium-bifluoride (NaHF2) reference. First layer surface species are represented as =Al-F-H-F-Al= and =Al-F-Na-F-Al=, and may form multi-layered species into the mineral/water interface. These results consequently point to a potentially overlooked inorganic fluorine species in a technologically relevant mineral/water interfacial systems.
36.	Skvarla, Jiri, et al. (författare) Accumulation of counterions and coions evaluated by cryogenic XPS as a new tool for describing the structure of electric double layer at the silica/water interface 2017 Ingår i: Physical Chemistry, Chemical Physics - PCCP. - Cambridge : The Royal Society of Chemistry. - 1463-9076 .- 1463-9084. ; 19:43, s. 29047-29052 Tidskriftsartikel (refereegranskat)abstract We introduce a new method of evaluating the structure of electric double layer (EDL) at the native solid/liquid interface using cryogenic X-ray photoelectron spectroscopy technique. This method is based on evaluating the atomic concentration ratio of counterions and co-ions of supporting electrolyte at the close-to-in situ state surface of colloid particles by the cryo-XPS and comparing it with analogous ratio predicted by EDL models. For silica colloids in aqueous KCl solutions at pH 6 to 8 it has been found that the latter ratio is higher than unity, as expected for the negatively charged surface of silica, but does not correspond with the prediction of the basic Gouy-Chapman EDL model for the ideal interface. However, it agrees with that deduced from experiments on electrolytic coagulation kinetics of analogous silica colloids by applying a simple EDL model of swellable ion-permeable (Donnanian) polyelectrolyte gel layer. It turns out that the traditional Stern layer-based concept of EDL at solid/liquid interfaces is not justified for metal oxides at least in KCl solutions.
37.	Sterchele, Stefano, et al. (författare) Influence of Metal Precursors and Reduction Protocols on the Chloride-Free Preparation of Catalysts for the Direct Synthesis of Hydrogen Peroxide without Selectivity Enhancers 2016 Ingår i: ChemCatChem. - : John Wiley & Sons. - 1867-3880 .- 1867-3899. ; 8:8, s. 1564-1574 Tidskriftsartikel (refereegranskat)abstract Different metal precursors and reducing agents were applied in the preparation of 1 wt % Pd catalysts supported on commercial ion-exchange resin (Lewatit K2621) and used in the direct synthesis of H2O2. The catalysts were characterized by using TEM and their performance was evaluated in the direct synthesis of H2O2 (in a batch and semi-batch reactor) to investigate the relationship between the catalyst preparation methods, morphology, and catalytic performance. As expected, both the choice of the Pd precursor and the reduction conditions had a strong influence on the size and size distribution of the resulting supported nanostructured metal nanoparticles and, consequently, on the catalytic performance. The best combination of metal precursor and reduction agent was [Pd(NH3)4]SO4 reduced with hydrogen. This catalyst had the largest average size of the Pd nanoparticles and the broadest size distribution.
38.	Sterchele, Stefano, et al. (författare) The effect of the metal precursor-reduction with hydrogen on a library of bimetallic Pd-Au and Pd-Pt catalysts for the direct synthesis of H2O2 2015 Ingår i: Catalysis Today. - : Elsevier. - 0920-5861 .- 1873-4308. ; 248, s. 40-47 Tidskriftsartikel (refereegranskat)abstract Two sets of bimetallic Pd-Pt (Pd: 1.0; Pt: 0.25-1.0%, w/w) and Pd-Au (Pd: 1.0; Au: 0.25-1.0%, w/w) catalysts have been used, with no added promoter, in the catalytic direct synthesis (CDS) of hydrogen peroxide from its elements at 2 °C with a CO2/O2/H2 mixture (72/25.5/2.5%, respectively). The catalysts were supported on the commercial macroreticular ion-exchange resin Lewatit K2621 and were obtained from the reduction with H2 of ion-exchanged cationic precursors at 5 bar and at 60 °C. The addition of Pt or Au to Pd produced an increase of the initial overall catalytic activity in comparison with monometallic Pd with both the second metals, but with Pt the increase was much higher than with Au. Moreover, the addition of 0.25% (w/w) Pt, or more, invariably made all the Pd-Pt catalysts less selective with respect to Pd alone. In the case of Au, by contrast, the addition of 0.25% w/w produced an increase, albeit small, of the selectivity. As the result, the most active and productive Pd-Pt catalyst was 1Pd025PtK2621 with 1891 mol(H2) mo l(Pd + Pt) - 1 h- 1 initially consumed, 1875 mol(H2 O2) mo l(Pd + Pt) - 1 h- 1 initially produced, a 45% selectivity towards H2O2 at 50% conversion of H2. In the case of the Pd-Au bimetallic catalysts, 1Pd025AuK2621 was the best one, with 1184 mol(H2) mo l(Pd + Pt) - 1 h- 1 initially consumed, 739 mol(H2 O2) mo l(Pd + Pt) - 1 h- 1 initially produced, a 55% selectivity towards H2O2 at 50% conversion of H2. Although the characterization of the Pd-Pt and Pd-Au catalysts with TEM showed that the morphology of the nanostructured metal phases in the Pd-Pt and Pd-Au catalysts was very different from each family to the other, no clear correlation between the size of the nanoparticles and their distribution and the catalytic performance was apparent. These catalysts were also generally different, especially the Pd-Au ones, from previously reported related materials obtained from the same support and the same precursor, but with a different reducing agent (formaldehyde). © 2014 Elsevier B.V. All rights reserved.
39.	Taheri, Masoud, et al. (författare) Cross-linked chitosan with a dicationic ionic liquid as a recyclable biopolymer-supported catalyst for cycloaddition of carbon dioxide with epoxides into cyclic carbonates 2018 Ingår i: New Journal of Chemistry. - : Royal Society of Chemistry. - 1144-0546 .- 1369-9261. ; 42:1, s. 587-597 Tidskriftsartikel (refereegranskat)abstract Development of eco-friendly, desirable and reusable catalysts particularly for reactions in regard to carbon dioxide fixation is still attractive in academic and industrial sectors. In this study, a dicationic ionic liquid was anchored to a cheap biopolymer, i.e., chitosan and the prepared hybrid composite was used in the cycloaddition reaction of CO2 with various epoxides for preparing five-membered cyclic carbonates under solvent-free conditions in high yield and selectivity without the addition any metal co-catalyst. The catalyst was characterized by 1H and 13C NMR, FTIR, UV-vis, XPS, TG, FESEM, and BET techniques. The catalyst was recovered and recycled at least five times without losing its activity and selectivity. Moreover, it has been demonstrated that chitosan through hydrogen bonding, coordination of amine groups with CO2 and also loosely bonded bromide ion to imidazolium ion have synergistic effects on the yield and selectivity of cyclic carbonates under optimum conditions. On the basis of the obtained results, a feasible mechanism was proposed for the reaction.
40.	Taheri, Masoud, et al. (författare) Organic–inorganic hybrid of anchored dicationic ionic liquid on Al-MCM-41-phosphovanadomolybdate toward selective oxidation of benzene to phenol 2019 Ingår i: Applied organometallic chemistry. - : John Wiley & Sons. - 0268-2605 .- 1099-0739. ; 33:8 Tidskriftsartikel (refereegranskat)abstract A phosphovanadomolybdate hybridized with an anchored dicationic ionic liquid on Al-MCM-41 was prepared through the anion exchange and characterized by 1H and 13C NMR, FTIR, UV?Vis, XRD, XPS, TGA, TEM, FESEM, ICP-OES and BET techniques. The obtained data demonstrated that the composite is a porous material with the high surface area and also having a large pore volume which are 405 m2 g?1 and 0.616 cm3 g?1 respectively. The prepared composite has shown an acceptable catalytic activity for converting benzene selectively to phenol with hydrogen peroxide as eco-friendly oxidant. Under the optimized reaction conditions, the hybrid catalyst resulted in phenol yield of 14.8% with 100% selectivity and a TOF value of 20.0 h?1. The catalyst also revealed a desired recovery and reusability. The efficient performance of the composite is related to the textural and polyoxometalate properties.
41.	Trubetskaya, Anna, et al. (författare) Potassium and soot interaction in fast biomass pyrolysis at high temperatures 2018 Konferensbidrag (refereegranskat)
42.	Trubetskaya, Anna, 1984-, et al. (författare) Potassium and soot interaction in fast biomass pyrolysis at high temperatures 2018 Ingår i: Fuel. - : Elsevier. - 0016-2361 .- 1873-7153. ; 225, s. 89-94 Tidskriftsartikel (refereegranskat)abstract This study aims to investigate the interaction between potassium and carbonaceous matrix of soot produced from wood and herbaceous biomass pyrolysis at high heating rates at 1250°C in a drop tube reactor. The influence of soot carbon chemistry and potassium content in the original biomass on the CO2 reactivity was studied by thermogravimetric analysis. The XPS results showed that potassium incorporation with oxygen-containing surface groups in the soot matrix did not occur during high temperature pyrolysis. The potassium was mostly found as water-soluble salts such as KCl, KOH, KHCO3 and K2CO3 in herbaceous biomass soot. The low ash-containing pinewood soot was less reactive than the potassium rich herbaceous biomass soot, indicating a dominating role of potassium on the soot reactivity. However, the catalytic effect of potassium on the reactivity remained the same after a certain potassium amount was incorporated in the soot matrix during pyrolysis. Raman spectroscopy results showed that the carbon chemistry of biomass soot also affected the CO2 reactivity. The less reactive pinewood soot was more graphitic than herbaceous biomass soot samples with the disordered carbon structure.
43.	Yu, Changxun, 1983-, et al. (författare) A cryogenic XPS study of Ce fixation on nanosized manganite and vernadite: Interfacial reactions and effects of fulvic acid complexation 2018 Ingår i: Chemical Geology. - : Elsevier BV. - 0009-2541 .- 1872-6836. ; 483, s. 304-311 Tidskriftsartikel (refereegranskat)abstract This study investigated interfacial reactions between aqueous Ce(III) and two synthetic nanosized Mn (hydr-) oxides (manganite: gamma-MnOOH, and vernadite: delta-MnO2) in the absence and presence of Nordic Lake fulvic acid (NLFA) at circumneutral pH by batch experiments and cryogenic X-ray photoelectron spectroscopy (XPS). The surfaces of manganite and vernadite were negatively charged (XPS-derived loadings of (Na+ K)/Cl > 1) and loaded with 0.42-4.33 Ce ions nm(-2). Manganite stabilized Ce-oxidation states almost identical to those for vernadite (approximately 75% Ce(IV) and 25% Ce(III)), providing the first experimental evidence that also a Mn (III) phase (manganite) can act as an important scavenger for Ce(IV) and thus, contribute to the decoupling of Ce from its neighboring rare earth elements and the development of Ce anomaly. In contrast, when exposed to Ce (III)-NLFA complexes, the oxidation of Ce by these two Mn (hydr-) oxides was strongly suppressed, suggesting that the formation of Ce(III) complexes with fulvic acid can stabilize Ce(III) even in the presence of oxidative Mn-oxide surfaces. The experiments also showed that Ce(III) complexed with excess NLFA was nearly completely removed, pointing to a strong preferential sorption of Ce(III)-complexed NLFA over free NLFA. This finding suggests that the Ce(III)-NLFA complexes were most likely sorbed by their cation side, i.e. Ce(III) bridging between oxide groups on the Mn (hydr-) oxides and negatively-charged functional groups in NLFA. Hence, Ce(III) was in direct contact with the oxidative manganite and vernadite but despite that not oxidized. An implication is that in organic-rich environments there may be an absence of Ce(IV) and Ce anomaly despite otherwise favorable conditions for Ce(III) oxidation.

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