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Nanocrystalline powders of monometallic and bimetallic imidazolates of Co, Zn and Ag were produced by a reaction carried out in water. The powders were characterized by powder X-ray diffraction and the crystal structures of the new compounds Ag2ZnIm4 and Ag2CoIm4 (Im = imidazolate) were solved. Heterometallic Co/Zn imidazolates showed the known Zn-zni crystal structure while Ag/Zn and Ag/Co systems were isostructural to the copper analogs. The powders were further characterized by EDX, UV-Vis and FTIR ATR spectroscopy in the solid state. The catalytic experiments indicated that out of the studied heterometallic compounds only Ag2Co(Im)4 exhibits some catalytic activity in the oxidation reaction of 1-phenylethanol with tert-butylhydroperoxide at elevated temperatures. [ABSTRACT FROM AUTHOR]

In recent years, the growing interest in applying photoelectrocatalysis (PEC) to decompose organic pollutants has resulted in the need to search for new photoelectrode materials with high activity under visible light radiation. The presented research showed an increased photoelectrocatalytic activity under sunlight of Ti/TiO2 sensitized with SnS quantum dots, obtained by the successive ionic layer adsorption and reaction (SILAR) method. The presence of SnS caused the enhanced absorption of visible irradiation and the reduction of recombination of generated charges by a p--n heterojunction created with the TiO2. The highest efficiency of photoelectrocatalytic degradation of anticancer drugs (ifosfamide, 5-fluorouracil, imatinib) was achieved for the SnS-Ti/TiO2 photoelectrode with a SnS quantum dot size from 4 to 10 nm. In addition, a decrease of IF PEC degradation efficiency was observed with increasing pH and with the presence of Cl-, NO3-, HCO3- and organic matter in the treated solution. Studies of the PEC mechanism have shown that drug degradation occurs mainly as a result of the direct and indirect action of photogenerated holes on the SnS-Ti/TiO2 photoelectrode, and the identified degradation products allowed for the presentation of the degradation pathway of IF, 5-FU and IMB. Duckweed (Lemna minor) growth inhibition tests showed no toxicity of the drug solutions after treatment. [ABSTRACT FROM AUTHOR]

We report on the phase formation and the superconducting properties in the NbS2 system. Specifically, we have performed a series of standardized solid-state syntheses in this system, which allow us to establish a comprehensive synthesis map for the formation of the two polytypes 2H-NbS2 and 3R-NbS2, respectively. We show that the identification of two polytypes by means of X-ray diffraction is not always unambiguous. Our physical property measurements on a phase-pure sample of 3R-NbS2, on a phase-pure sample of 2H-NbS2, and a mixed phase sample confirm earlier reports that 2H-NbS2 is a bulk superconductor and that 3R-NbS2 is not a superconductor above T = 1.75 K. Our results clearly show that specific heat measurements, as true bulk measurements, are crucial for the identification of superconducting materials in this and related systems. Our results indicate that for the investigation of van der Waals materials great care has to be taken on choosing the synthesis conditions for obtaining phase pure samples. [ABSTRACT FROM AUTHOR]

Novel visible light responsive materials for water splitting are essential for the efficient conversion of solar energy into hydrogen bond energy. Among other semiconductors, gadolinium orthovanadate has appropriate conduction and valence band edges positioned to split water molecules and a narrow band gap that allows the use of visible light for hydrogen generation. Thus, we present here that hydrogen evolution under visible light (λ ＞ 420 nm) could be accomplished using hierarchical 3D GdVO4 particles, obtained by a simple, one pot hydrothermal synthesis. We found that applying various reaction components, such as EDTA-Na2 and EDTA, and adjusting the pH of the solution allow one to tune the shape of GdVO4 (such as short nanowires, long nanowires, short nanorods, long nanorods, nanoparticles and spheres – all having a tetragonal crystal structure) as well as optical and photocatalytic properties. The highest ability to photocatalytically split methanol solution into hydrogen under UV-Vis irradiation was detected for the long nanowire sample (42 μmol h−1), having almost 11 times higher efficiency in comparison with the weakest sample – short nanowires. In addition, GdVO4 spheres generated H2 more than 2 times (5.75 μmol h−1) in comparison with the short nanorod sample (2.5 μmol h−1) under visible light excitation. Photostable in three-hour work cycles, long nanowires and spheres were even able to generate hydrogen from pure water, reaching values of 17 and 3 μmol under UV-Vis and Vis light, respectively. [ABSTRACT FROM AUTHOR]

Previously unreported σ-phases in the ternary niobium-based systems Nb–X–Ga for X = Ru, Rh, Pd, Ir, Pt, Au, and Nb–X–Al for X = Ir, and Pt are presented, prepared by arc-melting followed by annealing at 1000 °C for 1 week. The phases are primitive tetragonal (P42/mnm, no. 136) with lattice parameters of a = 9.8336(2)–9.9432(1) Å and c = 5.1098(1)–5.1718(1) Å. Refinements of the single crystal X-ray diffraction data for the Ru and Ir containing materials gave the formulas Nb20Ru5Ga5 and Nb20Ir4Ga6, showing mixing of X/Ga on the crystallographic 8i2 and 2a sites of the structure, a type of disorder frequently found in σ-phases. We present a graphical classification for ternary σ-phases that places our materials in context with previous materials. The materials do not show evidence of bulk superconductivity above 2 K. Synthesis of equivalent Ta-based σ-phases was attempted but they were not found. [ABSTRACT FROM AUTHOR]

Following the predictions of total energy calculations, a tetragonal SrMn2P2 phase is proposed and successfully formed under high pressure. At ambient pressure, SrMn2P2 adopts the primitive trigonal La2O3 structure type (space group P3̅m1). However, the results of total energy calculations indicate that SrMn2P2 should be more stable in the tetragonal ThCr2Si2 structure type (space group I4/mmm) than in its known trigonal structure, thus motivating our synthetic experiments. Guided by these calculations, a new tetragonal polymorph of SrMn2P2 was found under the relatively mild conditions of 5 GPa applied pressure at a temperature of 900 °C through the transformation of the ambient pressure trigonal form. The new polymorph has the body centered tetragonal ThCr2Si2 structure type, as predicted. The electronic structure calculations indicate the likelihood of antiferromagnetic, semiconducting properties for the high pressure SrMn2P2 phase. [ABSTRACT FROM AUTHOR]