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Christopher A Hosier, Christopher J Ackerson
Ligand exchange is a fundamental reaction of metal nanoparticles. Multiple symmetry and kinetic exchange environments are observed for thiol protected gold nanoparticles, but the correlation between these is unclear. Structural study of ligand exchange on chalcogenide passivated gold clusters has so far revealed the locations of 10% or fewer of incoming ligands. In a set of 13 crystal structures, we reveal the locations of up to 17 ligands of the 18 ligands in thiolate for selenolate exchanged Au25SeR18-xSRx clusters...
December 11, 2018: Journal of the American Chemical Society
R Holomb, O Kondrat, V Mitsa, M Veres, A Czitrovszky, A Feher, N Tsud, M Vondráček, K Veltruská, V Matolín, K C Prince
The super-bandgap laser irradiation of the in situ prepared As-S chalcogenide films was found to cause drastic structural transformations and unexpected selective diffusion processes, leading to As enrichment on the nanolayer surface. Excitation energy dependent synchrotron radiation photoelectron spectroscopy showed complete reversibility of the molecular transformations and selective laser-driven mass transport during "laser irradiation"-"thermal annealing" cycles. Molecular modeling and density functional theory calculations performed on As-rich cage-like clusters built from basic structural units indicate that the underlying microscopic mechanism of laser induced transformations is connected with the realgar-pararealgar transition in the As-S structure...
December 7, 2018: Journal of Chemical Physics
James A Clark, Anna Murray, Jung-Min Lee, Tom S Autrey, Andrew D Collord, Hugh W Hillhouse
Molecular inks based on dimethyl sulfoxide, thiourea, and metal salts have been used to form high optoelectronic quality semiconductors and have led to high power conversion efficiencies for solution-processed photovoltaic devices for Cu2ZnSn(S,Se)4 (CZTS), Cu2Zn(Ge,Sn)(S,Se)4 (CZGTS), CuIn(S,Se)2 (CIS) and Cu(In,Ga)(S,Se)2 (CIGS). However, several metal species of interest including Ag(I), In(III), Ge(II), and Ge(IV) have either low solubility (requiring dilute inks) or lead to precipitation or gelation. Here, we demonstrate that the combination of N,N-dimethylformamide (DMF) and thiourea (TU) has the remarkable ability to form intermediate-stability acid-base complexes with a wide number of metal chloride Lewis acids (CuCl, AgCl, ZnCl2, InCl3, GaCl3, SnCl4, GeCl4, and SeCl4) to form high-concentration stable molecular inks...
December 9, 2018: Journal of the American Chemical Society
Julie L Fenton, Benjamin C Steimle, Raymond E Schaak
For polymorphic solid-state systems containing multiple distinct crystal structures of the same composition, identifying rational pathways to selectively target one particular structure is an important synthetic capability. Cation exchange reactions can transform a growing library of metal chalcogenide nanocrystals into different phases by replacing the cation sublattice, often while retaining morphology and crystal structure. However, only a few examples have been demonstrated where multiple distinct phases in a polymorphic system could be selectively accessed using nanocrystal cation exchange reactions...
December 7, 2018: Inorganic Chemistry
Zheming Liu, Jun Liu, Yanbin Huang, Jing Li, Yi Yuan, Haihang Ye, Dongxu Zhu, Zhijie Wang, Aiwei Tang
Multinary copper-based chalcogenides exhibit significant performance in photocatalytic hydrogen evolution due to their suitable optical bandgap for visible light absorption and environmentally friendly character. Herein, high-quality wurtzite CuGaS2 (CGS) nanocrystals (NCs) were synthesized by using a one-step heating-up process without any injection, and the morphology could be tuned from one-dimensional (1D) to two-dimensional (2D) by precise choice of surface ligands and gallium precursors. The formation mechanism of CGS NCs was studied comprehensively by means of the temporal-evolution of the morphology, crystal structure and optical absorption results...
December 7, 2018: Nanoscale
Mônica Silveira Wagner, Eduarda Schultze, Thais Larre Oliveira, Priscila Marques Moura de Leon, Helena Strelow Thurow, Vinicius Farias Campos, Isabel Oliveira, Diego de Souza, Oscar Endrigo Dorneles Rodrigues, Tiago Collares, Fabiana Kömmling Seixas
Triple-negative breast cancer represents about 15% of all cases of breast cancer, and still represents a therapeutic challenge. 3'-Azido-3'-deoxythymidine (AZT) is a nucleoside reverse transcriptase inhibitor with antitumor activity. Chalcogenides compounds, such as selenium, are very important intermediates applied in organic synthesis. Our objective was to investigate the effect and the underlying cell death mechanisms of AZT and its derivatives, in human breast cancer cell lines. The inhibitory effect of AZT and derivatives (1072, 1073, and 1079) was determined by MTT assay (0...
2018: Frontiers in Oncology
Tiening Jin, Junchao Zhou, Hao-Yu Greg Lin, Pao Tai Lin
A mid-infrared (mid-IR) sensor chip was demonstrated for volatile organic compounds (VOCs) detection. The sensor con-sisted of As2Se3 optical waveguides built by microelectronic fabrication processes. The VOCs sensing performance was char-acterized by measuring acetone and ethanol vapors at their characteristic C-H absorption from λ = 3.40 to 3.50 µm. Continu-ous VOCs detection with < 5 s response time was achieved by measuring the intensity attenuation of the waveguide mode. The miniaturized non-invasive VOCs sensor can be applied to breath analysis and environmental toxin monitoring...
December 5, 2018: Analytical Chemistry
Yu-Jun Zheng, Yong-Fang Shi, Chong-Bin Tian, Hua Lin, Li-Ming Wu, Xin-Tao Wu, Qi-Long Zhu
Mixed-anion chalcohalides have attracted significant attention lately, attributable to their unique structure compositions and captivating physicochemical properties. Herein, an unprecedented pentanary chalcohalide, Cs2[Mn2Ga3S7Cl] (1), was discovered by solid-state reaction at 1223 K. It is constructed by alternately stacked layers, each of which is made by a 2D [Ga3S9]9- ribbon embedded with 1D [Mn2S8Cl]13- chains. The coexistence of two Mn-coordinated polyhedra ([MnS6] octahedra and hetero-ligand [MnS3Cl] tetrahedra) in one material is surprisingly observed for the first time in the Mn-containing inorganic chalcogenides or chalcohalides...
December 4, 2018: Chemical Communications: Chem Comm
Ke Fan, Haiyuan Zou, Yue Lu, Hong Chen, Fusheng Li, Jinxuan Liu, Licheng Sun, Lianpeng Tong, Michael F Toney, Manling Sui, Jiaguo Yu
As one of the most remarkable oxygen evolution reaction (OER) electrocatalysts, metal chalcogenides have been intensively reported due to their high OER activities during the past few decades. It has been reported that electron-chemical conversion of metal chalcogenides into oxides/hydroxides would take place after OER. However, the transition mechanism of such unstable structures, as well as the real active sites and catalytic activity during OER for these electrocatalysts, has not been understood yet, which urgently needs a direct observation for the electrocatalytic water oxidation process, especially at nano or even angstrom scale...
December 3, 2018: ACS Nano
Qinghua Liang, Yun Zheng, Chengfeng Du, Yubo Luo, Jin Zhao, Hao Ren, Jianwei Xu, Qingyu Yan
The emerging sodium ion batteries (SIBs) are believed to be prospective substitutes of lithium ion batteries (LIBs) for the wide distribution of sodium resources. However, to compensate for the sluggish reaction kinetics and higher intrinsic potential of Na+ than Li+, cost-effective, reliable, and sustainable electrode materials are required to be urgently explored for practical applications. Herein, 2D ternary tin thiophosphate (SnP2S6) nanosheets (~10 nm thickness) grown on graphene (denoted as SPS/G hybrid) are demonstrated as intriguing anodes for SIBs...
December 3, 2018: ACS Nano
Desmond K Loke, Jonathan M Skelton, Tae Hoon Lee, Rong Zhao, Tow-Chong Chong, Stephen R Elliott
We describe how the crystallization kinetics of a suite of phase-change systems can be controlled by using a single-shot treatment via "initial crystallization" effects. Ultrarapid and highly stable phase-change structures (with excellent characteristics), viz. conventional and sub-10 nm sized cells (400 ps switching and 368 K for 10 year data retention), stackable cells (900 ps switching and 1 × 106 cycles for similar "switching-on" voltages), and multilevel configurations (800 ps switching and resistance-drift power-law coefficients <0...
December 3, 2018: ACS Applied Materials & Interfaces
Mario Behrens, Andriy Lotnyk, Jürgen W Gerlach, Isom Hilmi, Tobias Abel, Pierre Lorenz, Bernd Rauschenbach
Two-dimensional van-der-Waals-bonded chalcogenide heterostructures have recently received a lot of attention due to promising applications in the fields of photonics, plasmonics and data storage. Of particular interest is the interfacial switching process inherent in these structures, which is assumed to occur locally at the van-der-Waals interfaces and thus represents an intracrystalline transition. However, detailed experimental studies on the underlying mechanism are still lacking. In this work, epitaxially grown thin films consisting of van-der-Waals-bonded Ge-Sb-Te and GeTe/Sb2Te3 based heterostructures are employed as a model system to investigate structural changes induced by a single ns-laser pulse...
November 30, 2018: Nanoscale
Norbert Werner Mitzel, Josef Holub, Jindřich Fanfrlík, Drahomír Hnyk, Paul Lane, Derek Wann, Yury Vishnevskiy, Denis Tikhonov, Christian Reuter
Samples of closo-1,2-(EH)2-1,2-C2B10H10 (E = S, Se) have been prepared; in the case of E = Se for the first time. Their semi-experimental equilibrium molecular structures were established by the concerted use of quantum-chemical computations and gas elec¬tron diffraction (GED). A method has been developed and implemented to quantify the contribution of experimental data to each refined structural parameter. The accuracy of the experimental structures, as well as those computed at the MP2 level, were gauged by com¬parison of experimental 11B NMR chemical shifts with quantum-chemically computed ones; the inclusion of electron correlation (GIAO-MP2) provides superior results...
November 29, 2018: Chemistry: a European Journal
Baoping Zhang, Guanglin Xia, Wei Chen, Qinfen Gu, Dalin Sun, Xuebin Yu
Magnesium sulfide (MgS), representative of alkaline-earth metal chalcogenides (AEMCs), is a potential conversion/alloy-type electrode material for lithium ion batteries (LIBs), by virtue of its low potential voltage, high theoretical capacity and abundant magnesium resource. However, the limited capacity utilization and inferior rate performance still hinder its practical application, and the progress is rather slow due to the challenging fabrication technique for MgS. Herein, we report a series of controlled-size hollow MgS Nanocrystals (NCs) homogenously distributed on graphene (MgS@G), fabricated through a metal hydride framework (MHF) strategy, and its application as advanced electrode material for LIBs...
November 28, 2018: ACS Nano
Jack N Blandy, Shuai Liu, Catherine F Smura, Simon J Cassidy, Daniel N Woodruff, John E McGrady, Simon J Clarke
The structures of two new oxide chalcogenide phases, Sr2 CuO2 Cu2 S2 and Sr2 CuO2 Cu2 Se2 , are reported, both of which contain infinite CuO2 planes containing Cu2+ and which have Cu+ ions in the sulfide or selenide layers. Powder neutron diffraction measurements show that Sr2 CuO2 Cu2 Se2 exhibits long-range magnetic ordering with a magnetic structure based on antiferromagnetic interactions between nearest-neighbor Cu2+ ions, leading to a √2 a × √2 a × 2 c expansion of the nuclear cell. The ordered moment of 0...
November 27, 2018: Inorganic Chemistry
Kolleboyina Jayaramulu, Justus Masa, Dulce M Morales, Ondrej Tomanec, Vaclav Ranc, Martin Petr, Patrick Wilde, Yen-Ting Chen, Radek Zboril, Wolfgang Schuhmann, Roland A Fischer
2D layered materials, including metal-di-chalcogenides and transition metal layered double hydroxides, among others, are intensively studied because of new properties that emerge from their 2D confinement, which are attractive for advanced applications. Herein, 2D cobalt ion (Co2+ ) and benzimidazole (bIm) based zeolite-imidazole framework nanosheets, ZIF-9(III), are reported as exceptionally efficient electrocatalysts for the oxygen evolution reaction (OER). Specifically, liquid-phase ultrasonication is applied to exfoliate a [Co4 (bIm)16 ] zeolite-imidazole framework (ZIF), named as ZIF-9(III) phase, into nanoscale sheets...
November 2018: Advanced Science (Weinheim, Baden-Wurttemberg, Germany)
Yoon Seo Kim, Jaejung Song, Chihyun Hwang, Xuejing Wang, Haiyan Wang, Judith L MacManus-Driscoll, Hyun-Kon Song, Seungho Cho
Highly porous thin films and nanostructure arrays are created by a simple process of selective dissolution of a water-soluble material, Sr3 Al2 O6 . Heteroepitaxial nanocomposite films with self-separated phases of a target material and Sr3 Al2 O6 are first prepared by physical vapor deposition. NiO, ZnO, and Ni1- x Mg x O are used as the target materials. Only the Sr3 Al2 O6 phase in each nanocomposite film is selectively dissolved by dipping the film in water for 30 s at room temperature. This gentle and fast method minimizes damage to the remaining target materials and side reactions that can generate impurity phases...
November 2018: Advanced Science (Weinheim, Baden-Wurttemberg, Germany)
Kun Ren, Min Zhu, Wenxiong Song, Shilong Lv, Mengjiao Xia, Yong Wang, Yaoyao Lu, Zhenguo Ji, Zhitang Song
Germanium chalcogenides, especially GeSe and GeTe alloys, have recently gained popularity because of their Ovonic threshold (volatile) and memory (non-volatile) switching properties, with great potential for electric storage applications. Materials designed in a pseudo-binary way may possess superior properties in their phase transition, e.g. GeTe-Sb2Te3 materials, and bring about revolutionary advances in optical storage. However, to date, the electrical switching behaviors of films of pseudo-binary GeSe-GeTe have not yet been studied, and neither have the structural characteristics...
November 26, 2018: Nanoscale
Yun Xu, Jingbo Sun, Jesse Frantz, Mikhail I Shalaev, Wiktor Walasik, Apra Pandey, Jason D Myers, Robel Y Bekele, Alexander Tsukernik, Jasbinder S Sanghera, Natalia M Litchinitser
Ultra-compact, low-loss, fast, and reconfigurable optical components, enabling manipulation of light by light, could open numerous opportunities for controlling light on the nanoscale. Nanostructured all-dielectric metasurfaces have been shown to enable extensive control of amplitude and phase of light in the linear optical regime. Among other functionalities, they offer unique opportunities for shaping the wave front of light to introduce the orbital angular momentum (OAM) to a beam. Such structured light beams bring a new degree of freedom for applications ranging from spectroscopy and micromanipulation to classical and quantum optical communications...
November 12, 2018: Optics Express
Florent Starecki, Alain Braud, Nora Abdellaoui, Jean-Louis Doualan, Catherine Boussard-Plédel, Bruno Bureau, Patrice Camy, Virginie Nazabal
We report on the observation of the long wave-infrared (LWIR) emission centered at 7.3 µm of Sm3+ doped chalcogenide fibers. The chemical composition of the selenide glass host matrix (Ga5 Ge20 Sb10 Se65 ) enables the drawing of 500 ppm and 1000 ppm Sm3+ doped fibers. By means of conventional glass elaboration methods, these Sm3+ doped fibered materials exhibit a significant emission band from 6.5 to 8.5 µm with a maximum emission around 7.3 µm whether they are excited at 1.45 µm or at 2.05 µm. Absorption spectra, Judd-Ofelt analysis, NIR, MWIR and LWIR luminescence spectra are presented and discussed...
October 1, 2018: Optics Express
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