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Thiago Sousa, Thales Fernando Damasceno Fernandes, Matheus J S Matos, Eduardo Nery Duarte Araujo, Mario S C Mazzoni, Bernardo R A Neves, Flávio Plentz
The association of organic molecules with 2D materials, creating hybrid systems with mutual influences, constitutes an important testbed for both basic science self-assembly studies and perspective applications. Following this concept, in this work, we show a rich phenomenology that is involved in the interaction of thionine with graphene, leading to a hybrid material formed by well-organized self-assembled structures atop graphene. This composite system is investigated by atomic force microscopy, electric transport measurements, and first principles calculations, which show: 1) an interesting time evolution of thionine self-assembled structures atop graphene; 2) the final molecular assembly is highly oriented (in accordance with the underlying graphene surface symmetry); and 3) thionine introduces a strong n-type doping effect in graphene...
May 24, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Ruiyun Huang, Christopher J Kucharczyk, Yangang Liang, Xiaohang Zhang, Ichiro Takeuchi, Sossina M Haile
An approach for measuring conductivity of thin-film electrolytes in an out-of-plane configuration, amenable to high-throughput experimentation, is presented. A comprehensive analysis of the geometric requirements for success is performed. Using samaria-doped ceria (Ce0.8Sm0.2O1.9, SDC) excellent agreement between bulk samples and thin films with continuous and patterned electrodes, 100-500 m in diameter, is demonstrated. Films were deposited on conductive Nb-doped SrTiO3, and conductivity measured by A.C...
May 24, 2018: ACS Combinatorial Science
Tianyi Zhang, Feifei Zhao, Li Li, Bin Qi, Dongxia Zhu, Jianhua Lü, Changli Lü
The past few years have witnessed the rapid development of carbon dots (CDs) due to their outstanding optical properties and a wide range of applications. However, the design and control of CDs with long-wavelength and multicolor emission are still huge challenges to be addressed for their practical use in different fields. Here, novel nitrogen doped multiple-cores@shell structured CDs with tricolor emissions of red, green and blue were constructed via one pot hydrothermal method from citric acid (CA) and 5-amino-1,10-phenanthroline (Aphen) as reactants and the growth process of CDs was monitored with the reaction time in the synthetic system...
May 24, 2018: ACS Applied Materials & Interfaces
Pengfei Li, Wei Zhang, Dongdong Li, Changhao Liang, Xiao Cheng Zeng
The most stable structures of two-dimensional (2D) GexPy and GexAsy monolayers with different stoichiometry (e.g., GeP, GeP2, GeP3) are explored systematically through the combination of the particle-swarm optimization (PSO) technique and density functional theory optimization. For GeP3, we show that the newly predicted most stable C2/m structure is 0.16 eV/atom lower in energy than the state-of-the-art P-3m1 structure reported previously (Nano Lett.2017, 17, 1833). The computed electronic band structures suggest that all the stable and metastable monolayers of GexPy are semiconductors with highly tunable bandgaps under the biaxial strain, allowing strain engineering of their bandgaps within nearly the whole visible-light range...
May 24, 2018: ACS Applied Materials & Interfaces
Zhe Zhao, Siliang Liu, Jixin Zhu, Jingsan Xu, Le Li, Zhaoqi Huang, Chao Zhang, Tianxi Liu
Interconnected close-packed nitrogen-doped porous carbon polyhedrons (NCPs) confined in a two-dimensional carbon nanosheets (CNSs) have been prepared through a sustainable one-pot pyrolysis of a simple solid mixture of zeolitic imidazolate framework-8 (ZIF-8) crystals and organic potassium as the precursors. The hierarchically organized framework of the NCP-CNS composites enables NCPs and CNSs acting as well-defined electrolyte reservoirs and mechanical buffers accommodating large volume expansions of NCPs, respectively...
May 24, 2018: ACS Applied Materials & Interfaces
C J C Smyth, S Mirkhanov, A H Quarterman, K G Wilcox
We report a solar pumped solid state laser using a 20 mm long, 3 mm diameter neodymium-doped yttrium aluminum garnet laser rod. This rod was placed in a liquid cooling chamber using a water-white-emulsion-paint mix. This mix provides cooling for the laser crystal and also doubles as a diffuse light scattering liquid. This enhances sunlight scattering and leads to a greater absorption in the laser rod. We numerically model the solar absorption in the laser rod using a ray-tracing model and predict a 2.6 times enhancement in absorption when a 98% reflective diffuse scatter is modelled compared to 0% scattering...
May 20, 2018: Applied Optics
Hirotaka Ono, Makoto Yamada
This paper investigates the applicability of a model of a cladding-pumped multicore erbium-doped fiber amplifier (CP-MC-EDFA) that employs the average inversion level of an erbium ion. The model is modified to include the effects of multiple cores for modifications of the background loss coefficient of the pump light. The model is validated experimentally by measurements of the pump power, gain transient, and intercore cross-gain modulation of a cladding-pumped 12-core EDFA in which the pump light is uniformly distributed in the inner cladding...
May 10, 2018: Applied Optics
Jumpei Ueda, Shun Miyano, Setsuhisa Tanabe
The Y3 Al2 Ga3 O12 :Ce3+ -Cr3+ compound is one of the brightest persistent phosphors, but its persistent luminescence (PersL) duration is not so long due to the relatively shallow Cr3+ electron trap. Comparing the vacuum referred binding energy of the electron trapping state by Cr3+ and those by lanthanide ions, we selected Yb3+ as a deeper electron trapping center. The Y3 Al2 Ga3 O12 :Ce3+ -Yb3+ phosphors show Ce3+ :5d→4f green persistent luminescence after ceasing blue light excitation. The formation of Yb2+ was confirmed by the increased intensity of absorption at 585 nm during the charging process...
May 23, 2018: ACS Applied Materials & Interfaces
Yifan Lin, Hao Wan, Fashen Chen, Xiaohe Liu, Renzhi Ma, Takayoshi Sasaki
Bottom-up synthesis is a promising method to design and control the morphology of metal-organic frameworks (MOFs). Here, square shaped two-dimensional (2D) MOF nanoplatelets with a thickness of ∼80 nm and a lateral dimension of 4-6 μm were successfully synthesized through a facile solvothermal treatment of Cu(NO3)2 and 4,4'-bipyridine in the presence of polyvinyl pyrrolidone (PVP). The growth of a cross-weaved structure assembled via 1D chains linked with 4,4'-bipyridine along the layer stacking direction was hindered by PVP, resulting in a high-aspect ratio of the nanoplatelets...
May 23, 2018: Dalton Transactions: An International Journal of Inorganic Chemistry
Monica Elisabet Graf, Solange Di Napoli, Maria Andrea Andrea Barral, Leila Saleh Medina, R Martín Negri, Marcelo Sepliarsky, Ana María Llois
In this work we study, by means of <i>ab initio</i> calculations, the structural, electronic and magnetic properties of Y-doped BiFeO<sub>3</sub> compounds. We determine that there is a morphotropic phase boundary at an yttrium concentration of (18 ± 2)%, where the structure changes from <i>R3c</i> to <i>Pnma</i>. This structural transition is driven by the chemical pressure induced by the dopant...
May 23, 2018: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Fang Wu, Hao Wang, Jiayuan Shi, Zongkai Yan, Shipai Song, Bangheng Peng, Xiaokun Zhang, Yong Xiang
Due to its high specific capacity, silicon is considered as a promising anode materials for LIBs. While, the synthesis strategies for those previous silicon-based anode materials with delicate hierarchically-structure are complicated or hazardous. Here, prussian blue analogues (PBAs), as widely used in ink, is deposited on the silicon nanoparticles surface (PBAs@Si-450) to modify silicon nanoparticles with a transition metal atoms and N doped carbon layer. A facile and green synthesis procedure of PBAs@Si-450 nanocomposites are precipitated in a co-precipitation process combined with a thermal treatment process at 450 oC...
May 23, 2018: ACS Applied Materials & Interfaces
Zhenhua Gao, Wei Zhang, Yongli Yan, Jun Yi, Haiyun Dong, Kang Wang, Jiannian Yao, Yong Sheng Zhao
Microscale laser switches have been playing irreplaceable roles in the development of photonic devices with high integration levels. However, it remains a challenge to switch the lasing wavelengths across a wide range due to relatively fixed energy bands in traditional semiconductors. Here, we report a strategy to switch the lasing wavelengths among multiple states based on proton-controlled intramolecular charge-transfer (ICT) process in organic dye-doped flexible microsphere resonant cavities. The protonic acids can effectively bind onto the ICT molecules, which thus enhance the ICT strength of the dyes, and lead to a red-shifted gain behaviors...
May 23, 2018: ACS Nano
Bing Xu, Dongyu Li, Zhen Huang, Chunliang Tang, Wenhao Mo, Ying Ma
Luminescence concentration quenching, mainly due to a cross relaxation (CR) process between lanthanide ions (Ln3+), widely occurs in Ln3+ doped luminescent materials, setting a limit in the dopant content of Ln3+ emitters to withhold the brightness. Here, we introduced Na+ ions into the CaF2 host lattice codoped with Nd3+ emitters that alleviates concentration quenching greatly. And we show that the optimal dopant concentration of Nd3+ in colloidal CaF2:Nd nanoparticles increased from 10 to 30 mol%, resulting in an ∼32 times near-infrared (NIR) (1052 nm) brightness under 800 nm laser irradiation...
May 23, 2018: Dalton Transactions: An International Journal of Inorganic Chemistry
Anthony Fiorino, Dakotah Thompson, Linxiao Zhu, Rohith Mittapally, Svend-Age Biehs, Odile Bezencenet, Nadia El-Bondry, Shailendra Bansropun, Philippe Ben-Abdallah, Edgar Meyhofer, Pramod Reddy
In this work we demonstrate thermal rectification at the nanoscale between doped Si and VO2 surfaces. Specifically, we show that the metal-insulator transition of VO2 makes it possible to achieve large differences in the heat flow between Si and VO2 when the direction of the temperature gradient is reversed. We further show that this rectification increases at nanoscale separations, with a maximum rectification coefficient exceeding 50% at ∼140 nm gaps and a temperature difference of 70 K. Our modeling indicates that this high rectification coefficient arises due to broadband enhancement of heat transfer between metallic VO2 and doped Si surfaces, as compared to narrower-band exchange that occurs when VO2 is in its insulating state...
May 23, 2018: ACS Nano
Tony Garnier, Mathieu Danel, Valentin Magne, Anthony Pujol, Valérie Beneteau, Patrick Pale, Stefan Chassaing
The copper(I)-doped zeolite CuI-USY proved to be a versatile, efficient, and recyclable catalyst for various Ullmann-type coupling reactions. Easy-to-prepare and cheap, this catalytic material enables the arylation and heteroarylation of diverse O-, N-, S- and C-nucleophiles under ligand-free conditions, while exhibiting large functional group compatibility. The facility of this catalyst to promote C-O bond formation was further demonstrated with the total synthesis of 3-methylobovatol, a naturally occurring diaryl ether of biological relevance...
May 23, 2018: Journal of Organic Chemistry
Shuliang Yang, Yanan Zhu, Changyan Cao, Li Peng, Wendy L Queen, Weiguo Song
The synthesis of porous carbon spheres with hierarchical porous structures coupled with the doping of heteroatoms is particularly important for advanced applications. In this research, a new route for efficient and controllable synthesis of hierarchical porous carbon spheres co-doped with nitrogen, phosphorus, and sulfur (denoted as NPS-HPCs) was reported. This new approach combines in situ polymerization of hexachlorocyclophosphazene and 4, 4'-sulfonyldiphenol with the self-assembly of colloidal silica nanoparticles (SiO2 NPs)...
May 23, 2018: ACS Applied Materials & Interfaces
Anny Leudjo Taka, Elvis Fosso-Kankeu, Kriveshini Pillay, Xavier Yangkou Mbianda
In this study, an insoluble nanosponge biopolymer composite was synthesized, using a combined process of amidation reaction, cross-linking polymerization, and sol-gel method to obtain a phosphorylated multiwalled carbon nanotube-cyclodextrin/silver-doped titania (pMWCNT-βCD/TiO2 -Ag). This work mainly emphasized on the removal of lead (Pb2+ ) and cobalt (Co2+ ) metal ions from synthetic and real wastewater samples using the synthesized pMWCNT-βCD/TiO2 -Ag as a biosorbent. The new material was characterized by Fourier transform infrared (FTIR) spectroscopy, zeta potential, Brunauer-Emmett-Teller (BET) method, and scanning electron microscopy (SEM)...
May 23, 2018: Environmental Science and Pollution Research International
Yuan Cheng, Kangning Sun
Yb3+ -Tm3+ co-doped up-conversion powder phosphors using Zn(Alx Ga1-x )2 O4 (ZAGO) as the host materials were synthesized via solid-state reaction successfully. In addition, the morphology, structural characterization and up-conversion luminescent properties were all investigated by scanning electron microscope (SEM), x-ray diffraction (XRD) and fluorescence spectrophotometer (F-7000), respectively. Under the excitation of a 980 nm laser, all as-prepared powders can carry out blue emission at about 477 nm (corresponding to 1 G4  → 3 H6 transition of Tm3+ ions), and red emission at about 691 nm (attributed to 3 F3  → 3 H6 transition of Tm3+ ions)...
May 22, 2018: Journal of Fluorescence
Jianguang Feng, Hongzhou Dong, Beili Pang, Feifei Shao, ChunKai Zhang, Liyan Yu, Lifeng Dong
The effects of four heteroatoms (B, N, P, and S) with three doping patterns on graphene quantum dots (GQDs) are systematically investigated using time-dependent density functional theory (TD-DFT). The absorption spectra and HOMO-LUMO gaps are quantitatively analyzed to study the correlations between the optical properties and heteroatom doping of doped GQDs. Heteroatom doping can endow GQDs with various new optical and structural properties, depending on the dopants and doping configurations. Compared with the absorption spectra of pristine GQD, both N and S surface doping demonstrate a slight blue shift, whereas B and P doping lead to a blue shift for edge-doped GQDs with heteroatoms in a pentatomic ring...
May 23, 2018: Physical Chemistry Chemical Physics: PCCP
Libin Yang, Qinqin Sang, Juan Du, Ming Yang, Xiuling Li, Yu Shen, Xiaoxia Han, Xin Jiang, Bing Zhao
Ag simultaneously deposited and doped TiO2 (Ag-TiO2) hybrid nanoparticles (NPs) were prepared via a sol-hydrothermal method, as both a sensitive surface-enhanced Raman scattering (SERS) substrate and a superior photocatalyst for the first time. Ag-TiO2 hybrid NPs exhibit excellent SERS performance for several probe molecules and the enhancement factor is calculated to be 1.86 × 105. The detection limit of the 4-mercaptobenzoic acid (4-MBA) probe on the Ag-TiO2 substrate is 1 × 10-9 mol L-1, which is four orders of magnitude lower than that on pure TiO2 as a consequence of the synergistic effects of TiO2 and Ag...
May 23, 2018: Physical Chemistry Chemical Physics: PCCP
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