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Tongtao Li, Bin Xue, Biwei Wang, Guannan Guo, Dandan Han, Yancui Yan, Angang Dong
Self-assembled nanocrystal (NC) superlattices are emerging as an important class of materials with rationally modulated properties. Engineering the nanoscale structure of constituent building blocks as well as the mesoscale morphology of NC superlattices is a crucial step in widening their range of applications. Here, we report a template-assisted epitaxial assembly strategy, enabling growth of freestanding, carbon-coated tubular monolayer superlattices (TMSLs). Specifically, we design and construct TMSLs of hollow Mn3O4 NCs (h-Mn3O4-TMSLs) by exploiting structural evolution of MnO NCs...
August 28, 2017: Journal of the American Chemical Society
Quanbing Liu, Shan Ji, Juan Yang, Hui Wang, Bruno G Pollet, Rongfang Wang
An allomorph MnO₂@MnO₂ core-shell nanostructure was developed via a two-step aqueous reaction method. The data analysis of Scanning Electron Microscopy, Transmission Electron Microscopy, X-Ray Diffraction and N₂ adsorption-desorption isotherms experiments indicated that this unique architecture consisted of a porous layer of amorphous-MnO₂ nano-sheets which were well grown onto the surface of α-MnO₂ nano-needles. Cyclic voltammetry experiments revealed that the double-layer charging and Faradaic pseudo-capacity of the MnO₂@MnO₂ capacitor electrode contributed to a specific capacitance of 150...
August 24, 2017: Materials
Xiaoyan Jin, Joohyun Lim, Yoonhoo Ha, Nam Hee Kwon, Hyeyoung Shin, In Young Kim, Nam-Suk Lee, Myung Hwa Kim, Hyungjun Kim, Seong-Ju Hwang
The effect of the catalyst morphology on the growth of carbon nanotubes (CNT) on nanostructured transition metal oxides was investigated to study a novel low-temperature synthetic route to functional CNT-transition metal oxide nanocomposites. Among several nanostructured manganese oxides with various morphologies and structures, only exfoliated 2D nanosheets of layered MnO2 acted as an effective catalyst for the chemical vapor deposition of CNT at low temperatures of 400-500 °C, which emphasizes the critical role of the catalyst morphology in CNT growth...
August 31, 2017: Nanoscale
Priya Gopal, Riccardo De Gennaro, Marta Silva Dos Santos Guzmao, Rabih Al Rahal Al Orabi, Haihang Wang, Stefano Curtarolo, Marco Fornari, Marco Buongiorno Nardelli
We discuss the application of the Agapito Curtarolo and Buongiorno Nardelli (ACBN0) pseudo-hybrid Hubbard density functional to several transition metal oxides. ACBN0 is a fast, accurate and parameter-free alternative to traditional DFT+U and hybrid exact exchange methods. In ACBN0, the Hubbard energy of DFT+U is calculated via the direct evaluation of the local Coulomb and exchange integrals in which the screening of the bare Coulomb potential is accounted for by a renormalization of the density matrix. We demonstrate the success of the ACBN0 approach for the electronic properties of a series technologically relevant mono-oxides (MnO, CoO, NiO, FeO, both at equilibrium and under pressure)...
August 15, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
M Haris Mahyuddin, Yoshihito Shiota, Aleksandar Staykov, Kazunari Yoshizawa
While the most likely structure of the active site in iron-containing zeolites has been recently identified as [FeO](2+) (Snyder et al. Nature 2016, 536, 317-321), the mechanism for the direct conversion of methane to methanol over this active species is still debatable between the direct-radical-rebound or nonradical (concerted) mechanism. Using density functional theory on periodic systems, we calculated the two reaction mechanisms over two d(4) isoelectronic systems, [FeO](2+) and [MnO](+) zeolites. We found that [FeO](2+) zeolites favor the direct-radical-rebound mechanism with low CH4 activation energies, while [MnO](+) zeolites prefer the nonradical mechanism with higher CH4 activation energies...
August 15, 2017: Inorganic Chemistry
T Elovaara, J Tikkanen, S Granroth, S Majumdar, R Félix, H Huhtinen, P Paturi
We report the effect of photonic field on the electronic and magnetic structure of a low bandwidth manganite [Formula: see text] [Formula: see text]MnO3 (PCMO) thin film. In particular, the present study confirmed a mechanism that was recently proposed to explain how optical excitation can bias or directly activate the metamagnetic transition associated with the colossal magnetoresistance (CMR) effect of PCMO. The transition is characterized by a shift in the dynamic equilibrium between ferromagnetic (FM) and antiferromagnetic clusters, explaining how it can be suddenly triggered by a sufficient external magnetic field...
August 7, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Ji-Liang Niu, Gui-Xia Hao, Jia Lin, Xiao-Bin He, Palanivel Sathishkumar, Xiao-Ming Lin, Yue-Peng Cai
By application of newly designed ligand 5-(3-(pyridin-3-yl)benzamido)isophthalic acid (H2PBI) to react with Mn(NO3)2 under solvothermal conditions, a 2-fold interpenetrated Mn-based metal-organic framework (Mn-PBI) with rutile-type topology has been obtained. When treated as a precursor by pyrolysis of Mn-PBI at 500 °C, mesoporous MnO/C-N nanostructures were prepared and treated as an lithium-ion battery anode. The MnO/C-N manifests good capacity of approximately 1085 mAh g(-1) after 100 cycles together with superior cyclic stability and remarkable rate capacity, which is supposed to benefit from a large accessible specific area and unique nanostructures...
August 4, 2017: Inorganic Chemistry
Majid Ebrahimizadeh Abrishami, Marcel Risch, Julius Scholz, Vladimir Roddatis, Norbert Osterthun, Christian Jooss
An improved understanding of the correlation between the electronic properties of Mn-O bonds, activity and stability of electro-catalysts for the oxygen evolution reaction (OER) is of great importance for an improved catalyst design. Here, an in-depth study of the relation between lattice structure, electronic properties and catalyst performance of the perovskite Ca1-xPrxMnO₃ and the first-order RP-system Ca2-xPrxMnO₄ at doping levels of x = 0, 0.25 and 0.5 is presented. Lattice structure is determined by X-ray powder diffraction and Rietveld refinement...
November 14, 2016: Materials
Qiao Yang, Zhenxing Wu, Lifen Liu, Fengxiang Zhang, Shengna Liang
Conventional oil sewage treatment methods can achieve satisfactory removal efficiency, but energy consumption problems during the process of oil sewage treatment are worth attention. The integration of a constructed wetland reactor and a microbial fuel cell reactor (CW-MFC) to treat oil-contaminated wastewater, compared with a microbial fuel cell reactor (MFC) alone and a constructed wetland reactor (CW) alone, was explored in this research. Performances of the three reactors including chemical oxygen demand (COD), oil removal, and output voltage generation were continuously monitored...
November 1, 2016: Materials
Angel Perez Del Pino, Eniko Gyorgy, Islam Alshaikh, Fernando Pantoja-Suárez, José Luis Andújar, Esther Pascual, Roger Amade, Enric Bertran Serra
Carbon nanotubes-transition metal oxide systems are intensively studied due to their excellent properties for electrochemical applications. In this work, an innovative procedure is developed for the synthesis of vertically aligned multi-walled carbon nanotubes (VACNTs) coated with transition metal oxide nanostructures. VACNTs are grown by plasma enhanced chemical vapor deposition and coated with a manganese-based metal organic precursor (MOP) film based on manganese acetate solution. Subsequent UV pulsed laser irradiation induces the effective heating-decomposition of the MOP leading to the crystallization of manganese oxide nanostructures on the VACNT surface...
July 24, 2017: Nanotechnology
Łukasz Klapiszewski, Tadeusz J Szalaty, Beata Kurc, Małgorzata Stanisz, Andrzej Skrzypczak, Teofil Jesionowski
Kraft lignin (KL) was activated using selected ionic liquids (ILs). The activated form of the biopolymer, due to the presence of carbonyl groups, can be used in electrochemical tests. To increase the application potential of the system in electrochemistry, activated lignin forms were combined with manganese dioxide, and the most important physicochemical and morphological-microstructural properties of the novel, functional hybrid systems were determined using Fourier transform infrared spectroscopy (FTIR), elemental analysis (EA), scanning electron microscopy (SEM), zeta potential analysis, thermal stability (TGA/DTG) and porous structure analysis...
July 12, 2017: International Journal of Molecular Sciences
K Knížek, Z Jirák, O Kaman, M Maryško, F Damay
The magnetic ordering of four Tb(3+)-doped manganites and cobaltites, La0.7Tb0.1Sr0.2MnO3, La0.7Tb0.1Ca0.2MnO3, La0.7Tb0.1Sr0.2CoO3 and La0.7Tb0.1Ca0.2CoO3, have been studied by means of neutron diffraction and SQUID magnetometry. All the samples were prepared by sintering of sol-gel precursors and their orthorhombic or rhombohedral perovskite structures at room and low temperatures were refined. A long-range ferromagnetic (FM) order was detected at the Mn and Co sites. In addition, a small but significant ordered moment was observed at A sites of studied cobaltites, which was attributed to local Tb(3+) moments, aligned by exchange interactions due to FM ordered Co sublattice...
October 11, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Ahmed Amara Konaté, Huolin Ma, Heping Pan, Zhen Qin, Hafizullah Abba Ahmed, N'dji Dit Jacques Dembele
The availability of a deep well that penetrates deep into the Ultra High Pressure (UHP) metamorphic rocks is unusual and consequently offers a unique chance to study the metamorphic rocks. One such borehole is located in the southern part of Donghai County in the Sulu UHP metamorphic belt of Eastern China, from the Chinese Continental Scientific Drilling Main hole. This study reports the results obtained from the analysis of oxide log data. A geochemical logging tool provides in situ, gamma ray spectroscopy measurements of major and trace elements in the borehole...
June 29, 2017: Applied Radiation and Isotopes
Shengjie Wu, Mingjin Xie, Qin Zhang, Lijiang Zhong, Muhan Chen, Zhangjie Huang
Conventional separation methods are not suitable for recovering palladium present in low concentrations in ore leaching solutions. In this study, a novel isopentyl sulfide (S201)-impregnated α-MnO₂ nanorod adsorbent (BISIN) was prepared, characterized, and applied for the selective adsorption and separation of palladium from the leaching liquor of ores. Batch studies were carried out, and the main adsorption parameters were systematically investigated, in addition to the relevant thermodynamic parameters, isotherms, and kinetic models...
July 6, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
Hendrik Antoni, Wei Xia, Justus Masa, Wolfgang Schuhmann, Martin Muhler
Manganese oxides are promising electrocatalysts for the oxygen evolution reaction due to their versatile redox properties. Manganese oxide (MnOx) nanoparticles were synthesized on oxygen- and nitrogen-functionalized carbon nanotubes (OCNTs and NCNTs) by calcination in air of Mn-impregnated CNTs with a loading of 10 wt% Mn. The calcined samples were exposed to reducing conditions by thermal treatment in H2 or NH3, and to strongly oxidizing conditions using HNO3 vapor, which enabled us to flexibly tune the oxidation state of Mn from 2+ in MnO to 4+ in MnO2...
July 5, 2017: Physical Chemistry Chemical Physics: PCCP
Dipyaman Mohanta, Koushik Barman, Sk Jasimuddin, Md Ahmaruzzaman
Semiconducting nanomaterials are very important by means of their stability and wide band gap tunability. Visible light induced photoelectrocatalytic water oxidation based on these material are challenging as they have large band gap energies. Herein, we report that MnO doping can activate wide band gap semiconductors like SnO2 towards visible light induced water oxidation. Rutile SnO2 nanoparticles (band gap 3.6eV), usually absorbing at UV region, was capable of harvesting visible light when doped with MnO thereby minimizing the energy requirement for photoelctrocatalytic water splitting...
November 1, 2017: Journal of Colloid and Interface Science
V Esposito, M Fechner, R Mankowsky, H Lemke, M Chollet, J M Glownia, M Nakamura, M Kawasaki, Y Tokura, U Staub, P Beaud, M Först
We employ time-resolved resonant x-ray diffraction to study the melting of charge order and the associated insulator-to-metal transition in the doped manganite Pr_{0.5}Ca_{0.5}MnO_{3} after resonant excitation of a high-frequency infrared-active lattice mode. We find that the charge order reduces promptly and highly nonlinearly as function of excitation fluence. Density-functional theory calculations suggest that direct anharmonic coupling between the excited lattice mode and the electronic structure drives these dynamics, highlighting a new avenue of nonlinear phonon control...
June 16, 2017: Physical Review Letters
Mirosława Felsmann, Mirosław Michalski, Mariusz Felsmann, Rajmund Sokół, Józef Szarek, Emilia Strzyżewska-Worotyńska
[b]Abstract [/b] Dogs serve as the vectors of serious zoonotic parasitic diseases. In the month of May 2012 - 2014, 339 dog faeces samples from seven public sites in Chełmno, a town in northern Poland, were collected and examined to determine the gastrointestinal parasite fauna of dogs. Each faecal sample was dissected with a needle, checked for tapeworm segments and examined for parasite eggs and oocysts using the flotation and decantation method and a modified Baermann technique. Differences were observed in the degree of parasite species occurrence...
May 11, 2017: Annals of Agricultural and Environmental Medicine: AAEM
Burçak Ebin, Martina Petranikova, Britt-Marie Steenari, Christian Ekberg
Zinc (Zn) recovery from alkaline and zinc-carbon (Zn-C) battery waste were studied by a laboratory scale pyrolysis process at a reaction temperature of 950°C for 15-60min residence time using 5%H2(g)-N2(g) mixture at 1.0L/min gas flow rate. The effect of different cooling rates on the properties of pyrolysis residue, manganese oxide particles, were also investigated. Morphological and structural characterization of the produced Zn particles were performed. The battery black mass was characterized with respect to the properties and chemical composition of the waste battery particles...
June 21, 2017: Waste Management
R Logemann, A N Rudenko, M I Katsnelson, A Kirilyuk
Magnetism of transition metal (TM) oxides is usually described in terms of the Heisenberg model, with orientation-independent interactions between the spins. However, the applicability of such a model is not fully justified for TM oxides because spin polarization of oxygen is usually ignored. In the conventional model based on the Anderson principle, oxygen effects are considered as a property of the TM ion and only TM interactions are relevant. Here, we perform a systematic comparison between two approaches for spin polarization on oxygen in typical TM oxides...
August 23, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
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