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https://www.readbyqxmd.com/read/28934608/chemical-free-fabrication-of-n-p-dual-doped-honeycomb-like-carbon-as-an-efficient-electrocatalyst-for-oxygen-reduction
#1
Lianwen Zhu, Jun Wu, Qiao Zhang, Xiangkui Li, Yiming Li, Xuebo Cao
Heteroatom-doped nanoporous carbons are now emerging as alternatives to platinum and its alloys as electrocatalysts to facilitate oxygen reduction reaction in metal-air batteries and fuel cells. However, the synthesis of nanoporous carbons usually involve in complicated procedures and intensive chemicals, which may dramatically raise their manufacture cost that even surpasses that of precious platinum. Herein, we demonstrate the single-step, chemical-free fabrication of N, P dualdoped honeycomb carbon that has hierarchically porous structure and oxygen electrocatalysis activity close to the benchmark Pt/C...
August 23, 2017: Journal of Colloid and Interface Science
https://www.readbyqxmd.com/read/28934104/microwave-deposition-of-palladium-catalysts-on-graphite-spheres-and-reduced-graphene-oxide-sheets-for-electrochemical-glucose-sensing
#2
Jian-De Xie, Siyong Gu, Houan Zhang
This work outlines a synthetic strategy inducing the microwave-assisted synthesis of palladium (Pd) nanocrystals on a graphite sphere (GS) and reduced graphene oxide (rGO) supports, forming the Pd catalysts for non-enzymatic glucose oxidation reaction (GOR). The pulse microwave approach takes a short period (i.e., 10 min) to fast synthesize Pd nanocrystals onto a carbon support at 150 °C. The selection of carbon support plays a crucial role in affecting Pd particle size and dispersion uniformity. The robust design of Pd-rGO catalyst electrode displays an enhanced electrocatalytic activity and sensitivity toward GOR...
September 21, 2017: Sensors
https://www.readbyqxmd.com/read/28933830/immobilized-cobalt-bis-benzenedithiolate-complexes-exceptionally-active-heterogeneous-electrocatalysts-for-dihydrogen-production-from-mildly-acidic-aqueous-solutions
#3
Shawn C Eady, Molly M MacInnes, Nicolai Lehnert
A series of cobalt bis(benzenedithiolate) complexes with varying benzenedithiolate (general abbreviation: bdt(2-)) ring substitutions (S2C6X4(2-)) were prepared and adsorbed on inexpensive electrodes composed of (a) reduced graphene oxide (RGO) electrodeposited on fluorine-doped tin oxide (FTO) and (b) highly ordered pyrolytic graphite (HOPG). The catalyst-adsorbed electrodes are characterized by X-ray photoelectron spectroscopy. Catalyst loading across the ligand series improved notably with increasing halide substitution [from 2...
September 21, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28931877/laser-plasma-driven-synthesis-of-carbon-based-nanomaterials
#4
M Barberio, P Antici
In this paper we introduce a laser-plasma driven method for the production of carbon based nanomaterials and in particular bi- and few-layers of Graphene. This is obtained by using laser-plasma exfoliation of amorphous Graphite in a liquid solution, employing a laser with energy in the order of 0.5 J/mm(2). Raman and XPS analysis of a carbon colloidal performed at different irradiation stages indicate the formation of Graphene multilayers with an increasing number of layers: the amount of layers varies from a monolayer obtained in the first few seconds of the laser irradiation, up to two layers obtained after 10 s, and finally to Graphite and amorphous carbon obtained after 40 s of irradiation...
September 20, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28931819/silicate-dissolution-boosts-the-co2-concentrations-in-subduction-fluids
#5
S Tumiati, C Tiraboschi, D A Sverjensky, T Pettke, S Recchia, P Ulmer, F Miozzi, S Poli
Estimates of dissolved CO2 in subduction-zone fluids are based on thermodynamic models, relying on a very sparse experimental data base. Here, we present experimental data at 1-3 GPa, 800 °C, and ∆FMQ ≈ -0.5 for the volatiles and solute contents of graphite-saturated fluids in the systems COH, SiO2-COH ( + quartz/coesite) and MgO-SiO2-COH ( + forsterite and enstatite). The CO2 content of fluids interacting with silicates exceeds the amounts measured in the pure COH system by up to 30 mol%, as a consequence of a decrease in water activity probably associated with the formation of organic complexes containing Si-O-C and Si-O-Mg bonds...
September 20, 2017: Nature Communications
https://www.readbyqxmd.com/read/28930632/co2-absorption-in-the-ionic-liquids-immobilized-on-solid-surface-by-molecular-dynamics-simulation
#6
Ziqian Tang, Linghong Lu, Zhongyang Dai, Wenlong Xie, Lili Shi, Xiaohua Lu
Based on our previous experimental research, we studied the absorption of CO2 in the ionic liquid, 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([hmim][Tf2N] ), immobilized on TiO2 [rutile (110) ] with different thickness by molecular dynamics simulation. The effects of the properties (hydrophobicity and hydrophilicity) of solid interfaces were also studied with IL immobilized on graphite and TiO2 respectively. We studied the influence of the thickness of IL immobilized on TiO2 on the absorption of CO2 via structural and dynamical properties...
September 20, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28930344/electron-dynamics-in-mos2-graphite-heterostructures
#7
Xinwu Zhang, Dawei He, Lixin Yi, Siqi Zhao, Jiaqi He, Yongsheng Wang, Hui Zhao
The electron dynamics in heterostructures formed by multilayer graphite and monolayer or bulk MoS2 were studied by femtosecond transient absorption measurements. Samples of monolayer MoS2-multilayer graphite and bulk MoS2-multilayer graphite were fabricated by exfoliation and dry transfer techniques. Ultrafast laser pulses were used to inject electron-hole pairs into monolayer or bulk MoS2. The transfer of these photocarriers to the adjacent multilayer graphite was time resolved by measuring the differential reflection of a probe pulse...
September 20, 2017: Nanoscale
https://www.readbyqxmd.com/read/28929741/visible-light-neural-stimulation-on-graphitic-carbon-nitride-graphene-photocatalytic-fibers
#8
Zhongyang Zhang, Ruodan Xu, Zegao Wang, Mingdong Dong, Bianxiao Cui, Menglin Chen
Light stimulation allows remote and spatiotemporally accurate operation that has been applied as effective, non-invasive means of therapeutic interventions. Here, visible light neural stimulation of graphitic carbon nitride (g-C3N4), an emerging photocatalyst with visible-light optoelectronic conversion, was for the first time investigated. Specifically, g-C3N4 was combined with graphene oxide (GO) in a 3D manner on the surfaces of electrospun polycaprolactone/gelatin (PG) fibers and functioned as a biocompatible interface for visible-light stimulating neuronal differentiation...
September 20, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28928477/a-generic-method-to-synthesise-graphitic-carbon-coated-nanoparticles-in-large-scale-and-their-derivative-polymer-nanocomposites
#9
Nannan Wang, Zhuxian Yang, Fang Xu, Kunyapat Thummavichai, Hongmei Chen, Yongde Xia, Yanqiu Zhu
A versatile Rotary Chemical Vapour Deposition (RCVD) technique for the in-situ synthesis of large scale carbon-coated non-magnetic metal oxide nanoparticles (NPs) is presented, and a controllable coating thickness varying between 1-5 nm has been achieved. The technique has significantly up-scaled the traditional chemical vapour deposition (CVD) production for NPs from mg level to 10 s of grams per batch, with the potential for continuous manufacturing. The resulting smooth and uniform C-coatings sheathing the inner core metal oxide NPs are made of well-crystallised graphitic layers, as confirmed by electron microscopy imaging, electron dispersive spectrum elemental line scan, X-ray powder diffractions and Raman spectroscopy...
September 19, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28926695/architecting-mesoporous-n-doped-graphitic-carbon-framework-encapsulating-cote2-as-efficient-oxygen-evolution-electrocatalyst
#10
Ming Liu, Xiaoqing Lu, Chen Guo, Zhaojie Wang, Yanpeng Li, Yan Lin, Yan Zhou, Shutao Wang, Jun Zhang
To improve the efficiency of cobalt-based catalysts for water electrolysis, tremendous efforts have been dedicated to tuning the composition, morphology, size and structure of the materials. We report here the facile preparation of orthorhombic CoTe2 nanocrystals embedded in N-doped graphitic carbon matrix to form a 3D architecture with a size of ~500 nm and abundant mesopores of ~4 nm for the oxygen evolution reaction. The hybrid electrocatalyst delivers a small overpotential of 300 mV at 10 mA cm-2, which is much lower than that for pristine CoTe2 powder...
September 19, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28926223/supramolecular-motors-on-graphite-surface-stabilized-by-charge-states-and-hydrogen-bonds
#11
Kai Sun, Ji-Yong Luo, Xin Zhang, Zhi-Jian Wu, Ying Wang, Hong-Kuan Yuan, Zu-Hong Xiong, Shao-Chun Li, Qi-Kun Xue, Jun-Zhong Wang
Molecular motors are nanoscale machines that convert external energies into controlled mechanical movements. In supramolecular motors, the rotator and stator are held together mechanically, and thus the rotation can be essentially barrier free when molecular conformation is negligible. However, nearly all the supramolecular motors appeared in solutions or host-guest complexes. Surface-mounted supramolecular motors have rarely been addressed, even though they are easily manipulated by external fields. Here we report a surface-mounted supramolecular motor assembled by charge states and hydrogen bonds...
September 19, 2017: ACS Nano
https://www.readbyqxmd.com/read/28926062/selectivity-of-solid-phase-extraction-for-dissolved-organic-matter-in-the-hypersaline%C3%A2-da-qaidam-lake-china
#12
Keli Yang, Yaoling Zhang, Yaping Dong, Wu Li
Dissolved organic matter (DOM) was isolated from the hypersaline Da Qaidam Lake using solid-phase extraction (SPE) methods with five different adsorbents: ENVI-Carb (non-porous graphitized carbon), HLB, PPL, and XAD-8 (polymer based), and ENVI-18 (silica based). Structure-selective assessments of SPE-DOM isolated using the different adsorbents were conducted using a combination of complementary analysis techniques, including dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) analysis, as well as elemental analysis, Fourier transformed infrared spectroscopy (FTIR), (1)H nuclear magnetic resonance ((1)H NMR) and pyrolysis-gas chromatography-mass spectrometry (Py-GC/MS)...
September 19, 2017: Environmental Science. Processes & Impacts
https://www.readbyqxmd.com/read/28926044/running-out-of-lithium-a-route-to-differentiate-between-capacity-losses-and-active-lithium-losses-in-lithium-ion-batteries
#13
Florian Holtstiege, Andrea Wilken, Martin Winter, Tobias Placke
Active lithium loss (ALL) resulting in a capacity loss (QALL), which is caused by lithium consuming parasitic reactions like SEI formation, is a major reason for capacity fading and, thus, for a reduction of the usable energy density of lithium-ion batteries (LIBs). QALL is often equated with the accumulated irreversible capacity (QAIC). However, QAIC is also influenced by non-lithium consuming parasitic reactions, which do not reduce the active lithium content of the cell, but induce a parasitic current. In this work, a novel approach is proposed in order to differentiate between QAIC and QALL...
September 19, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28926043/new-complete-assignment-of-x-ray-powder-diffraction-patterns-in-graphitic-carbon-nitride-using-discrete-fourier-transform-and-direct-experimental-evidence
#14
Bo-Wen Sun, Hong-Yu Yu, Yong-Jing Yang, Hui-Jun Li, Cheng-Yu Zhai, Dong-Jin Qian, Meng Chen
To date, there have been only a few studies focusing on the assignment of X-ray diffraction (XRD) patterns in graphitic carbon nitrides (g-C3N4) and contradictory determination for a broad peak around 12°-14° has been perplexing. In this study, assignments are carried out both theoretically and experimentally. The cell parameters for g-C3N4 are determined as a = b = 8.1 Å, c = 6.5 Å, α = β = 90°, and γ = 120°. Qualitative and semi-quantitative methods such as fast Fourier transform and residual after 1st and 2nd derivatives are used to confirm and search the hidden peaks...
September 19, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28925713/simple-and-efficient-fabrication-of-mayenite-electrides-from-a-solution-derived-precursor
#15
Dong Jiang, Zeyu Zhao, Shenglong Mu, Vincent Phaneuf, Jianhua Tong
Mayenite (12CaO·7Al2O3, C12A7) electride with an anti-zeolite nanoporous structure has attracted intense attention due to its versatile promising application potentials. However, the synthesis difficulty because of extremely harsh conditions (e.g., reduction in sealed calcium or titanium vapor) significantly obstructs its realistic applications. In this work, we employed a simple, efficient, and cost-effective route for synthesizing mayenite electrides (C12A7:e(-)) in both powder and dense ceramic. C12A7:e(-) powders with efficient electron doping (3...
September 19, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28924301/epitaxial-graphene-homogeneity-and-quantum-hall-effect-in-millimeter-scale-devices
#16
Yanfei Yang, Guangjun Cheng, Patrick Mende, Irene G Calizo, Randall M Feenstra, Chiashain Chuang, Chieh-Wen Liu, Chieh-I Liu, George R Jones, Angela R Hight Walker, Randolph E Elmquist
Quantized magnetotransport is observed in 5.6 × 5.6 mm(2) epitaxial graphene devices, grown using highly constrained sublimation on the Si-face of SiC(0001) at high temperature (1900 °C). The precise quantized Hall resistance of [Formula: see text] is maintained up to record level of critical current Ixx = 0.72 mA at T = 3.1 K and 9 T in a device where Raman microscopy reveals low and homogeneous strain. Adsorption-induced molecular doping in a second device reduced the carrier concentration close to the Dirac point (n ≈ 10(10) cm(-2)), where mobility of 18760 cm(2)/V is measured over an area of 10 mm(2)...
May 2017: Carbon
https://www.readbyqxmd.com/read/28920916/monovacancy-paramagnetism-in-neutron-irradiated-graphite-probed-by-sup-13-sup-c-nmr
#17
Zhi Tao Zhang, C Xu, Daryna Dmytriieva, Sebastian Molatta, J Wosnitza, Y T Wang, Manfred Helm, Shengqiang Zhou, Hannes Kuehne
We report on the magnetic properties of monovacancy defects in neutron-irradiated graphite, probed by $^{13}$C nuclear magnetic resonance spectroscopy. The bulk paramagnetism of the defect moments is revealed by the temperature dependence of the NMR frequency shift and spectral linewidth, both of which follow a Curie behavior, in agreement with measurements of the macroscopic magnetization. Compared to pristine graphite, the fluctuating hyperfine fields generated by the defect moments lead to an enhancement of the $^{13}$C nuclear spin-lattice relaxation rate $1/T_{1}$ by about two orders of magnitude...
September 18, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/28920701/absence-of-a-band-gap-at-the-interface-of-a-metal-and-highly-doped-monolayer-mos2
#18
Alexander Kerelsky, Ankur Nipane, Drew Edelberg, Dennis Wang, Xiaodong Zhou, Abdollah Motmaendadgar, Hui Gao, Saien Xie, Kibum Kang, Jiwoong Park, James Teherani, Abhay Pasupathy
High quality electrical contact to semiconducting transition metal dichalcogenides (TMDCs) such as MoS2 is key to unlocking their unique electronic and optoelectronic properties for fundamental research and device applications. Despite extensive experimental and theoretical efforts reliable ohmic contact to doped TMDCs remains elusive and would benefit from a better understanding of the underlying physics of the metal-TMDC interface. Here we present measurements of the atomic-scale energy band diagram of junctions between various metals and heavily doped monolayer MoS2 using ultrahigh vacuum scanning tunneling microscopy (UHV-STM)...
September 20, 2017: Nano Letters
https://www.readbyqxmd.com/read/28920670/fabrication-of-hierarchical-porous-carbon-nanoflakes-for-high-performance-supercapacitors
#19
Yamin Yao, Yunqiang Zhang, Li Li, Shulan Wang, Shi Xue Dou, Xuan Liu
In the current work, the carbon nanoflakes (CNs-Fe/KOH) and porous carbon (PC-Ni/KOH) have been produced by using Fe(NO3)3/KOH and Ni(NO3)2/KOH as the co-graphitization/activation catalysts to treat the natural plane tree fluff, respectively. The as-prepared carbon materials show different morphologies when treated with different metal ions. Compared with PC-Ni/KOH, the CNs-Fe/KOH have both high graphitization degree (IG/ID = 1.53) and large SBET (1416 m2/g). In a three-electrode setup, the CNs-Fe/KOH electrode shows a high specific capacitance of 253 F/g at 10 A/g, with a capacitance retention of 92...
September 18, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28918372/enhanced-visible-light-photocatalytic-nitrogen-fixation-over-semicrystalline-graphitic-carbon-nitride-oxygen-and-sulfur-co-doping-for-crystal-and-electronic-structure-modulation
#20
Xiangwen Feng, Huan Chen, Fang Jiang, Xin Wang
Oxygen and sulfur co-doped semicrystalline graphitic carbon nitride (HGCNOS) was synthesized by a one-pot hydrothermal method and applied in visible-light photocatalytic nitrogen fixation. Remarkably, HGCNOS exhibited a higher photocatalytic activity than pristine graphitic carbon nitride (GCN). Oxygen doping caused semicrystalline structure, making exciton dissociated at the order-disorder interfaces of HGCNOS and releasing more electrons and holes. Furthermore, the conduction band position of HGCNOS was elevated by sulfur doping, promoting the reduction ability of HGCNOS...
September 8, 2017: Journal of Colloid and Interface Science
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