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https://www.readbyqxmd.com/read/28812066/highly-stable-and-efficient-pd6-sr-12-cluster-catalysts-for-the-hydrogen-and-oxygen-evolution-reactions
#1
Xiaohui Gao, Wei Chen
Atomically precise Pd6(SC12H26)12 nanoclusters were synthesized and investigated as electrocatalysts for the hydrogen and oxygen evolution reactions. The present study shows the high catalytic performances of the Pd6 clusters, the key role of the outer-shell electronic state of the metal core in mediating the catalytic properties and the double-edged function of the protecting ligand in the catalytic reactions.
August 16, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/28810782/first-principles-molecular-dynamics-study-of-deuterium-diffusion-in-liquid-tin
#2
Xiaohui Liu, Daye Zheng, Xinguo Ren, Lixin He, Mohan Chen
Understanding the retention of hydrogen isotopes in liquid metals, such as lithium and tin, is of great importance in designing a liquid plasma-facing component in fusion reactors. However, experimental diffusivity data of hydrogen isotopes in liquid metals are still limited or controversial. We employ first-principles molecular dynamics simulations to predict diffusion coefficients of deuterium in liquid tin at temperatures ranging from 573 to 1673 K. Our simulations indicate faster diffusion of deuterium in liquid tin than the self-diffusivity of tin...
August 14, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28810123/electrochemical-dissolution-of-iridium-and-iridium-oxide-par-ticles-in-acidic-media-transmission-electron-microscopy-electrochemical-flow-cell-coupled-to-inductively-coupled-plasma-mass-spectrometry-and-x-ray-absorption-spectros-copy-study
#3
Primož Jovanovič, Nejc Hodnik, Francisco Ruiz-Zepeda, Iztok Arcon, Barbara Jozinović, Milena Zorko, Marjan Bele, Martin Šala, Vid Simon Šelih, Samo B Hocevar, Miran Gaberscek
Iridium based particles as the most promising proton exchange membrane electrolyser electrocatalysts were investigated by transmission electron microscopy (TEM), and by coupling of electrochemical flow cell (EFC) with online inductively coupled plasma mass spectrometer (ICP-MS). Additionally, a thin-film rotating disc electrode (RDE), an identical location trans-mission and scanning electron microscopy (IL-TEM and IL-SEM) as well as an X-ray absorption spectroscopy (XAS) studies have been performed. Extremely sensitive online time-and potential-resolved electrochemical dissolution profiles revealed that iridium particles dissolved already well below oxygen evolution reaction (OER) potentials, presumably induced by iridium surface oxidation and reduction processes, also referred to as transient dissolution...
August 15, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28809982/coordination-polymer-derived-nano-sized-zinc-ferrite-with-excellent-performance-in-nitro-explosive-detection
#4
Debal Kanti Singha, Partha Mahata
Herein, a mixed metal coordination polymer, {(H2pip)[Zn1/3Fe2/3(pydc-2,5)2(H2O)]·2H2O} 1 {where H2pip = piperazinediium and pydc-2,5 = pyridine-2,5-dicarboxylate}, was successfully synthesized using a hydrothermal technique. To confirm the structure and phase purity of 1, single crystals of an isomorphous pure Fe compound, {(H2pip)[Fe(pydc-2,5)2(H2O)]·2H2O} 1a, were synthesized based on similar synthetic conditions. Single crystal X-ray data of 1a confirmed the one-dimensional anionic metal-organic coordination polymer hydrogen bonded with protonated piprazine (piperazinediium) and lattice water molecules...
August 15, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/28809576/n-radical-initiated-aminosulfonylation-of-unactivated-c-sp-3-h-bond-through-insertion-of-sulfur-dioxide
#5
Yuewen Li, Runyu Mao, Jie Wu
N-Radical initiated aminosulfonylation of unactivated C(sp(3))-H bond through insertion of sulfur dioxide in the presence of visible light is reported. O-Aryl oximes react with DABCO·(SO2)2 smoothly at room temperature under blue LED irradiation without any metals or photoredox catalysts, generating diverse 5,6-dihydro-4H-1,2-thiazine 1,1-dioxides in good yield. Additionally, this approach can be extended to the synthesis of 1H-benzo[d][1,2]thiazine 2,2-dioxides. During the reaction process, an N-radical is initiated by the treatment of O-aryl oximes with DABCO·(SO2)2 under visible-light irradiation...
August 15, 2017: Organic Letters
https://www.readbyqxmd.com/read/28809534/ordered-and-atomically-perfect-fragmentation-of-layered-transition-metal-dichalcogenides-via-mechanical-instabilities
#6
Ming Chen, Juan Xia, Jiadong Zhou, Qingsheng Zeng, Kaiwei Li, Kazunori Fujisawa, Wei Fu, Ting Zhang, Jing Zhang, Zhe Wang, Zhixun Wang, Xiaoting Jia, Mauricio Terrones, Ze Xiang Shen, Zheng Liu, Lei Wei
Thermoplastic polymers subjected to a continuous tensile stress experience a state of mechanical instabilities, resulting in neck formation and propagation. The necking process with strong localized strain enables the transformation of initially brittle polymeric materials into robust, flexible, and oriented forms. Here we harness the polymer-based mechanical instabilities to control the fragmentation of atomically thin transition metal dichalcogenides (TMDs). We develop a simple and versatile nanofabrication tool to precisely fragment atom-thin TMDs sandwiched between thermoplastic polymers into ordered and atomically perfect TMD nanoribbons in arbitrary directions regardless of the crystal structures, defect content, and original geometries...
August 17, 2017: ACS Nano
https://www.readbyqxmd.com/read/28808708/a-graphitic-edge-plane-rich-meso-porous-carbon-anode-for-alkaline-water-electrolysis
#7
Dongyoon Shin, Myounghoon Choun, Hyung Chul Ham, Jae Kwang Lee, Jaeyoung Lee
There is growing interest in alkaline water electrolysis as a sustainable approach for producing hydrogen, but developing efficient and inexpensive catalysts for the oxygen evolution reaction, which can limit the operational efficiency of water electrolysis due to its considerable overpotential, is regarded as the most overriding challenge. Therefore, significant progress has been made in developing catalysts with transition metal and carbon materials as alternative catalysts. Here, we prepared cobalt containing carbon nanofibers via a facile route of electrospinning and pyrolysis, and metal leached carbon nanofibers were also prepared by subsequently leaching the metal...
August 15, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28806678/the-sorptive-and-reductive-capacities-of-biochar-supported-nanoscaled-zero-valent-iron-nzvi-in-relation-to-its-crystallite-size
#8
Shengsen Wang, Yanxia Zhou, Bin Gao, Xiaozhi Wang, Xianqiang Yin, Ke Feng, Jun Wang
In this work, nZVI was immobilized by bamboo derived biochars (nZVI/BB), hydrogen peroxide (H2O2) (nZVI/PBB) and nitric acid (HNO3) (nZVI/HBB) modified BB. H2O2 and HNO3 deceased surface area and pore volume of pristine biochars. Total iron (Fe) contents were 16.50, 24.40, and 13.08% for nZVI/BB, nZVI/PBB and nZVI/HBB, respectively. The X-ray diffraction revealed that nZVI in biochar matrix was dominantly metallic Fe coated with Fe oxides. The transmission electron microscopy indicated nZVI particle sizes were 41...
August 7, 2017: Chemosphere
https://www.readbyqxmd.com/read/28805825/the-processing-and-heterostructuring-of-silk-with%C3%A2-light
#9
Mehra S Sidhu, Bhupesh Kumar, Kamal P Singh
Spider silk is a tough, elastic and lightweight biomaterial, although there is a lack of tools available for non-invasive processing of silk structures. Here we show that nonlinear multiphoton interactions of silk with few-cycle femtosecond pulses allow the processing and heterostructuring of the material in ambient air. Two qualitatively different responses, bulging by multiphoton absorption and plasma-assisted ablation, are observed for low- and high-peak intensities, respectively. Plasma ablation allows us to make localized nanocuts, microrods, nanotips and periodic patterns with minimal damage while preserving molecular structure...
August 14, 2017: Nature Materials
https://www.readbyqxmd.com/read/28805657/noble-metal-free-tungsten-oxide-carbon-wox-c-hybrid-nanowires-for-highly-efficient-hydrogen-evolution
#10
Changhai Liu, Yangyang Qiu, Yujian Xia, Fang Wang, Xiaocun Liu, Xuhui Jeff Sun, Qian Liang, Zhidong Chen
Developing active, stable, and low-cost electrocatalysts to generate hydrogen is a great challenge in the fields of chemistry and energy. The nonprecious metal catalysts comprised of inexpensive and earth-abundant transition metals, regarded as promising substitute for noble metal catalysts used in hydrogen evolution reaction (HER), are still practically unfeasible mainly due to unsatisfactory activity and durability. Here we report the facile two-step preparation method for WOx nanowires with high concentration of oxygen vacancies (OVs) via calcination of W-polydopamine compound precursors...
August 14, 2017: Nanotechnology
https://www.readbyqxmd.com/read/28805063/hierarchical-porous-co9s8-nitrogen-doped-carbon-mos2-polyhedrons-as-ph-universal-electrocatalysts-for-highly-efficient-hydrogen-evolution-reaction
#11
Hongmei Li, Xing Qian, Chong Xu, Shaowei Huang, Changli Zhu, Xiancai Jiang, Li Shao, Linxi Hou
The development of highly active and stable earth-abundant electrocatalysts to reduce or eliminate the reliance on noble-metal based ones for hydrogen evolution reaction (HER) over a broad pH range remains a great challenge. Herein, hierarchical porous Co9S8/N-doped carbon@MoS2 (Co9S8/NC@MoS2) polyhedrons have been synthesized by a facile hydrothermal approach using highly conductive Co/NC polyhedrons composed of cobalt nanoparticles embedded in N-doped carbon matrices as both the structural support and cobalt source...
August 14, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28803411/electro-chemical-deposition-of-nano-hydroxyapatite-zinc-coating-on-titanium-metal-substrate
#12
N A El-Wassefy, F M Reicha, N S Aref
BACKGROUND: Titanium is an inert metal that does not induce osteogenesis and has no antibacterial properties; it is proposed that hydroxyapatite coating can enhance its bioactivity, while zinc can contribute to antibacterial properties and improve osseointegration. AIMS: A nano-sized hydroxyapatite-zinc coating was deposited on commercially pure titanium using an electro-chemical process, in order to increase its surface roughness and enhance adhesion properties...
August 13, 2017: International Journal of Implant Dentistry
https://www.readbyqxmd.com/read/28803102/kinetics-of-the-release-of-elemental-precursors-of-syngas-and-syngas-contaminants-during-devolatilization-of-switchgrass
#13
Oluwafemi Oyedeji, Charles Stuart Daw, Nicole Labbe, Paul Ayers, Nourredine Abdoulmoumine
In this study, the results from laboratory measurements of the devolatilization kinetics of switchgrass in a rapidly heated fixed bed reactor flushed with argon and operated at constant temperatures between 600 and 800°C was reported. Results indicate that switchgrass decomposes in two sequential stages during pyrolysis: stage I involves the evaporation and devolatilization of water and extractives and stage II involves that of hemicellulose, cellulose, and lignin. The estimated global activation energy for stage II increased from 52...
July 29, 2017: Bioresource Technology
https://www.readbyqxmd.com/read/28802272/transcriptional-analysis-of-an-ammonium-excreting-strain-of-azotobacter-vinelandii-deregulated-for-nitrogen-fixation
#14
Brett M Barney, Mary H Plunkett, Velmurugan Natarajan, Florence Mus, Carolann M Knutson, John W Peters
Biological nitrogen fixation is accomplished by a diverse group of organisms known as diazotrophs, and requires the function of the complex metalloenzyme nitrogenase. Nitrogenase and many of the accessory proteins required for proper cofactor biosynthesis and incorporation into the enzyme have been characterized, but a complete picture of the reaction mechanism and key cellular changes that accompany biological nitrogen fixation remain to be fully elucidated. Studies have revealed that specific disruptions to the anti-activator encoding gene nifL result in the deregulation of the nif transcriptional activator NifA in the nitrogen-fixing bacterium Azotobacter vinelandii, triggering the production of extracellular ammonium levels approaching 30 mM during the stationary phase of growth...
August 11, 2017: Applied and Environmental Microbiology
https://www.readbyqxmd.com/read/28802247/effect-of-lead-speciation-on-its-oral-bioaccessibility-in-surface-dust-and-soil-of-electronic-wastes-recycling-sites
#15
Takashi Fujimori, Masaya Taniguchi, Tetsuro Agusa, Kenji Shiota, Masaki Takaoka, Aya Yoshida, Atsushi Terazono, Florencio C Ballesteros, Hidetaka Takigami
We measured bioaccessible lead (Pb) in simulated gastrointestinal fluids containing Pb-contaminated soil or dust from electronic waste (e-waste) recycling sites to assess the risk of Pb ingestion. The physiologically based extraction test (PBET) was used as in vitro bioaccessibility assay. Pb speciation was determined using X-ray absorption spectroscopy. The total Pb concentrations in dusts (n=8) and soils (n=4) were in the range of 1630-131,000 and 239-7800mg/kg, respectively. Metallic Pb, a common component of e-waste, was ubiquitous in the samples...
August 4, 2017: Journal of Hazardous Materials
https://www.readbyqxmd.com/read/28801872/new-hybrid-nanocomposite-of-copper-terephthalate-mof-graphene-oxide-synthesis-characterization-and-application-as-adsorbents-for-toxic-metal-ion-removal-from-sungun-acid-mine-drainage
#16
Esmaeil Rahimi, Neda Mohaghegh
The application of a hybrid Cu(tpa).GO (Cu(tpa) copper terephthalate metal organic framework, GO graphene oxide) composite as a new adsorbent for the removal of toxic metal ions was reported. New hybrid nanocomposite with excellent dispersibility and stability was successfully fabricated by the simple and effective ultrasonication method. The synthesized composite was characterized by scanning electron microscopy (SEM), UV-Vis and Fourier-transform infrared (FT-IR) techniques. The characterization results concluded that the binding mechanism of the Cu(tpa) and GO was related to both π-π packing and hydrogen bonding...
August 11, 2017: Environmental Science and Pollution Research International
https://www.readbyqxmd.com/read/28799586/elucidating-the-impact-of-a-site-cation-change-on-photocatalytic-h2-and-o2-evolution-activities-of-perovskite-type-lntaon2-ln-la-and-pr
#17
Mirabbos Hojamberdiev, Maged F Bekheet, Judy N Hart, Junie Jhon M Vequizo, Akira Yamakata, Kunio Yubuta, Aleksander Gurlo, Masashi Hasegawa, Kazunari Domen, Katsuya Teshima
Transition metal (oxy)nitrides with perovskite-type structures have been regarded as one of the promising classes of inorganic semiconductor materials that can be used in solar water splitting systems for the production of hydrogen as a renewable and storable energy carrier. The performance of transition metal (oxy)nitrides in solar water splitting is strongly influenced by the crystal structure-related dynamics of photogenerated charge carriers. Here, we have systematically assessed the influence of A-site cation exchange on the visible-light-induced photocatalytic H2 and O2 evolution activities, photoanodic response, and dynamics of photogenerated charge carriers of perovskite-type LnTaON2 (Ln = La and Pr)...
August 11, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28799204/electrochemical-reduction-of-carbon-dioxide-in-a-monoethanolamine-capture-medium
#18
Jie Zhang, Lu Chen, Fengwang Li, Ying Zhang, Cameron Bentley, Mike Horne, Alan Bond
Electrocatalytic reduction of CO2 present in a 30% (w/w) monoethanolamine (MEA) aqueous solution has been undertaken at In, Sn, Bi, Pb, Pd, Ag, Cu and Zn metal electrodes. Upon dissolution of CO2, the non-conducting MEA solution is transformed into a conducting one, as needed for electrochemical reduction of CO2. Both an increase in the electrode surface porosity and addition of surfactant cetyltrimethylammonium bromide (CTAB) suppress the competing hydrogen evolution reaction with the latter having a significantly stronger impact...
August 10, 2017: ChemSusChem
https://www.readbyqxmd.com/read/28798958/biofunctionalized-conductive-polymers-enable-efficient-co2-electroreduction
#19
Halime Coskun, Abdalaziz Aljabour, Phil De Luna, Dominik Farka, Theresia Greunz, David Stifter, Mahmut Kus, Xueli Zheng, Min Liu, Achim W Hassel, Wolfgang Schöfberger, Edward H Sargent, Niyazi Serdar Sariciftci, Philipp Stadler
Selective electrocatalysts are urgently needed for carbon dioxide (CO2) reduction to replace fossil fuels with renewable fuels, thereby closing the carbon cycle. To date, noble metals have achieved the best performance in energy yield and faradaic efficiency and have recently reached impressive electrical-to-chemical power conversion efficiencies. However, the scarcity of precious metals makes the search for scalable, metal-free, CO2 reduction reaction (CO2RR) catalysts all the more important. We report an all-organic, that is, metal-free, electrocatalyst that achieves impressive performance comparable to that of best-in-class Ag electrocatalysts...
August 2017: Science Advances
https://www.readbyqxmd.com/read/28798900/recent-advances-in-unveiling-active-sites-in-molybdenum-sulfide-based-electrocatalysts-for-the-hydrogen-evolution-reaction
#20
REVIEW
Bora Seo, Sang Hoon Joo
Hydrogen has received significant attention as a promising future energy carrier due to its high energy density and environmentally friendly nature. In particular, the electrocatalytic generation of hydrogen fuel is highly desirable to replace current fossil fuel-dependent hydrogen production methods. However, to achieve widespread implementation of electrocatalytic hydrogen production technology, the development of highly active and durable electrocatalysts based on Earth-abundant elements is of prime importance...
2017: Nano Convergence
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