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Jiong Wang, Xiaoming Ge, Zhaolin Liu, Larissa Thia, Ya Yan, Wei Xiao, Xin Wang
Molecular Co2+ ions were grafted onto doped graphene in a coordination environment, resulting in the formation of molecularly well-defined, highly active electrocatalytic sites at a heterogeneous interface for the oxygen evolution reaction (OER). The S dopants of graphene are suggested to be one of the binding sites and to be responsible for improving the intrinsic activity of the Co sites. The turnover frequency of such Co sites is greater than that of many Co-based nanostructures and IrO2 catalysts. Through a series of carefully designed experiments, the pathway for the evolution of the Co cation-based molecular catalyst for the OER was further demonstrated on such a single Co-ion site for the first time...
January 18, 2017: Journal of the American Chemical Society
Wenxiu Yang, Lulu Chen, Xiangjian Liu, Jianbo Jia, Shaojun Guo
Herein, a novel material with an excellent electrocatalytic activity for the oxygen reduction reaction (ORR), composed of onion-like carbon@Co nanoparticles (NPs) incorporated on defect-rich N-doped graphene nanoribbons (C@Co-NGR), is prepared via a combination of nitric acid etching and subsequent high-temperature treatment of the as-synthesized C@Co-N doped carbon nanotubes. The as-prepared C@Co-NGR exhibits excellent electrocatalytic activity for the ORR in 0.10 M KOH with a half-wave potential of 0.830 V (vs...
January 16, 2017: Nanoscale
Mikaela Goerlin, Jorge Ferreira de Araújo, Henrike Schmies, Denis Bernsmeier, Soeren Dresp, Manuel Gliech, Zenonas Jusys, Petko Chernev, Ralph Kraehnert, Holger Dau, Peter Strasser
Ni-Fe oxyhydroxides are the most active known electrocatalysts for the oxygen evolution reaction (OER) in alkaline electrolytes and are therefore of great scientific and technological importance in the context of electrochemical energy conversion. Here we uncover, investigate, and discuss previously unaddressed effects of conductive supports and the electrolyte pH on the Ni-Fe oxide catalyst redox behavior and catalytic OER activity, combining operando UV-vis spectro-electrochemistry, operando electrochemical mass spectrometry (DEMS), and in-situ cryo X-ray absorption spectroscopy (XAS)...
January 12, 2017: Journal of the American Chemical Society
Bingya Hou, Lang Shen, Haotian Shi, Rehan Kapadia, Stephen B Cronin
We report measurements of photocatalytic water splitting using Au films with and without TiO2 coatings. In these structures, a thin (3-10 nm) film of TiO2 is deposited using atomic layer deposition (ALD) on top of a 100 nm thick Au film. We utilize an AC lock-in technique, which enables us to detect the relatively small photocurrents (∼μA) produced by the short-lived hot electrons that are photoexcited in the metal. Under illumination, the bare Au film produces a small AC photocurrent (<1 μA) for both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) due to hot electrons and hot holes, respectively, that are photoexcited in the Au film...
January 11, 2017: Physical Chemistry Chemical Physics: PCCP
Kun Xu, Han Cheng, Linqi Liu, Haifeng Lv, Xiaojun Wu, Changzheng Wu, Yi Xie
In this study, by using dicobalt phosphide nanoparticles as precatalysts, we demonstrated that electrochemical activation of metallic precatalysts in alkaline media (comparing with directly electrochemical activation in neutral media) could significantly promote the OER catalysis in neutral media, specifically realizing a 2-fold enhanced activity and meanwhile showing a greatly decreased overpotential of about 100 mV at 10 mA cm(-2). Compared directly with electrochemical activation in neutral media, the electrochemical activation in harsh alkaline media could easily break the strong Co-Co bond and promote active species generation on the surface of metallic Co2P, thus accounting for the enhancement of neutral OER activity, which is also evidenced by HRTEM and the electrochemical double-layer capacitance measurement...
January 11, 2017: Nano Letters
Shuo Zhao, Renxi Jin, Hadi Abroshan, Chenjie Zeng, Hui Zhang, Stephen D House, Eric Gottlieb, Hyung J Kim, Judith C Yang, Rongchao Jin
Electrocatalytic water splitting to produce hydrogen comprises the hydrogen and oxygen evolution half reactions (HER and OER), with the latter as the bottleneck process. Thus, enhancing the OER performance and understanding the mechanism are critically important. Herein, we report a strategy for OER enhancement by utilizing gold nanoclusters to form cluster/CoSe2 composites; the latter exhibit largely enhanced OER activity in alkaline solutions. The Au25/CoSe2 composite affords a current density of 10 mA cm-2 at small overpotential of ~0...
January 9, 2017: Journal of the American Chemical Society
Ruquan Ye, Yuanyue Liu, Zhiwei Peng, Tuo Wang, Almaz S Jalilov, Boris I Yakobson, Su-Huai Wei, James M Tour
The development of catalytic materials for the hydrogen oxidation, hydrogen evolution, oxygen reduction or oxygen evolution reactions with high reaction rates and low overpotentials are key goals for the development of renewable energy. We report here Ru(0) nanoclusters supported on nitrogen-doped graphene as high-performance multifunctional catalysts for the hydrogen evolution reaction (HER) and oxygen reduction reaction (ORR), showing activities similar to that of commercial Pt/C in alkaline solution. For HER performance in alkaline media, sample Ru/NG-750 reaches 10 mA cm(-2) at an overpotential of 8 mV with a Tafel slope of 30 mV dec(-1)...
January 18, 2017: ACS Applied Materials & Interfaces
Dieter J A Heylen, Hein Sprong, Aleksandra Krawczyk, Natalie Van Houtte, Dolores Genné, Andrea Gomez-Chamorro, Kees van Oers, Maarten J Voordouw
The spirochete bacterium Borrelia afzelii is the most common cause of Lyme borreliosis in Europe. This tick-borne pathogen can establish systemic infections in rodents but not in birds. However, several field studies have recovered larval Ixodes ricinus ticks infected with B. afzelii from songbirds suggesting successful transmission of B. afzelii. We reviewed the literature to determine which songbird species were the most frequent carriers of B. afzelii-infected I. ricinus larvae and nymphs. We tested experimentally whether B...
January 5, 2017: Scientific Reports
M Kissick, D Campos, V Desai, L Che Fru
PURPOSE: Local oxygen during a radiotherapy fraction has been shown to change over a full range of the oxygen enhancement ratio (OER) during the same time scale as the treatment fraction. Interplay with local oxygen is then likely a concern, especially for hypofractionation. Our experiments that show a strong role for metabolic dynamics suggesting one could manipulate this interplay for more efficacious treatments. METHODS: Two published experiments are presented with the same human head and neck cancer cell line (UM-SCC-22B)...
June 2016: Medical Physics
Tianli Wu, Mingyu Pi, Xiaodeng Wang, Dingke Zhang, Shijian Chen
Developing low-cost and highly-efficient non-precious metal bifunctional electrocatalysts towards the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is an attractively alternative strategy to solve the environmental pollution problems and energy demands. In this study, metal-organic framework (MOF) derived porous cobalt poly-phosphide (CoP3) concave polyhedrons are prepared and explored as superior bifunctional electrocatalysts for the HER and OER. The prepared MOF derived CoP3 concave polyhedrons show excellent electrocatalytic activity and stability towards the HER and OER in both acidic and alkaline media, with the Tafel slopes of 53 mV dec(-1) and 76 mV dec(-1) and a current density of 10 mA cm(-2) at the overpotentials of -78 and 343 mV for the HER and OER, respectively, which are remarkably superior to those of the transition metal phosphides (TMPs) and comparable to those of the commercial precious metal catalysts...
January 18, 2017: Physical Chemistry Chemical Physics: PCCP
Verena Pfeifer, Travis E Jones, Sabine Wrabetz, Cyriac Massué, Juan J Velasco Vélez, Rosa Arrigo, Michael Scherzer, Simone Piccinin, Michael Hävecker, Axel Knop-Gericke, Robert Schlögl
Tremendous effort has been devoted towards elucidating the fundamental reasons for the higher activity of hydrated amorphous Ir(III/IV) oxyhydroxides (IrO x ) in the oxygen evolution reaction (OER) in comparison with their crystalline counterpart, rutile-type IrO2, by focusing on the metal oxidation state. Here we demonstrate that, through an analogy to photosystem II, the nature of this reactive species is not solely a property of the metal but is intimately tied to the electronic structure of oxygen. We use a combination of synchrotron-based X-ray photoemission and absorption spectroscopies, ab initio calculations, and microcalorimetry to show that holes in the O 2p states in amorphous IrO x give rise to a weakly bound oxygen that is extremely susceptible to nucleophilic attack, reacting stoichiometrically with CO already at room temperature...
November 18, 2016: Chemical Science
Muhammad Afzal Javed, Siddhartha Biswas, Leslie G Willis, Stephanie Harris, Caitlin Pritchard, Monique M van Oers, B Cameron Donly, Martin A Erlandson, Dwayne D Hegedus, David A Theilmann
: Baculovirus occlusion derived virus (ODV) initiate infection of lepidopteran larval hosts by binding to the midgut epithelia which is mediated by per os infectivity factors (PIFs). Autographa californica multiple nucleopolyhedrovirus (AcMNPV) encodes seven PIF proteins of which PIF1-4 form a core complex in ODV envelopes to which PIF0 and PIF6 loosely associate. Deletion of any pif results in ODV unable to bind or enter midgut cells. AC83 also associates with the PIF complex and this study further analyzed its role in oral infectivity to determine if it is a PIF protein...
December 28, 2016: Journal of Virology
Jos A H van Oers, Maarten W Nijsten, Armand R Girbes
No abstract text is available yet for this article.
January 1, 2017: JAMA Internal Medicine
Lea Den Broeder, Jeroen Devilee, Hans Van Oers, A Jantine Schuit, Annemarie Wagemakers
Community engagement in public health policy is easier said than done. One reason is that public health policy is produced in a complex process resulting in policies that may appear not to link up to citizen perspectives. We therefore address the central question as to whether citizen engagement in knowledge production could enable inclusive health policy making. Building on non-health work fields, we describe different types of citizen engagement in scientific research, or 'Citizen Science'. We describe the challenges that Citizen Science poses for public health, and how these could be addressed...
December 23, 2016: Health Promotion International
Tao Zhang, Shuai-Chen Li, Wei Zhu, Zhi-Ping Zhang, Jun Gu, Ya-Wen Zhang
For the first time, shape-tunable Pt-Ir alloy nanocatalysts including both single-crystalline (nano-octahedra (NOs), nano-truncated octahedra (NTOs), nanocubes (NCs)) and polycrystalline (nanocluster flowers (NCFs), nanowires (NWs), nano-short-chains (NSCs), and nano-octahedral stars (NOSs)) ones were synthesized with a facile one-pot solvothermal method, via precise control of the facet-selective agents (Br(-) and I(-)). The surface effects of Pt-Ir alloy nanocatalysts for oxygen electrode reaction in acidic solution were intensively investigated...
December 23, 2016: Nanoscale
Ali Han, Hanyu Zhang, Ruihan Yuan, Hengxing Ji, Pingwu Du
Hydrogen is essential to many industrial processes and could play an important role as an ideal clean energy carrier for future energy supply. Herein, we report for the first time the growth of crystalline Cu3P phosphide nanosheets on conductive nickel foam (Cu3P@NF) for electrocatalytic and visible light-driven overall water splitting. Our results show that the Cu3P@NF electrode can be used as an efficient Janus catalyst for both the oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER)...
January 9, 2017: ACS Applied Materials & Interfaces
Paul A DeSario, Christopher N Chervin, Eric S Nelson, Megan B Sassin, Debra R Rolison
Using a solution-based, non-line-of sight synthesis, we electrolessly deposit ultrathin films of RuO2 ("nanoskins") on planar and 3D substrates and benchmark their activity and stability for oxygen-evolution reaction (OER) in acid electrolyte under device-relevant conditions. When an electrically contiguous ∼9 nm thick RuO2 nanoskin is expressed on commercially available, insulating SiO2 fiber paper, the RuO2@SiO2 electrode exhibits high current density at low overpotential (10 mA cm(-2) @ η = 280 mV), courtesy of a catalyst amplified in 3D; however, the mass-normalized activity falls short of that achieved for films deposited on planar, metallic substrates (Ti foil)...
January 9, 2017: ACS Applied Materials & Interfaces
Naveen Chandrasekaran, Saravanakumar Muthusamy
We report the synthesis of lightweight, free-standing Ni-Fe@rGO porous interconnects by carbothermal reduction of Ni-FeOx using graphene oxide (GO) as the reducing agent. Here, we take advantage of the oxygen functionalities present in GO to aid in anchoring the metal ions followed by epoxide-assisted Ni-FeOx@GO network formation. When pyrolyzed under inert conditions, Ni-FeOx@GO networks were converted to Ni-Fe@rGO by simple carbothermal metal reduction at 800 °C. The Ni-Fe@rGO monoliths were found to be macroporous, electrically conducting, and electrocatalytic toward oxygen evolution reaction (OER)...
December 22, 2016: Langmuir: the ACS Journal of Surfaces and Colloids
Sambhaji S Shinde, Chi-Ho Lee, Abdul Sami, Dong-Hyung Kim, Sang-Uck Lee, Jung-Ho Lee
Rational design of efficient and durable bifunctional oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) electrocatalysts is critical for rechargeable metal-air batteries. Here, we developed a facile strategy for fabricating three-dimensional phosphorus and sulfur codoped carbon nitride sponges sandwiched with carbon nanocrystals (P,S-CNS). These materials exhibited high surface area and superior ORR and OER bifunctional catalytic activities than those of Pt/C and RuO2, respectively, concerning its limiting current density and onset potential...
December 27, 2016: ACS Nano
Peng Fei Liu, Shuang Yang, Bo Zhang, Hua Gui Yang
Efficient and durable electrocatalysts from earth-abundant elements play a vital role in the key renewable energy technologies including overall water splitting and hydrogen fuel cells. Here, generally used CoFe based layered double hydroxides (LDHs) were first delaminated and exfoliated in the DMF-ethanol solvent (CoFe LDH-F), with enhancement both in oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). The exfoliation process creates more coordinatively unsaturated metals and improves the intrinsic electronic conductivity, which is important in water electrolyzer reactions...
December 21, 2016: ACS Applied Materials & Interfaces
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