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oxygen evolution

Samar Kumar Das, Suranjana Bose, Joyashish Debgupta, Rani Ramsundar
The design and synthesis of an efficient and robust water oxidation catalyst (WOC) with inexpensive materials remain an important challenge in the context of 'artificial photosynthesis'. Herein, we report a simple but unique technique to generate in situ a thin-film of α-Co(OH)2 on the surface of zeolite-Y [hereafter named as Y-α-Co(OH)2] that acts as an efficient and stable catalyst for electrochemical water oxidation in an alkaline pH. Catalyst Y-α-Co(OH)2 is so stable that it retains its catalytic activity even after 2000 cyclic voltammetric cycles of water oxidation...
April 21, 2017: Chemistry: a European Journal
Alexis Grimaud, Oscar Diaz-Morales, Binghong Han, Wesley T Hong, Yueh-Lin Lee, Livia Giordano, Kelsey A Stoerzinger, Marc T M Koper, Yang Shao-Horn
Understanding how materials that catalyse the oxygen evolution reaction (OER) function is essential for the development of efficient energy-storage technologies. The traditional understanding of the OER mechanism on metal oxides involves four concerted proton-electron transfer steps on metal-ion centres at their surface and product oxygen molecules derived from water. Here, using in situ (18)O isotope labelling mass spectrometry, we provide direct experimental evidence that the O2 generated during the OER on some highly active oxides can come from lattice oxygen...
May 2017: Nature Chemistry
Dehua Xiong, Qingqing Zhang, Sitaramanjaneya Mouli Thalluri, Junyuan Xu, Wei Li, Xiuli Fu, Lifeng Liu
We report a very easy and cost-effective approach to the fabrication of monolithic Co9S8 water oxidation electrodes (Co@Co9S8), which is fabricated by one-step hydrothermal treatment of commercially available cobalt foam in the presence of thiourea. The morphology, crystal structure, microstructure, and composition of as-fabricated Co@Co9S8 electrodes are examined using scanning electron microscopy (SEM), powder X-ray diffraction (XRD), transmission electron microscope (TEM), and X-ray photoelectron spectroscopy (XPS), and their electrochemical properties are investigated by cyclic voltammetry (CV), chronopotentiometry (CP), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS)...
April 21, 2017: Chemistry: a European Journal
Yanyong Wang, Yiqiong Zhang, Zhijuan Liu, Chao Xie, Shi Feng, Dongdong Liu, Mingfei Shao, Shuangyin Wang
Layered double hydroxides (LDHs) with two-dimensional lamellar structures show excellent electrocatalytic properties. However, the catalytic activity of LDHs needs to be further improved as the large lateral size and thickness of the bulk material limit the number of exposed active sites. However, the development of efficient strategies to exfoliate bulk LDHs into stable monolayer LDH nanosheets with more exposed active sites is very challenging. On the other hand, the intrinsic activity of monolayer LDH nanosheets can be tuned by surface engineering...
April 21, 2017: Angewandte Chemie
M Coduri, M Scavini, M Pani, M M Carnasciali, H Klein, C Artini
The evolution of the defect structure and microstructure of heavily Gd-doped ceria (Ce1-μREμO2-y, 0.313 ≤ μ ≤ 0.438) for different synthetic pathways is investigated here to explore the way defects interact with each other in a composition range known to effectively hamper the application of the material as an electrolyte. Synchrotron radiation powder diffraction is exploited by combining conventional Rietveld analysis with the Pair Distribution Function to get a multiscale picture of defect structures, and it is combined with Raman spectroscopy to assess local scale interactions...
April 21, 2017: Physical Chemistry Chemical Physics: PCCP
David Monnin, Natacha Kremer, Emmanuel Desouhant, Fabrice Vavre
The oxidative homeostasis is the balance between reactive oxygen species and antioxidant molecules. In addition to be considered as a key factor underlying life-history traits evolution, the oxidative homeostasis has been shown to be involved in many host-symbiont associations. Previous studies suggest an interaction between the bacterial endosymbiont Wolbachia and the oxidative homeostasis of some insect hosts. This interaction is likely to exert a strong influence on the host evolution, as it has been proposed in the wasp Asobara tabida, whose dependence upon Wolbachia is due to the evolutionary loss of its ability to regulate the oxidative homeostasis in the absence of the symbiont...
2017: PloS One
Wan Li, Shilin Zhang, Qining Fan, Fazhi Zhang, Sailong Xu
Transition metal phosphide (TMP) nanostructures have stimulated increasing interest for use in water splitting owing to their abundant natural sources and high activity for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Typically, the preparation of hierarchical TMPs involves the utilization of expensive or dangerous phosphorus sources, and, in particular, the understanding of topotactic transformations of the precursors to crystalline phases-which could be utilized to enhance electrocatalytic performance-remains very limited...
April 20, 2017: Nanoscale
Hui Chen, Ren-Cun Jin
The anaerobic ammonium oxidation (anammox) process is a promising wastewater treatment method for biological nitrogen removal. A sufficient amount of active anammox sludge as a seed is crucial to the fast establishment and stability of the anammox process. Anammox bacteria is a kind of microorganism which is sensitive to the environmental conditions, e.g., oxygen, temperature. The optimum temperature and pH for the growth of the anammox bacteria are 30-40 °C and 6.7-8.3. A proper preservation technique allows fast start-up of the anammox process, overcoming the long doubling time of anammox biomass...
April 19, 2017: Applied Microbiology and Biotechnology
Hui-Wen Lin, Caroline Kustermans, Eleni Vaiopoulou, Antonin Prévoteau, Korneel Rabaey, Zhiguo Yuan, Ilje Pikaar
The addition of iron salts is one of the most commonly used dosing strategies for sulfide control in sewers. However, iron salts decrease the sewage pH which not only reduces the effectiveness of sulfide precipitation but also enhances the release of residual sulfide to the sewer atmosphere. Equally important, concentrated iron salt solutions are corrosive and their frequent transport, handling, and on-site storage often come with Occupational Health and Safety (OH&S) concerns. Here, we experimentally demonstrated a novel sulfide control approach using electrochemical systems with parallel placed iron electrodes...
April 15, 2017: Water Research
Christopher T Reinhard, Stephanie L Olson, Edward W Schwieterman, Timothy W Lyons
Ocean-atmosphere chemistry on Earth has undergone dramatic evolutionary changes throughout its long history, with potentially significant ramifications for the emergence and long-term stability of atmospheric biosignatures. Though a great deal of work has centered on refining our understanding of false positives for remote life detection, much less attention has been paid to the possibility of false negatives, that is, cryptic biospheres that are widespread and active on a planet's surface but are ultimately undetectable or difficult to detect in the composition of a planet's atmosphere...
April 2017: Astrobiology
Ruixiang Ge, Hongbin Du, Kai Tao, Qiuju Zhang, Liang Chen
The development of non-noble metal oxygen evolution electrocatalysts working efficiently under benign conditions is still urgent and challenging. Herein we report the electrochemical generation of novel cobalt-borate (Co-Bi) nanoarray on carbon cloth (Co-Bi NA/CC) from CoS2 nanoarray precursor. As an integrated three-dimensional electrode, such Co-Bi NA/CC exhibits excellent catalytic performance for oxygen evolution with 10 mA cm-2 at an overpotential of 411 mV. Notably, this electrode also demonstrates outstanding long-term electrochemical durability for at least 20 hours, implying the great potential for water splitting applications at near-neutral pH...
April 18, 2017: ACS Applied Materials & Interfaces
Zhiyi Lu, Guangxu Chen, Yanbin Li, Haotian Wang, Jin Xie, Lei Liao, Chong Liu, Yayuan Liu, Tong Wu, Yuzhang Li, Alan C Luntz, Michal Bajdich, Yi Cui
Identification of active sites for catalytic processes has both fundamental and technological implications for rational design of future catalysts. Herein, we study the active surfaces of layered lithium cobalt oxide (LCO) for the oxygen evolution reaction (OER) using the enhancement effect of electrochemical delithiation (De-LCO). Our theoretical results indicate that the most stable (0001) surface has a very large overpotential for OER independent of lithium content. In contrast, edge sites such as the nonpolar (112̅0) and polar (011̅2) surfaces are predicted to be highly active and dependent on (de)lithiation...
April 21, 2017: Journal of the American Chemical Society
David Cooper, Christoph Baeumer, Nicolas Bernier, Astrid Marchewka, Camilla La Torre, Rafal E Dunin-Borkowski, Stephan Menzel, Rainer Waser, Regina Dittmann
The control and rational design of redox-based memristive devices, which are highly attractive candidates for next-generation nonvolatile memory and logic applications, is complicated by competing and poorly understood switching mechanisms, which can result in two coexisting resistance hystereses that have opposite voltage polarity. These competing processes can be defined as regular and anomalous resistive switching. Despite significant characterization efforts, the complex nanoscale redox processes that drive anomalous resistive switching and their implications for current transport remain poorly understood...
April 18, 2017: Advanced Materials
Siegfried Aigner, Andreas Holzinger, Ulf Karsten, Ilse Kranner
Batrachospermum turfosum Bory is one of the generalists among the few red algae that have adapted to freshwater habitats, occurring in a variety of primarily shaded, nutrient-poor micro-habitats with lotic (running) or lentic (standing) waters. Seasonal variations in water level and canopy cover can expose this sessile alga to widely fluctuating temperatures, solar irradiation and nutrient availability. Here we report on the ecophysiology of B. turfosum collected from an ultra-oligotrophic bog pool in the Austrian Alps...
2017: Phycologia
Jan Luxa, Vlastimil Mazánek, Martin Pumera, Petr Lazar, David Sedmidubsky, Mauro Callisti, Tomas Polcar, Zdenek Sofer
Tremendous attention is paid to renewable sources of energy. Transition metal dichalcogenides (TMDs) are intensively studied for their promising catalytic activities in hydrogen evolution reaction (HER) and oxygen reduction reaction (ORR). In this fundamental work, we explore the catalytic properties of TMDs family members: 2H TaS2 and 1T TaS2. Our findings reveal that both polytypes exhibit poor HER performance which is even more pronounced when subjected to electrochemical treatment with reduction/oxidation...
April 13, 2017: Chemistry: a European Journal
Zhanjun Guo, Bridgette A Barry
A redox-active tyrosine, YZ (Y161 in the D1 polypeptide), is essential in photosystem II (PSII), which conducts photosynthetic oxygen evolution. On each step of the light-driven oxygen evolving reaction, YZ radical is formed by a chlorophyll cation radical. YZ radical is then reduced by a Mn4CaO5 cluster in a proton coupled electron transfer (PCET) reaction. YZ is hydrogen bonded to His190-D1 and to water molecules in a hydrogen-bonding network, involving calcium. This network is sensitive to disruption with ammonia and to removal and replacement of calcium...
April 14, 2017: Journal of Physical Chemistry. B
Angel T Garcia-Esparza, Tatsuya Shinagawa, Samy Ould-Chikh, Muhammad Qureshi, Xuyuan Peng, Nini Wei, Dalaver H Anjum, Alain Clo, Tsu-Chien Weng, Dennis Nordlund, Dimosthenis Sokaras, Jun Kubota, Kazunari Domen, Kazuhiro Takanabe
For overall water-splitting systems, it is essential to establish O2 -insensitive cathodes that allow cogeneration of H2 and O2 . An acid-tolerant electrocatalyst is described, which employs a Mo-coating on a metal surface to achieve selective H2 evolution in the presence of O2 . In operando X-ray absorption spectroscopy identified reduced Pt covered with an amorphous molybdenum oxyhydroxide hydrate with a local structural order composed of polyanionic trimeric units of molybdenum(IV). The Mo layer likely hinders O2 gas permeation, impeding contact with active Pt...
April 13, 2017: Angewandte Chemie
Xueping Zhang, Liang Huang, Yujie Han, Miao Xu, Shaojun Dong
Developing efficient and earth-abundant oxygen evolution reaction (OER) electrocatalysts is of great importance in renewable energy research. Herein, we report nitrogen-doped carbon encapsulating γ-MoC/Ni heterostructures (γ-MoC/Ni@NC) for the first time as efficient OER electrocatalysts. The composites can be controlled by the addition of a Mo source to form a nanoparticle-assembled hierarchically porous nanostructure, which can enlarge the specific surface area, thus exposing more active sites. Moreover, we demonstrate that the formation of γ-MoC@Ni heterostructures and the resulting synergistic effect between γ-MoC and Ni can facilitate the reaction kinetics, leading to significantly improved OER activity with an onset overpotential of merely 240 mV, and a low overpotential of 310 mV to afford a current density of 10 mA cm(-2)...
April 13, 2017: Nanoscale
Seung Hyo Noh, Choah Kwon, Jeemin Hwang, Takeo Ohsaka, Beom-Jun Kim, Tae-Young Kim, Young-Gi Yoon, Zhongwei Chen, Min Ho Seo, Byungchan Han
In this study, we report self-assembled nitrogen-doped fullerenes (N-fullerene) as non-precious catalysts, which are active for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), and thus applicable for energy conversion and storage devices such as fuel cells and metal-air battery systems. We screen the best N-fullerene catalyst at the nitrogen doping level of 10 at%, not at the previously known doping level of 5 or 20 at% for graphene. We identify that the compressive surface strain induced by doped nitrogen plays a key role in the fine-tuning of catalytic activity...
April 13, 2017: Nanoscale
Wenbo Shi, Jinjing Li, Erik S Polsen, C Ryan Oliver, Yikun Zhao, Eric R Meshot, Michael Barclay, D Howard Fairbrother, A John Hart, Desiree L Plata
A lack of synthetic control and reproducibility during vertically aligned carbon nanotube (CNT) synthesis has stifled many promising applications of organic nanomaterials. Oxygen-containing species are particularly precarious in that they have both beneficial and deleterious effects and are notoriously difficult to control. Here, we demonstrated diatomic oxygen's ability, independent of water, to tune oxide-supported catalyst thin film dewetting and influence nanoscale (diameter and wall number) and macro-scale (alignment and density) properties for as-grown vertically aligned CNTs...
April 20, 2017: Nanoscale
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