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Yu Li, Shuangming Chen, Dawei Xi, Yanan Bo, Ran Long, Chengming Wang, Li Song, Yujie Xiong
The electrocatalytic oxygen evolution reaction (OER) is a highly important reaction that requires a relatively high overpotential and determines the rate of water splitting-a process for producing hydrogen. The overall OER performance is often largely limited by uncontrollable interface when active catalysts are loaded on conductive supports, for which polymer binders are widely used, but inevitably block species transportation channels. Here, a scalable fabrication approach to freestanding graphitized carbon nanofiber networks is reported, which provides abundant sites for in situ growing Fe/Ni catalysts with the improved interface...
November 17, 2017: Small
Wei Sun, Zhenhua Zhou, Waqas Qamar Zaman, Li-Mei Cao, Ji Yang
Developing more efficient and stable oxygen evolution reaction (OER) catalysts is critical for future energy conversion and storage technologies. We demonstrate that inducing a lattice strain in IrO2 crystal structure due to interface lattice mismatch enables an enhancement of the OER catalytic activity. The lattice strain is obtained by the direct growth of IrO2 nanoparticles on a specially exposed surface of α-MnO2 nanorods via a simple two-step hydrothermal synthesis. Interestingly, the prepared hydride OER activity increases with a lower IrO2 grown mass, which offers an opportunity to reduce the usage of precious iridium and ultimately obtains a specific mass activity of 3...
November 17, 2017: ACS Applied Materials & Interfaces
Xueqing Zhang, Chonglong Cao, Anja Bieberle-Hütter
The structures of transition metal surfaces and metal oxides are commonly believed to have a significant effect on the catalytic reactions. Density functional theory calculations are therefore used in this study to investigate the oxygen evolution reaction (OER) over nanostructured, i.e. nanocluster and nanocavity, surfaces of hematite (Fe2O3). The calculated results demonstrate an optimum nanocluster size with respect to the OER overpotential. The presence of nanoclusters on the electrode is regarded as an attractive strategy for increasing the activity in photoelectrochemical water splitting...
November 17, 2017: Physical Chemistry Chemical Physics: PCCP
Yue Han, Stineke van Houte, Monique M van Oers, Vera I D Ros
Host behavioural manipulation is a common strategy used by parasites to enhance their survival and/or transmission. Baculoviruses induce hyperactivity and tree-top disease (pre-death climbing behaviour) in their caterpillar hosts. However, little is known about the underlying mechanisms of this behavioural manipulation. A previous study showed that the baculovirus Spodoptera exigua multiple nucleopolyhedrovirus (SeMNPV) induced tree-top disease at 3 days post infection in third instar S. exigua larvae and that light plays a key role in triggering this behaviour...
November 16, 2017: Parasitology
Zhu Chen, Coleman X Kronawitter, Xiaofang Yang, Yao-Wen Yeh, Nan Yao, Bruce E Koel
A new catalyst is presented for the oxygen evolution reaction (OER) based on cerium-modified copper oxide (CuOx) prepared using a facile electrodeposition procedure. Incorporation of Ce into CuOx leads to greatly improved OER activity, which reached an optimal value at a surface concentration of 6.9 at% Ce. Specifically, the OER current density at 400 mV overpotential for the most active Ce-modified CuOx catalyst (6.9 at% Ce) was 3.3 times greater compared to the pure CuOx. Coincident with the improved OER activity, Ce incorporation also leads to significant structural changes that manifested in increasing degrees of disorder...
November 14, 2017: Physical Chemistry Chemical Physics: PCCP
Bob Boogaard, Jan W M van Lent, David A Theilmann, Martin A Erlandson, Monique M van Oers
Baculoviruses orally infect caterpillars in the form of occlusion-derived viruses (ODVs). The ODV-envelope contains a number of proteins which are essential for oral infectivity, called per os infectivity factors (PIFs). Most of these PIFs are involved in the formation of an ODV-entry complex that consists of a stable core, formed by PIF1, PIF2, PIF3 and PIF4, and the more loosely associated PIFs P74 (PIF0) and P95 (PIF8). PIF1, PIF2 and PIF3 are essential for formation of the stable core, whereas deletion of the pif4 gene results in the formation of a smaller complex...
November 14, 2017: Journal of General Virology
Taejung Lim, Moonchang Sung, Jongwon Kim
Nanoporous electrodes have received great attention because of their unique electrochemical properties. Here, the electrocatalytic oxygen evolution reaction (OER) activities at porous Pt layers with pore dimensions in the microporous range were examined. The OER activity of the porous Pt layers in acidic media increased as the porosity of the Pt layers increased, and the highest OER activity possessed an overpotential that was 270 mV lower than that of a bulk flat electrode. The porous Pt layers did not exhibit electrocatalytic enhancement for OER in basic media, wherein the surface area of the pores was not utilized for OER...
November 13, 2017: Scientific Reports
Hengjie Liu, Qun He, Hongliang Jiang, Yunxiang Lin, Youkui Zhang, Muhammad Habib, Shuangming Chen, Li Song
Developing highly active and low-cost heterogeneous catalysts towards overall electrochemical water splitting is extremely desirable but still a challenge. Herein, we report pyrite NiS2 nanosheets doped with vanadium heteroatoms as bifunctional electrode materials for both hydrogen- and oxygen-evolution reaction (HER and OER). Notably, the electronic structure reconfiguration of pyrite NiS2 is observed from typical semiconductive characteristics to metallic characteristics by engineering vanadium (V) displacement defect, which is confirmed by both experimental temperature-dependent resistivity and theoretical density functional theory (DFT) calculations...
November 13, 2017: ACS Nano
Tan Huang, Yu Chen, Jong-Min Lee
Developing highly efficient electrocatalysts for oxygen evolution is vital for renewable and sustainable energy production and storage. Herein, nitrogen-doped carbon encapsulated CoOx-MoC heterostructures are reported for the first time as high performance oxygen evolution electrocatalysts. The composition can be tuned by the addition of a Mo source to form a nanowire-assembled hierarchically porous microstructure, which can enlarge the specific surface area, thus exposing more active sites, facilitating mass transport and charge transfer...
November 9, 2017: Small
Ashwani Kumar, Sayan Bhattacharyya
Electrocatalytic water-splitting, a combination of oxygen and hydrogen evolution reactions (OER and HER), is highly attractive in clean energy technologies, especially for high-purity hydrogen production, whereas developing stable, earth-abundant, bifunctional catalysts has continued to pose major challenges. Herein, a mesoporous NiFe-oxide nanocube (NiFe-NC) system is developed from a NiFe Prussian blue analog metal-organic framework as an efficient bifunctional catalyst for overall water-splitting. The NiFe-NCs with ∼200 nm side length have a Ni/Fe molar ratio of 3:2 and is a composite of NiO and α/γ-Fe2O3...
November 17, 2017: ACS Applied Materials & Interfaces
Helmut Schäfer, Karsten Küpper, Klaus Müller-Buschbaum, Diemo Daum, Martin Steinhart, Joachim Wollschläger, Ulrich Krupp, Mercedes Schmidt, Weijia Han, Johannes Stangl
The use of proton exchange membrane (PEM) electrolyzers is the method of choice for the conversion of solar energy when frequently occurring changes of the current load are an issue. However, this technique requires electrolytes with low pH. All oxygen evolving electrodes working durably and actively in acids contain IrOx. Due to their scarcity and high acquisition costs, noble elements like Pt, Ru and Ir need to be replaced by earth abundant elements. We have evaluated a cobalt containing steel for use as an oxygen-forming electrode in H2SO4...
November 8, 2017: Nanoscale
Yun-Pei Zhu, Jingrun Ran, Shi-Zhang Qiao
Developing efficient electrocatalysts consisting of earth-abundant elements for oxygen evolution reaction (OER) is crucial for energy devices and technologies. Herein, we report self-supported highly porous nitrogen-doped graphene foam synthesized through the electrochemical expansion of carbon-fiber paper and subsequent nitrogen plasma treatment. A thorough characterization, such as electron microscopy and synchrotron-based near-edge X-ray absorption fine structure, indicates the well-developed porous structures featuring homogeneously doped nitrogen heteroatoms...
November 17, 2017: ACS Applied Materials & Interfaces
Zhaoxi Yang, Jun-Ye Zhang, Zaiyong Liu, Zhishan Li, Lin Lv, Xiang Ao, Yifan Tian, Yi Zhang, Jianjun Jiang, Chundong Wang
Electrocatalysts with outstanding performance have been highly desired toward exploration of new energy storage and conversion devices/systems as well as making an efficient and eco-friendly utilization of green energy. In this study, we composed an iron-based binary diselenide-derived oxide (Fe-SDO) with a facile one-step hydrothermal method to utilize the earth-abundant iron and the probably prosperous catalytic performance of metal-selenides compounds. The catalyst exhibits an overpotential of 226 mV at a current density of 10 mA/cm(2), a Tafel slope of 41 mV dec(-1), and robust durability after catalyzing vigorous OER for 36 h constantly...
November 13, 2017: ACS Applied Materials & Interfaces
Huayu Chen, Shuxin Ouyang, Ming Zhao, Yunxiang Li, Jinhua Ye
Water splitting has been greatly limited by the sluggish kinetics of the oxygen evolution reaction (OER). High-oxidation-state metal species are required as the favorable active sites in OER. Here, amorphous Cox-Fe-B (x is the molar ratio of Co/Fe), Co-B, and Fe-B compounds were successfully synthesized as the oxygen evolution electrocatalysts. The calculation of turnover frequency (TOF) indicates that both the Co and Fe sites are active for OER. Cyclic voltammetry, X-ray photoelectron spectroscopy, and long-term stability curves were used to demonstrate that Fe can stabilize Co in a higher oxidation level and meanwhile promote the generation of OOH-like species (the key intermediates for OER)...
November 13, 2017: ACS Applied Materials & Interfaces
Dong Un Lee, Moon Gyu Park, Zachary Paul Cano, Wook Ahn, Zhongwei Chen
Nano-engineered hierarchical core-shell chestnut-like structures have been successfully synthesized as a bi-functionally active electrocatalyst for rechargeable metal-air battery applications. Both the morphology and composition of the catalyst have been optimized by the facile hydrothermal reaction, resulting in the 10-hour treated sample to perform significantly enhanced activity towards facilitating both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Specifically, the catalyst demonstrated -0...
November 5, 2017: ChemSusChem
Qin Liu, Lisi Xie, Zhiang Liu, Gu Du, Abdullah M Asiri, Xuping Sun
It is of high importance to design efficient electrocatalysts for the oxygen evolution reaction (OER) at alkaline pH. In this communication, we report the development of a Zn-doped Ni3S2 nanosheet array on Ni foam (Zn-Ni3S2/NF) as a high-performance and durable electrocatalyst for the OER. Such Zn-Ni3S2/NF drives a catalytic current density of 100 mA cm(-2) with the requirement of an OER overpotential of 330 mV, 90 mV less than that for Ni3S2/NF. Furthermore, Zn-Ni3S2/NF demonstrates excellent long-term electrochemical durability maintaining its activity at an overpotential of 300 mV for 20 h...
November 16, 2017: Chemical Communications: Chem Comm
Mengke Zhai, Fei Wang, Hongbin Du
The preparation of highly active, sustainable, nonprecious metal materials as hydrogen evolution and oxygen evolution reaction (HER and OER) catalysts that can relieve the environmental pollution and energy shortage problems present a great challenge to chemists. We herein report the fabrication of a highly active metal phosphide-carbon composite catalyst for HER and OER in acid and basic solution, respectively. The catalyst is derived through carbonization and subsequent phosphorization of two-dimensional (2D) cobalt porphyrinic metal-organic framework nanosheets...
November 13, 2017: ACS Applied Materials & Interfaces
Ling Wang, Xiaolei Huang, Songshan Jiang, Meng Li, Kai Zhang, Ying Yan, Huiping Zhang, Jun Min Xue
Water electrolysis has been considered as one of the most efficient approaches to produce renewable energy, although efficient removal of gas bubbles during the process is still challenging, which has been proved to be critical and can further promote electrocatalytic water splitting. Herein, a novel strategy is developed to increase gas bubble escape rate for water splitting by using nonwoven stainless steel fabrics (NWSSFs) as the conductive substrate decorated with flakelike iron nickel-layered double hydroxide (FeNi LDH) nanostructures...
November 13, 2017: ACS Applied Materials & Interfaces
Chen Zhang, Yingfeng Xu, Ping Lu, Xiaohua Zhang, FangFang Xu, Jianlin Shi
A significant overpotential necessary for the electrochemical oxygen evolution reaction (OER) is one of the most serious disad-vantages in water electrolysis, which, on the contrary, gives the probability to electrochemically produce ozone alternative to the common corona discharge. To effectively suppress the competitive OER and improve gaseous ozone escaping, here, we present a capillary effect-enabled electrolysis strategy by employing an unusual partial-submersed mode of anode composed of a β-PbO2 cuboids-loaded bulk porous Pb, and realize a much enhanced electrocatalytic gaseous ozone production in comparison to the cases of solid Pb counterpart and/or usual submersion operation...
November 2, 2017: Journal of the American Chemical Society
Yang Wang, Timothy Williams, Thomas Gengenbach, Biao Kong, Dongyuan Zhao, Huanting Wang, Cordelia Selomulya
We successfully synthesized a novel electro-catalyst with a unique structure of Ni2P nanoparticles decorating the surface of MoO2@MoS2 sub-microwires on titanium foil (denote as NiMoO-SP/Ti) via a facile temperature-programmed sulfuration-phosphorization from its nickel molybdate precursor. The metallic MoO2 core facilitates electron transfer, and the interfaces between MoS2 nanosheets and Ni2P nanoparticles enhance catalytic activity both for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER)...
November 16, 2017: Nanoscale
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