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Chaoran Jiang, Savio J A Moniz, Aiqin Wang, Tao Zhang, Junwang Tang
It is widely accepted within the community that to achieve a sustainable society with an energy mix primarily based on solar energy we need an efficient strategy to convert and store sunlight into chemical fuels. A photoelectrochemical (PEC) device would therefore play a key role in offering the possibility of carbon-neutral solar fuel production through artificial photosynthesis. The past five years have seen a surge in the development of promising semiconductor materials. In addition, low-cost earth-abundant co-catalysts are ubiquitous in their employment in water splitting cells due to the sluggish kinetics of the oxygen evolution reaction (OER)...
June 23, 2017: Chemical Society Reviews
Natav Yatom, Yuval Elbaz, Shelly Navon, Maytal Caspary Toroker
Hematite's (α-Fe2O3) major limitation to efficiently splitting water using sunlight is the low rate of the oxygen evolution reaction (OER). Thus, identifying the OER rate limiting step is a cornerstone to enhancing the current under low applied potential. Different measurement techniques showed similar absorption difference spectra during a change in applied potential on the hematite anode below and above the onset of the OER in the dark and under light. This absorption change was shown to result from surface modification during the OER, but the specific surface species could not be resolved...
June 22, 2017: Physical Chemistry Chemical Physics: PCCP
Fei Hu, Shengli Zhu, Shuangming Chen, Yu Li, Lu Ma, Tianpin Wu, Yan Zhang, Chengming Wang, Congcong Liu, Xianjin Yang, Li Song, Xiaowei Yang, Yujie Xiong
The intrinsic catalytic activity at 10 mA cm(-2) for oxygen evolution reaction (OER) is currently working out at overpotentials higher than 320 mV. A highly efficient electrocatalyst should possess both active sites and high conductivity; however, the loading of powder catalysts on electrodes may often suffer from the large resistance between catalysts and current collectors. This work reports a class of bulk amorphous NiFeP materials with metallic bonds from the viewpoint of electrode design. The materials reported here perfectly combine high macroscopic conductivity with surface active sites, and can be directly used as the electrodes with active sites toward high OER activity in both alkaline and acidic electrolytes...
June 22, 2017: Advanced Materials
Alexander T Baugh, Sarah C Davidson, Michaela Hau, Kees van Oers
Variation in the reactivity of the endocrine stress axis is thought to underlie aspects of persistent individual differences in behavior (i.e. animal personality). Previous studies, however, have focused largely on estimating baseline or peak levels of glucocorticoids (CORT), often in captive animals. In contrast, the temporal dynamics of the HPA axis-how quickly it turns on and off, for example-may better indicate how an individual copes with stressors. Moreover, these HPA components might be correlated, thereby representing endocrine suites...
June 19, 2017: General and Comparative Endocrinology
Jesse S Ko, Christopher N Chervin, Mallory N Vila, Paul A DeSario, Joseph F Parker, Jeffrey W Long, Debra R Rolison
Electrocatalysis of the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) was assessed for a series of Ni-substituted ferrites (NiyFe1-yOx, where y = 0.1 to 0.9) as expressed in porous, high-surface-area forms (ambigel and aerogel nanoarchitectures). We then correlate electrocatalytic activity with Ni:Fe stoichiometry as a function of surface area, crystallite size, and free volume. In order to ensure in-series comparisons, calcination at 350 °C/air was necessary to crystallize the respective NiyFe1-yOx nanoarchitectures, which index to the inverse spinel structure for Fe-rich materials (y ≤ 0...
June 19, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Shaohong Liu, Zhiyu Wang, Si Zhou, Fengjiao Yu, Mengzhou Yu, Chang-Yang Chiang, Wuzong Zhou, Jijun Zhao, Jieshan Qiu
The oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are cornerstone reactions for many renewable energy technologies. Developing cheap yet durable substitutes of precious-metal catalysts, especially the bifunctional electrocatalysts with high activity for both ORR and OER reactions and their streamlined coupling process, are highly desirable to reduce the processing cost and complexity of renewable energy systems. Here, a facile strategy is reported for synthesizing double-shelled hybrid nanocages with outer shells of Co-N-doped graphitic carbon (Co-NGC) and inner shells of N-doped microporous carbon (NC) by templating against core-shell metal-organic frameworks...
June 19, 2017: Advanced Materials
Si Zhou, Nanshu Liu, Zhiyu Wang, Jijun Zhao
Composites of transition metal and carbon based materials are promising bifunctional catalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), and are widely used in rechargeable metal-air batteries. However, the mechanism of their enhanced bi-catalytic activities remains elusive. Herein we construct N-doped graphene supported by Co(111) and Fe(110) substrates as bifunctional catalysts for ORR and OER in alkaline media. First-principles calculations show that these heterostructures possess a large number of active sites for ORR and OER with overpotentials comparable to those of noble metal benchmark catalysts...
June 16, 2017: ACS Applied Materials & Interfaces
Jan Pieter Marchal, Hedy A van Oers, Heleen Maurice-Stam, Martha A Grootenhuis, A S Paul van Trotsenburg, Lotte Haverman
BACKGROUND: To provide targeted support to parents of children with DS, knowledge of their distress and everyday problems is crucial. For this purpose, psychosocial screening instruments can be a valuable addition to routine clinical practice. AIMS: To determine differences on a psychosocial screener concerning distress and everyday problems in parents of young adolescents (YAs) with DS versus control parents and in mothers of YAs with DS versus fathers. METHODS AND PROCEDURES: We compared outcomes of the Distress Thermometer for Parents in 76 mothers and 44 fathers of 11-13-year-olds with DS versus 64 mothers and 52 fathers of age-matched children without DS (comparing mothers and fathers separately)...
June 12, 2017: Research in Developmental Disabilities
Yu Wang, Xiaoqian Zhao, Yan Zhang, Huijuan Zhang, Li Liu
Up to now, there are rare literatures on Cu2S applied to oxygen evolution reaction (OER) of electro-catalytic field, especially one with specific morphology. In this work,a unique peapod-like Cu2S/C exhibiting superb electrocatalytic performance toward OER is successfully synthesized, by employing the Cu(OH)2 nanorods as template and the nontoxic glucose as the carbon source and annealing with sublimed sulfur ultimately. It can be seen that this work explores a new application area for Cu2S. Precisely, it is the novel morphology that contributes to increasing the electrochemical active surface area effectively and promoting the contact between the Cu2S nanoparticles and the electrolyte...
June 15, 2017: Nanotechnology
Jie Dai, Yinlong Zhu, Yubo Chen, Wei Zhou, Zongping Shao
Electrochemical energy storage and conversion technologies, such as water-splitting devices, rechargeable metal-air batteries, and regenerative fuel cells, are promising alternatives to traditional nonrenewable energy systems. Given the sluggish oxygen evolution reaction (OER) in the above renewable-energy technologies, the development of efficient OER electrocatalysts with high performance is of great importance. Here, we demonstrate a layer-structured oxide Na0.86Co0.95Fe0.05O2 (NCF0.05) as a novel electrocatalyst for efficient water oxidation in alkaline media...
June 21, 2017: ACS Applied Materials & Interfaces
Xin Liang, Bingxia Zheng, Ligang Chen, Juntao Zhang, Zhongbin Zhuang, Biao-Hua Chen
Bimetallic phosphides have attracted research interests for the synergistic effect and superior electrocatalytic activities for electrocatalytic water splitting. Herein, a MOF-derived phosphorization approach was developed to produce Ni2P-CoP bimetallic phosphides as bifunctional electrocatalysts for both hydrogen and oxygen evolution reactions (HER and OER). Ni2P-CoP shows superior electrocatalytic activities to both pure Ni2P and CoP towards HER and OER, revealing a strong synergistic effect. High resolution transmission electron microscopy (HRTEM) and energy dispersive X-ray spectroscopy (EDX) elemental mapping analysis show that in the sample Ni2P-CoP, the Ni2P and CoP nanoparticles with average particle size 10-20 nm were mixed closely in nanoscales, creating numerous Ni2P/CoP interfaces...
June 14, 2017: ACS Applied Materials & Interfaces
Yurui Xue, Zicheng Zuo, Yongjun Li, Huibiao Liu, Yuliang Li
The oxygen evolution reaction (OER), hydrogen evolution reaction (HER), and overall water splitting are major energy and chemical conversion efforts. Progress in electrocatalytic reactions have shown that the future is limitless in many fields. However, it is urgent to develop efficient electrocatalysts. Here, the first graphdiyne-supported efficient and bifunctional electrocatalyst is reported using 3D graphdiyne foam as scaffolds, and NiCo2 S4 nanowires as building blocks (NiCo2 S4 NW/GDF). NiCo2 S4 NW/GDF exhibits outstanding catalytic activity and stability toward both OER and HER, as well as overall water splitting in alkaline media...
June 14, 2017: Small
Jun-Jun Zhang, Hong-Hui Wang, Tian-Jian Zhao, Ke-Xin Zhang, Xiao Wei, Xin-Hao Li, Shin-Ichi Hirano, Jie-Sheng Chen
Oxygen vacancies could help to capture oxygen-containing species and act as active centers for oxygen evolution reaction (OER). Unfortunately, effective methods for generating a rich amount of oxygen vacancies on the surface of various nanocatalysts are rather limited. In this work, we described an effective way to generate oxygen vacancy-rich surface of transition metal oxides, exemplified with Co3O4 here, simply by constructing highly coupled interface of ultra-fine Co3O4 nanocrystals and metallic Ti. Impressively, the amounts of oxygen vacancy on the surface of Ti@Co3O4 far surpassed the reported values of the Co3O4 modified even under highly critical conditions...
June 14, 2017: ChemSusChem
Yu He, Jinfeng Zhang, Guowei He, Xiaopeng Han, Xuerong Zheng, Cheng Zhong, Wenbin Hu, Yida Deng
Two-dimensional (2D) nanocatalysts with a large specific surface area and efficient charge conductivity are promising candidates for catalyzing the sluggish oxygen evolution reaction (OER) and oxygen reduction reaction (ORR), which are at the heart of various electrochemical energy conversion and storage technologies. Here, we report the synthesis of an ultrathin Co3O4 nanofilm with a thickness of nearly 1.8 nm via a surfactant- and template-free facile hydrothermal route. The proposed synthesis strategy can be extended to the preparation of 2D NixCo3-xO4 and FexCo3-xO4 nanostructures...
June 13, 2017: Nanoscale
Jongsik Park, Young Jin Sa, Hionsuck Baik, Taehyun Kwon, Sang Hoon Joo, Kwangyeol Lee
Nanoframe electrocatalysts have attracted great interest due to their inherently high active surface area per a given mass. Although recent progress has enabled the preparation of single nanoframe structures with a variety of morphologies, more complex nanoframe structures such as a double-layered nanoframe have not yet been realized. Herein, we report a rational synthetic strategy for a structurally robust Ir-based multimetallic double-layered nanoframe (DNF) structure, nanoframe@nanoframe. By leveraging the differing kinetics of dual Ir precursors and dual transition metal (Ni and Cu) precursors, a core-shell-type alloy@alloy structure could be generated in a simple one-step synthesis, which was subsequently transformed into a multimetallic IrNiCu DNF with a rhombic dodecahedral morphology via selective etching...
June 14, 2017: ACS Nano
Ayon Karmakar, Suneel Kumar Srivastava
The present work is focused on protective agent free synthesis of interconnected copper cobaltite (Cu0.3Co2.7O4) nanochains by temperature controlled solvothermal method followed by post thermal treatment of the precursors. Further, Cu0.3Co2.7O4 interconnected nanochains are employed as electrocatalyst for water oxidation in alkaline medium for the first time. Extensive studies of physio-chemical properties showed the formation of interconnected 1D nanochains of Cu0.3Co2.7O4 exhibiting larger specific surface area (139...
June 9, 2017: ACS Applied Materials & Interfaces
Hua-Jun Qiu, Jiaojiao Gao, Yu Wang, Li Liu
Using Co-based metal-organic frameworks (MOFs) as precursor, we synthesized cobalt selenide (CoSe2) nanoparticles imbedded in carbon cages. By simply controlling the annealing conditions, phase transformation of CoSe2 from orthorhombic phase to cubic phase has been realized. Benefitting from the metallic character, the cubic phase CoSe2 shows much enhanced electrocatalytic activities for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). The as-prepared cubic phase CoSe2 electrode possesses onset overpotentials of 43 and 200 mV, Tafel slopes of 51 and 83 mV dec-1 for HER and OER, respectively, which are remarkably superior to that of orthorhombic phase CoSe2 catalyst and comparable to those of commercial noble-metal catalysts...
June 9, 2017: Nanotechnology
Pengzuo Chen, Tianpei Zhou, Mengxing Zhang, Yun Tong, Chengan Zhong, Nan Zhang, Lidong Zhang, Changzheng Wu, Yi Xie
Developing non-noble-metal electrocatalysts with high activity and low cost for both the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) is of paramount importance for improving the generation of H2 fuel by electrocatalytic water-splitting. This study puts forward a new N-anion-decorated Ni3 S2 material synthesized by a simple one-step calcination route, acting as a superior bifunctional electrocatalyst for the OER/HER for the first time. The introduction of N anions significantly modifies the morphology and electronic structure of Ni3 S2 , bringing high surface active sites exposure, enhanced electrical conductivity, optimal HER Gibbs free-energy (ΔGH* ), and water adsorption energy change (ΔGH2O* )...
June 9, 2017: Advanced Materials
Feng Yan, Yue Wang, Kaiyue Li, Chunling Zhu, Peng Gao, Chunyan Li, Xitian Zhang, Yu-Jin Chen
A noble-metal-free and high-efficient bifunctional catalyst for overall water splitting is greatly desirable to generate clean and sustainable energy carrier such as hydrogen, but remains enormous challenges. Herein, we design and grow the porous interconnected iron-nickel nitride nanosheets on the carbon fiber cloth (FeNi-N/CFC) combing a facile electrodeposition method and in situ nitrogenization process. The as-synthesized FeNi-N/CFC with a low mass loading of 0.25 mg cm-2 exhibits excellent catalytic activities for both oxygen evolution reaction (OER) with 20 mA cm-2 at overpotential (η) of 232 mV and hydrogen evolution reaction (HER) with 10 mA cm-2 at η = 106 mV...
June 7, 2017: Chemistry: a European Journal
Rong Liu, Yanyong Wang, Dongdong Liu, Yuqin Zou, Shuangyin Wang
An earth-abundant and highly efficient electrocatalyst is essential for oxygen evolution reaction (OER) due to its poor kinetics. Layered double hydroxide (LDH)-based nanomaterials are considered as promising electrocatalysts for OER. However, the stacking structure of LDHs limits the exposure of the active sites. Therefore, the exfoliation is necessary to expose more active sites. In addition, the defect engineering is proved to be an efficient strategy to enhance the performance of OER electrocatalysts. For the first time, this study prepares ultrathin CoFe LDHs nanosheets with multivacancies as OER electrocatalysts by water-plasma-enabled exfoliation...
June 7, 2017: Advanced Materials
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