Intermediate Sr2Co1.5Fe0.5O6−δ Tetragonal Structure between Perovskite and Brownmillerite as a Model Catalyst with Layered Oxygen Deficiency for Enhanced Electrochemical Water Oxidation

ACS Catalysis ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 4327-4337
Author(s):  
Sivasankara Rao Ede ◽  
Candyce N. Collins ◽  
Carlos D. Posada ◽  
Gibin George ◽  
Hui Wu ◽  
...  
Author(s):  
H.W. Zandbergen ◽  
M.R. McCartney

Very few electron microscopy papers have been published on the atomic structure of the copper oxide based superconductor surfaces. Zandbergen et al. have reported that the surface of YBa2Cu3O7-δ was such that the terminating layer sequence is bulk-Y-CuO2-BaO-CuO-BaO, whereas the interruption at the grain boundaries is bulk-Y-CuO2-BaO-CuO. Bursill et al. reported that HREM images of the termination at the surface are in good agreement with calculated images with the same layer sequence as observed by Zandbergen et al. but with some oxygen deficiency in the two surface layers. In both studies only one or a few surfaces were studied.


Author(s):  
Maryvonne Hervieu

Four years after the discovery of superconductivity at high temperature in the Ba-La-Cu-O system, more than thirty new compounds have been synthesized, which can be classified in six series of copper oxides: La2CuO4 - type oxides, bismuth cuprates, YBa2Cu3O7 family, thallium cuprates, lead cuprates and Nd2CuO4 - type oxides. Despite their quite different specific natures, close relationships allow their structures to be simply described through a single mechanism. The fifth first families can indeed be described as intergrowths of multiple oxygen deficient perovskite slabs with multiple rock salt-type slabs, according to the representation [ACuO3-x]m [AO]n.The n and m values are integer in the parent structures, n varying from 0 to 3 and m from 1 to 4; every member of this large family can thus be symbolized by [m,n]. The oxygen deficient character of the perovskite slabs involves the existence or the co-existence of several types of copper environment: octahedral, pyramidal and square planar.Both mechanisms, oxygen deficiency and intergrowth, are well known to give rise easily to nonstoichiometry phenomena. Numerous and various phenomena have actually been characterized in these cuprates, strongly depending on the thermal history of the samples.


2020 ◽  
Vol 49 (3) ◽  
pp. 588-592 ◽  
Author(s):  
Fusheng Li ◽  
Ziqi Zhao ◽  
Hao Yang ◽  
Dinghua Zhou ◽  
Yilong Zhao ◽  
...  

A cobalt oxide catalyst prepared by a flame-assisted deposition method on the surface of FTO and hematite for electrochemical and photoelectrochemical water oxidation, respectively.


MRS Advances ◽  
2020 ◽  
Vol 5 (61) ◽  
pp. 3123-3131
Author(s):  
Mario Flores Nicolas ◽  
Marina Vlasova ◽  
Pedro Antonio Márquez Aguilar ◽  
Mykola Kakazey ◽  
Marcos Mauricio Chávez Cano ◽  
...  

AbstractThe low-temperature synthesis of bricks prepared from high-siliceous clays by the method of plastic molding of blanks was used. For the preparation of brick blanks, binary and ternary mixtures of high-siliceous clays, black sand, and bottle glass cullet were used. Gray-black low-porosity and high-porosity ceramics was obtained by sintering under conditions of oxygen deficiency. It has been established that to initiate plastic in mixtures containing high-siliceous clay, it is necessary to add montmorillonite/bentonite additives, carry out low-temperature sintering, and introduce low-melting glass additives with a melting point ranging from 750 to 800 °C. The performed investigations have shown that the sintering of mixtures with a total content of iron oxide of about 5 wt% under reducing conditions at Tsint. = 800°C for 8 h leads to the formation of glass ceramics consisting of quartz, feldspars, and a phase. The main sources of the appearance of a dark color is the formation of [Fe3+O4]4- and [Fe3+O6]9- anions in the composition of the glass phase and feldspars. By changing the contents of clay, sand, and glass in sintering, it is possible to obtain two types of ceramic materials: (a) in the form of building bricks and (b) in the form of porous fillers.


Author(s):  
Ю.И. Кирова ◽  
Э.Л. Германова

Митохондриогенез и ангиогенез являются ключевыми нейропротекторными механизмами, повышающими устойчивость нервной ткани к условиям гипоксии/ишемии. В настоящее время фармакологическая индукция биогенеза митохондрий является одним из наиболее перспективных и активно разрабатываемых подходов к коррекции ишемических и постишемических нарушений, нейродегенеративных заболеваний и кардиопатий. Выявление факта стимуляции митохондриогенеза эталонными нейропротекторными препаратами позволит существенно расширить представление об их терапевтическом потенциале и принципах применения. Цель исследования - изучение влияния нейропротекторного сукцинатсодержащего препарата мексидол на экспрессию каталитических субъединиц дыхательных ферментов митохондрий, АТФ-синтазы и фактора роста эндотелия сосудов в коре головного мозга крыс с врожденными различиями в устойчивости к дефициту кислорода. Методика. Исследование выполнено на белых беспородных крысах-самцах. Инъекции мексидола (40 мг/кг, внутрибрюшинно) выполняли ежедневно на протяжении 20 сут. Уровень экспрессии каталитических субъединиц дыхательных ферментов митохондрий и АТФ-синтазы, фактора роста эндотелия сосудов и сукцинатного рецептора в ткани коры головного мозга оценивали методом иммуноблоттинга. Общую резистентность организма к острой гипоксии тестировали в гипобарической камере проточного типа при разрежении атмосферы, соответствующем 190 мм рт. ст. (3% О). Результаты. В ходе курса применения мексидола происходило увеличение уровня каталитических субъединиц дыхательных ферментов митохондрий (NDUFV2, SDHA, cyt b, COX1), АТФ-синтазы (ATP5A), фактора роста эндотелия сосудов (VEGF) и сукцинатного рецептора (SUCNR1), особенно выраженное у неустойчивых к гипоксии особей. Заключение. Впервые показана вовлеченность сукцинатсодержащего препарата мексидол в механизмы индукции ферментов энергопродуцирующей системы митохондрий коры головного мозга, что существенно расширяет сложившиеся представления о механизмах его энерготропного действия. Mitochondriogenesis and angiogenesis are crucial neuroprotective mechanisms that increase the resistance of nervous tissue to hypoxia/ischemia conditions. Currently, pharmacological induction of mitochondrial biogenesis is one of the most promising and actively developed approaches for the correction of ischemic and post-ischemic disorders, neurodegenerative diseases and cardiopathies. Revealing the fact of stimulation of mitochondriogenesis with standard neuroprotective drugs will significantly expand the understanding of their therapeutic potential and principles of application. The aim of the research was to study the effect of the neuroprotective succinate-containing drug mexidol on the expression of catalytic subunits of the respiratory enzymes of mitochondria, ATP-synthase and vascular endothelial growth factor in the cerebral cortex of rats with inborn differences in resistance to oxygen deficiency. Methods. The study was carried out on white mongrel rats-males injections of mexidol (40 mg/kg, intraperitoneally) were performed daily for 20 days. The expression level of the catalytic subunits of the respiratory enzymes of mitochondria and ATP-synthase, vascular endothelial growth factor and succinate receptor in the tissue of the cerebral cortex was assessed by immunoblotting. The total resistance of the organism to acute hypoxia was tested in a hypobaric chamber with an atmosphere underpressure corresponding to 190 mm Hg (3% O). Results. During the injection course of mexidol, there was an increase in the level of catalytic subunits of the respiratory enzymes of mitochondria (NDUFV2, SDHA, cyt b, COX1), ATP-synthase (ATP5A), vascular endothelial growth factor (VEGF) and succinate receptor (SUCNR1), especially pronounced in rats with low-resistance to hypoxia. Conclusion. The study revealed for the first time the involvement of the succinate-containing drug mexidol in the mechanisms of induction of enzymes of the energy-producing system of the mitochondria of the cerebral cortex, which significantly expands the existing ideas about the mechanisms of its energy-tropic action.


2020 ◽  
Author(s):  
Camilo A. Mesa ◽  
Ludmilla Steier ◽  
Benjamin Moss ◽  
Laia Francàs ◽  
James E. Thorne ◽  
...  

<p><i>Operando</i> spectroelectrochemical analysis is used to determine the water oxidation reaction kinetics for hematite photoanodes prepared using four different synthetic procedures. Whilst these photoanodes exhibit very different current / voltage performance, their underlying water oxidation kinetics are found to be almost invariant. Lower photoanode performance was found to correlate with the observation of optical signals indicative of charge accumulation in mid-gap oxygen vacancy states, indicating these states do not contribute directly to water oxidation.</p>


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