Mesoporous tantalum oxide photocatalysts for Schrauzer-type conversion of dinitrogen to ammonia

2005 ◽  
Vol 83 (4) ◽  
pp. 308-314 ◽  
Author(s):  
Chaoyang Yue ◽  
Michel L Trudeau ◽  
David Antonelli
Keyword(s):  
Surface Area ◽  
Tantalum Oxide ◽  
Catalytic Efficiency ◽  
Mesoporous Structure ◽  
Turnover Rates ◽  
Type Conversion ◽  
Electron Hole ◽  
Surface Areas ◽  
Before And After ◽  
First Time

Mesoporous tantalum oxide, Fe3+-doped mesoporous tantalum oxide, and bis(toluene) titanium reduced mesoporous tantalum oxide were used for the first time as Schrauzer-type photocatalysts for the conversion of dinitrogen to ammonia. The materials were characterized by XRD, TEM, XPS, and nitrogen absorption before and after catalytic runs. The results showed low to moderate activities depending on the composition. In contrast to previously studied Ti catalysts, Fe doping and heat pretreatment were not prerequisites for photocatalytic activity, but did improve the turnover rates by up to a factor of two. The optimal Fe loading for the tantalum oxides was found to be 1 wt% and the optimal heating condition at 300 °C for 3 h. Increased surface area and heat treatment were also found to improve activities. Contrary to our expectations, reduction of the mesostructure with bis(toluene) titanium had little effect on the catalytic activity. In spite of the dramatically higher surface areas of the mesoporous tantalum oxides as compared with bulk titanias used previously in this process, the overall catalytic activities were still less than those obtained in the Schrauzer system. This suggests that the increase in diffusion and surface area offered by the mesoporous structure is offset by the smaller crystalline domain sizes in the walls of the structure, leading to poor electron-hole separation and a reduction in catalytic efficiency. Key words: mesoporous, Schrauzer, ammonia, photocatalysis, tantalum oxide.

Synthesis and Characterization of RuO2 Anode Materials with Large Surface Areas for Oxygen Evolution Reaction

2012 ◽  
Vol 15 (4) ◽  
pp. 271-276 ◽  
Author(s):  
Yang Zhang ◽  
Lixia Yue ◽  
Ke Teng ◽  
Shiyong Yuan ◽  
Hongchao Ma
Keyword(s):  
Porous Structure ◽  
Electrochemical Properties ◽  
Surface Area ◽  
Oxygen Evolution ◽  
Oxygen Evolution Reaction ◽  
Mesoporous Structure ◽  
Large Surface Area ◽  
Precipitation Method ◽  
Surface Areas ◽  
Lower Temperature

A novel olivary or petal-like RuO2 material with large surface area was successfully synthesized by surfactant-assisted homogeneous precipitation method using urea and dodecyl sulfate as the source reagent. The surface morphology, structural, and electrochemical properties of as-synthesized RuO2 materials were characterized by x-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), Cyclic voltammetry (CV), N2 adsorption–desorption isotherms and polarization curve for oxygen evolution reaction (OER). It was found that the morphology and crystalline structures and electrochemical properties of as-synthesized RuO2 materials were strongly dependent on the calcining temperature. The ruthenium-surfactant mesophase with mesoporous structure transformed from network to regular olivary or petal-like RuO2 materials and remaining partial mesoporous character after calcination at lower temperature (i.e., 300 and 400 °C). However, the mesophase transformed into RuO2 agglomeration consisted of nanosized particles after calcination at 650 °C, which may be attributed to complete deorganization and porous structure collapse of RuO2 materials. In addition, the as-synthesized RuO2 materials showed higher specific surface area and better electrochemical activities for oxygen evolution reaction compared with the RuO2 prepared without surfactant. The electrochemical activity of as-synthesized RuO2 material calcined at 400 °C is about 3 times than that of RuO2 prepared without surfactant for oxygen evolution reaction. This can be attributed to the porous structure and large surface area of as-synthesized RuO2 materials.

scholarly journals Accelerated room-temperature crystallization of ultrahigh-surface-area porous anatase titania by storing photogenerated electrons

2017 ◽  
Vol 53 (10) ◽  
pp. 1619-1621 ◽  
Author(s):  
Juan Su ◽  
Xiaoxin Zou ◽  
Binghan Li ◽  
Hui Chen ◽  
Xinhao Li ◽  
...  
Keyword(s):  
Reaction Time ◽  
Surface Area ◽  
Room Temperature ◽  
Surface Areas ◽  
Photogenerated Electrons ◽  
Anatase Titania ◽  
First Time ◽  
Temperature Crystallization

A technology for storing photogenerated electrons is for the first time applied for significantly accelerating the crystallization of amorphous TiO2 at room temperature (reducing the reaction time from 80 to 2 days). The resulting porous anatase titania exhibits ultrahigh surface areas up to 736 m2 g−1.

scholarly journals Preparation of Magnetically Driven Nickel Phosphide Nanowires and Their Electrochemical Properties

2021 ◽  
Vol 12 (1) ◽  
pp. 49
Author(s):  
Hye-Won Kim ◽  
Heon-Cheol Shin
Keyword(s):  
Aspect Ratio ◽  
Surface Area ◽  
Phosphorus Content ◽  
Nickel Phosphide ◽  
Phase Synthesis ◽  
Reaction Surface ◽  
Surface Areas ◽  
Low Phosphorus ◽  
Degradation Degree ◽  
First Time

In this study, nickel phosphide nanowires with various structures and compositions were fabricated for the first time via magnetically-assisted liquid phase synthesis. The curvature and aspect ratio of the nanowires largely depended on the strength of the magnetic field applied during synthesis. Their phosphorus content together with the morphology were significantly modified according to the pH and reducing agent concentration. Nanowires with different structures and phosphorus contents were preliminarily tested for their capabilities to serve in general electrochemical applications. The degree of reaction (i.e., amount of reaction charge) increased with increases in the reaction area and phosphorus content of the nanowires. The rate characteristics of the reaction showed a peculiar increasing trend for a small reaction surface area and low phosphorus content. A change in the ohmic overpotential according to the nanowire curvature (aspect ratio) and porosity was suggested to be the reason for this unusual trend. Electrodes with high phosphorus contents or high reaction surface areas rapidly deteriorated during repetitive redox reactions. Based on the results for the degradation degree, the effect of the reaction surface area dominated that of the phosphorus content in the deterioration of the nickel phosphide nanowires.

SEM and BET Methods for Investigating the Structure and Morphology of Co - Ce Catalysts for Production of Light Olefins

2008 ◽  
Vol 61 (2) ◽  
pp. 144 ◽  
Author(s):  
Ali A. Mirzaei ◽  
Maryam Galavy ◽  
Vahid Eslamimanesh
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Catalytic Performance ◽  
Light Olefins ◽  
Molar Ratio ◽  
Surface Areas ◽  
Preparation Conditions ◽  
Bet Specific Surface Area ◽  
Before And After

Co–Ce catalysts prepared by the coprecipitation method were tested for production of light olefins. The effect of different preparation conditions including the [Co]/[Ce] molar ratio, aging time, calcination conditions, different supports, and loading of optimum support on the structure and catalytic performance of different catalysts were investigated. It was found that catalyst containing 80% Co/20% Ce/15% SiO2, which was aged for 2 h and calcined at 600°C for 6 h, is the optimum modified catalyst for the conversion of synthesis gas to light olefins. Characterization of both precursors and calcined catalysts (before and after the test) was carried out using scanning electron microscopy (SEM) and Brunauer-Emmett-Teller (BET) specific surface area measurements. The morphology of the catalysts was investigated by SEM and the surface areas of these catalysts were studied by BET. It was shown that all of the different preparation variables influenced the morphology and also the specific surface area of the catalyst precursors and calcined catalysts.

Formation and processing of mesoporous barium titanate powders via the micelle template method

2006 ◽  
Vol 21 (4) ◽  
pp. 941-946
Author(s):  
Hong-Wen Wang ◽  
Chien-Hung Kuo ◽  
Tsai-Huei Liao ◽  
Ren-Jay Lin ◽  
Syh-Yuh Cheng
Keyword(s):  
Electron Microscopy ◽  
Barium Titanate ◽  
Surface Area ◽  
Self Assembly ◽  
Structural Characteristics ◽  
Mesoporous Structure ◽  
Surface Areas ◽  
Transmission Electron ◽  
Organic Surfactant ◽  
Titanium Tetra Isopropoxide

Mesoporous barium titanate powders having a 100- to 300-nm size were prepared by hydration and condensation of titanium tetra-isopropoxide and barium precursors in the presence of an organic surfactant, tetradecylamine, which was used as a self-assembly micelle. The processing and sintering of these mesoporous barium titanate powders has been investigated. X-ray diffraction, scanning electron microscopy, and transmission electron microscopy were used to identify the structural characteristics and morphologies of the powders. Mesoporous wormhole-like powders with surface areas around 53 ∼ 108 m2/g could be obtained after removing the micelle organics by calcination at 400 °C for 3 h. Powders derived using barium hydroxide were found to form a larger pore size and a higher surface area. The addition of acetic acid was also effective in increasing the surface area. A formation mechanism for the mesoporous structure is depicted. Heat treatment caused the mesoporous spheres to shrink, and 155- ∼ 330-nm grain sizes were readily obtained after pressureless sintering at 900 ∼ 1000 °C for 1 h in air.

Cell morphology, volume, and surface area determinations from multilevel contouring within HVEM micrographs of serial sections and whole-cell mounts

1987 ◽  
Vol 45 ◽  
pp. 588-589
Author(s):  
M. Marko ◽  
A. Leith ◽  
D. Parsons
Keyword(s):  
Surface Area ◽  
Electron Micrographs ◽  
Cell Morphology ◽  
Individual Variation ◽  
Serial Section ◽  
Stereo Pair ◽  
Complex Structures ◽  
Serial Sections ◽  
Surface Areas ◽  
Computer Based

The use of serial sections and computer-based 3-D reconstruction techniques affords an opportunity not only to visualize the shape and distribution of the structures being studied, but also to determine their volumes and surface areas. Up until now, this has been done using serial ultrathin sections.The serial-section approach differs from the stereo logical methods of Weibel in that it is based on the Information from a set of single, complete cells (or organelles) rather than on a random 2-dimensional sampling of a population of cells. Because of this, it can more easily provide absolute values of volume and surface area, especially for highly-complex structures. It also allows study of individual variation among the cells, and study of structures which occur only infrequently.We have developed a system for 3-D reconstruction of objects from stereo-pair electron micrographs of thick specimens.

Untersuchungen zur Quantifizierung der Änderung der Skelettmuskeldurchblutung nach Gefäßrevaskularisationen mit einem 99mTechnetiummarkierten Tracer

1990 ◽  
Vol 29 (05) ◽  
pp. 215-220 ◽  
Author(s):  
R. Benning ◽  
K. Nagel ◽  
M. Jugenheimer ◽  
S. Fischer ◽  
S. Worthmann ◽  
...  
Keyword(s):  
Transluminal Angioplasty ◽  
Lower Limbs ◽  
Surgical Patients ◽  
Treadmill Test ◽  
Negative Results ◽  
Clinical Observations ◽  
Before And After ◽  
Comparative Results ◽  
First Time ◽  
Percutaneous Transluminal

A new 99mTc-labelled tracer (99mTc-Sestanriibi) was used for the first time to demonstrate the perfusion of the skeletal muscle. In 16 patients with obstructive atherosclerosis of the lower limbs the change of perfusion of thigh and lower leg was studied with SPECT before and after vascular surgery (n = 11) or percutaneous transluminal angioplasty (n = 5). Comparative results of scintigraphic measurements and clinical observations (ancle-arm pressure, treadmill test) in 10 surgical patients (14 operated legs) showed correct positive or negative results in 86% (12/14).

Ti3C2-MXene/Bismuth Ferrite Nanohybrids for Efficient Degradation of Organic Dye and Colorless Pollutant

2019 ◽  
Author(s):  
Ayesha Tariq ◽  
M. Abdullah Iqbal ◽  
S. Irfan Ali ◽  
Muhammad Z. Iqbal ◽  
Deji Akinwande ◽  
...  
Keyword(s):  
Surface Area ◽  
Low Cost ◽  
Bismuth Ferrite ◽  
Organic Dye ◽  
Two Dimensional ◽  
Electron Hole ◽  
Photocatalytic Application ◽  
Electron Hole Pair ◽  
Pair Generation ◽  
Photocatalytic Applications

<p>Nanohybrids, made up of Bismuth ferrites/Carbon allotropes, are extensively used in photocatalytic applications nowadays. Our work proposes a nanohybrid system composed of Bismuth ferrite nanoparticles with two-dimensional (2D) MXene sheets namely, the BiFeO<sub>3</sub> (BFO)/Ti<sub>3</sub>C<sub>2</sub> (MXene) nanohybrid for enhanced photocatalytic activity. We have fabricated the BFO/MXene nanohybrid using simple and low cost double solvent solvothermal method. The SEM and TEM images show that the BFO nanoparticles were attached onto the MXene surface and in the inter-layers of two-dimensional (2D) MXene sheets. The photocatalytic application is tested for the visible light irradiation which showed the highest efficiency among all pure-BFO based photocatalysts, i.e. 100% degradation in 42 min for organic dye (Congo Red) and colorless aqueous pollutant (acetophenone) in 150 min, respectively. The present BFO-based hybrid system exhibited the large surface area of 147 m<sup>2</sup>g<sup>-1</sup>measured via Brunauer-Emmett-Teller (BET) sorption-desorption technique, and is found to be largest among BFO and its derivatives. Also, the photoluminescence (PL) spectra indicate large electron-hole pair generation. Fast and efficient degradation of organic molecules is supported by both factors; larger surface area and lower electron-hole recombination rate. The BFO/MXene nanohybrid presented here is a highly efficient photocatalyst compared to other nanostructures based on pure BiFeO<sub>3</sub> which makes it a promising candidate for many future applications.</p>

Trombodynamics Method in the Assessment of Coagulation Parameters in Psychopharmacotherapy of Endogenous Mental Disorders

Psychiatry ◽  
2020 ◽  
Vol 18 (4) ◽  
pp. 16-25
Author(s):  
N. S. Karpova ◽  
O. S. Brusov ◽  
I. V. Oleichik ◽  
M. I. Faktor ◽  
N. S. Levchenko ◽  
...  
Keyword(s):  
Mental Disorders ◽  
Response To Therapy ◽  
Procoagulant Activity ◽  
Coagulation Activity ◽  
Continuous Type ◽  
Chronic Neuroinflammation ◽  
Psychopharmacological Treatment ◽  
Before And After ◽  
First Time ◽  
Schizotypal Disorder

Background: currently, it has been proven that the pathogenesis of endogenous mental disorders is associated with the process of neuroinflammation in the brain of patients. It is also known that chronic neuroinflammation, accompanied by a violation the permeability of the blood-brain barrier. It is accompanied by the activation of platelets that generate procoagulant microparticles, which leads to a disturbance of the hemostasis system, causing an increase in blood clotting in patients. Objective: to investigate the dynamics of procoagulant activity of blood in patients with endogenous mental disorders before and after psychopharmacotherapy.Patients and methods: the study included 185 patients aged 16 to 64 years with the following mental disorders: schizophrenia with attack-like/attack-progressive/continuous type of course (F20.00–2), affective disease (F31.1–5; F32.0–3; F33.0–3), schizotypal disorder with affective fluctuations (F21.3–4). The thrombodynamic test (TD) was performed on T-2 Trombodynamis device according to the manufacturer’s instructions (Hemacore LLC, Moscow, Russia). All patients received standard pharmacotherapy according to their condition.Results: a significant decrease of procoagulant activity of spontaneous clots in the patients’ blood after psychopharmacological treatment is observed. Our data on the positive dynamics of changes in the values of TD test’s indicators in most of the examined patients suggest that a decrease in the coagulation activity of the patients’ blood as a result of treatment may be associated with the anti- inflammatory effect of antipsychotics and antidepressants.Conclusion: for the first time, it was shown that there is a positive dynamic in changing the values of the main parameters of the TD test in most patients with endogenous mental diseases. The results of TD tests can be the basis for monitoring the response to therapy.

scholarly journals Rugae-like FeP nanocrystal assembly on a carbon cloth: an exceptionally efficient and stable cathode for hydrogen evolution

Nanoscale ◽  
2015 ◽  
Vol 7 (25) ◽  
pp. 10974-10981 ◽  
Author(s):  
Xiulin Yang ◽  
Ang-Yu Lu ◽  
Yihan Zhu ◽  
Shixiong Min ◽  
Mohamed Nejib Hedhili ◽  
...  
Keyword(s):  
Gas Phase ◽  
Surface Area ◽  
Hydrogen Evolution ◽  
Hydrogen Generation ◽  
High Surface ◽  
High Surface Area ◽  
Catalytic Efficiency ◽  
Carbon Cloth ◽  
Nanocrystal Assembly

High surface area FeP nanosheets on a carbon cloth were prepared by gas phase phosphidation of electroplated FeOOH, which exhibit exceptionally high catalytic efficiency and stability for hydrogen generation.

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