HREM study of Fe—pillared smectite

1990 ◽  
Vol 48 (4) ◽  
pp. 282-283
Author(s):  
P.L. Hansen ◽  
C. Bender Koch ◽  
S. Mørup
Keyword(s):  
Metal Oxide ◽  
Molecular Sieves ◽  
Direct Evidence ◽  
Interlayer Space ◽  
Active Surface ◽  
Interlayer Spacing ◽  
Active Surface Area ◽  
Oxide Precursor ◽  
Layered Clay ◽  
Structural Methods

During the process of pillaring smectite, a metal oxide precursor is introduced into the interlayer space of the layered clay mineral. By subsequent heating of the precursor, a metal oxide forms, increasing the interlayer spacing 0.5—1.0 nm, as observed in XRD.Pillaring of clays increases the active surface area, and the materials may find use as molecular sieves and catalysts.Most of the information on the oxide pillars has been derived from indirect spectroscopic and structural methods. In the present study we have used HREM to obtain direct evidence for the pillar formation.

Tenacious Mass Transfer Limitations Drive Catalytic Selectivity during Electrochemical Carbon Dioxide Reduction

2019 ◽  
Author(s):  
Kailun Yang ◽  
Recep Kas ◽  
Wilson A. Smith
Keyword(s):  
Surface Area ◽  
High Surface ◽  
High Surface Area ◽  
Catalyst Layer ◽  
Active Surface ◽  
Active Surface Area ◽  
High Concentration ◽  
Copper Electrodes ◽  
Surface Enhanced ◽  
Local Current

<p>This study evaluated the performance of the commonly used strong buffer electrolytes, i.e. phosphate buffers, during CO<sub>2</sub> electroreduction in neutral pH conditions by using in-situ surface enhanced infrared absorption spectroscopy (SEIRAS). Unfortunately, the buffers break down a lot faster than anticipated which has serious implications on many studies in the literature such as selectivity and kinetic analysis of the electrocatalysts. Increasing electrolyte concentration, surprisingly, did not extend the potential window of the phosphate buffers due to dramatic increase in hydrogen evolution reaction. Even high concentration phosphate buffers (1 M) break down within the potentials (-1 V vs RHE) where hydrocarbons are formed on copper electrodes. We have extended the discussion to high surface area electrodes by evaluating electrodes composed of copper nanowires. We would like highlight that it is not possible to cope with high local current densities on these high surface area electrodes by using high buffer capacity solutions and the CO<sub>2</sub> electrocatalysts are needed to be evaluated by casting thin nanoparticle films onto inert substrates as commonly employed in fuel cell reactions and up to now scarcely employed in CO<sub>2</sub> electroreduction. In addition, we underscore that normalization of the electrocatalytic activity to the electrochemical active surface area is not the ultimate solution due to concentration gradient along the catalyst layer.This will “underestimate” the activity of high surface electrocatalyst and the degree of underestimation will depend on the thickness, porosity and morphology of the catalyst layer. </p> <p> </p>

High-speed visualization of metal oxide precursor in multiphase AC arc during nanoparticle formation

2020 ◽  
Vol 59 (SH) ◽  
pp. SHHC08 ◽  
Author(s):  
Manabu Tanaka ◽  
Yuki Saito ◽  
Hiroki Maruyama ◽  
Takayuki Watanabe
Keyword(s):  
Metal Oxide ◽  
High Speed ◽  
Nanoparticle Formation ◽  
Oxide Precursor ◽  
Ac Arc

scholarly journals High-Performance Lead-Acid Batteries Enabled by Pb and PbO2 Nanostructured Electrodes: Effect of Operating Temperature

2021 ◽  
Vol 11 (14) ◽  
pp. 6357
Author(s):  
Roberto Luigi Oliveri ◽  
Maria Grazia Insinga ◽  
Simone Pisana ◽  
Bernardo Patella ◽  
Giuseppe Aiello ◽  
...  
Keyword(s):  
High Performance ◽  
Active Material ◽  
Active Surface ◽  
Effect Of Temperature ◽  
Active Surface Area ◽  
Polycarbonate Membrane ◽  
Nanostructured Electrodes ◽  
Lead Acid Batteries ◽  
Improved Stability ◽  
Lead Acid

Lead-acid batteries are now widely used for energy storage, as result of an established and reliable technology. In the last decade, several studies have been carried out to improve the performance of this type of batteries, with the main objective to replace the conventional plates with innovative electrodes with improved stability, increased capacity and a larger active surface. Such studies ultimately aim to improve the kinetics of electrochemical conversion reactions at the electrode-solution interface and to guarantee a good electrical continuity during the repeated charge/discharge cycles. To achieve these objectives, our contribution focuses on the employment of nanostructured electrodes. In particular, we have obtained nanostructured electrodes in Pb and PbO2 through electrosynthesis in a template consisting of a nanoporous polycarbonate membrane. These electrodes are characterized by a wider active surface area, which allows for a better use of the active material, and for a consequent increased specific energy compared to traditional batteries. In this research, the performance of lead-acid batteries with nanostructured electrodes was studied at 10 C at temperatures of 25, −20 and 40 °C in order to evaluate the efficiency and the effect of temperature on electrode morphology. The batteries were assembled using both nanostructured electrodes and an AGM-type separator used in commercial batteries.

Hollow structure engineering of FeCo alloy nanoparticles electrospun in nitrogen-doped carbon enables high performance flexible all-solid-state zinc–air batteries

2020 ◽  
Vol 4 (4) ◽  
pp. 1747-1753 ◽  
Author(s):  
Yuanyuan Ma ◽  
Wenjie Zang ◽  
Afriyanti Sumboja ◽  
Lu Mao ◽  
Ximeng Liu ◽  
...  
Keyword(s):  
Active Sites ◽  
High Performance ◽  
Hollow Structure ◽  
Active Surface ◽  
Oxygen Electrode ◽  
Active Surface Area ◽  
Active Components ◽  
Nitrogen Doped Carbon ◽  
Structure Engineering ◽  
Kinetics Of

Hollow structuring of active components is an effective strategy to improve the kinetics of oxygen electrode catalysts, arising from the increased the active surface area, the defects on the exposed surface, and the accessible active sites.

scholarly journals Biofilm on the polymer composites - qualitative and quantitative microbiological analysis

2021 ◽  
Author(s):  
Dobrochna Ginter-Kramarczyk ◽  
Izabela Kruszelnicka ◽  
Michał Michałkiewicz ◽  
Przemysław Muszyński ◽  
Stanisław Zajchowski ◽  
...  
Keyword(s):  
Polymer Composites ◽  
Wood Flour ◽  
Biological Membrane ◽  
Polymeric Materials ◽  
Active Surface ◽  
Modern Technology ◽  
Biofilm Reactor ◽  
Active Surface Area ◽  
Microbiological Analysis ◽  
Wood Polymer

Abstract Background Modern technology, which has been getting more and more recognition in the world for the last several years, is the moving bed biofilm reactor (MBBR) technology. Currently, movable biofilters made of basic polymeric materials, polyethylene and polypropylene. Methods An innovative solution in the field, mainly because of the large active surface area for biological membrane can be wood polymer composites (WPC). In the research polypropylene (PP) and polyvinyl chloride (PVC) was used as the matrix. Two types of commercial wood flour also, selected from conifers, were selected for the study: Lignocel C 120 with particle sizes in the range of 70 μm–150 μm and L9 with dimensions of 0.8–1.1 mm and wood chips, which are used on an industrial scale for the production of chipboards, were used as a filler. A quantitative and qualitative analysis of newly formed biofilms was performed. Results The study showed a direct effect of the filler and its particle size on the susceptibility to the formation of the biofilm of on the composites surface. Conclusions Polypropylene PPH 648 T and 40% wt. of L9 type wood flour was the most susceptible to biofilm formation. Pure polypropylene PPH 648 T was the least susceptible material.

Increasing Active Surface Area to Fabricate Ultra-Hydrophobic Surface by Using “Black Silicon” with Bosch Etching Process

2012 ◽  
Vol 12 (6) ◽  
pp. 4919-4927 ◽  
Author(s):  
Nithi Atthi ◽  
Jakrapong Supadech ◽  
Gaetan Dupuy ◽  
On-uma Nimittrakoolchai ◽  
Apirak Pankiew ◽  
...  
Keyword(s):  
Surface Area ◽  
Hydrophobic Surface ◽  
Active Surface ◽  
Etching Process ◽  
Black Silicon ◽  
Active Surface Area

scholarly journals Preparation and Electrocatalytic Characteristics Research of Pd/C Catalyst for Direct Ethanol Fuel Cell

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Qiao Xia Li ◽  
Ming Shuang Liu ◽  
Qun Jie Xu ◽  
Hong Min Mao
Keyword(s):  
Fuel Cell ◽  
Average Particle Size ◽  
Active Surface ◽  
Carbon Support ◽  
Catalytic Performance ◽  
Active Surface Area ◽  
Average Particle ◽  
Ethanol Fuel ◽  
Direct Ethanol Fuel Cell ◽  
Electrochemical Active Surface Area

Two kinds of carbon-support 20% Pd/C catalysts for use in direct ethanol fuel cell (DEFC) have been prepared by an impregnation reduction method using NaBH4and NaH2PO2as reductants, respectively, in this study. The catalysts were characterized by XRD and TEM. The results show that the catalysts had been completely reduced, and the catalysts are spherical and homogeneously dispersed on carbon. The electrocatalytic activity of the catalysts was investigated by electrochemical measurements. The results indicate that the catalysts had an average particle size of 3.3 nm and showed the better catalytic performance, when NaBH4was used as the reducing agent. The electrochemical active surface area of Pd/C (NaBH4) was 56.4 m2·g−1. The electrochemical activity of the Pd/C (NaBH4) was much higher than that of Pd/C (NaH2PO2).

Effect of the Nucleation Layer on TiO2 Nanoflowers Growth via Solvothermal Synthesis

2012 ◽  
Vol 1479 ◽  
pp. 95-100
Author(s):  
Oscar A. Jaramillo ◽  
Reshmi Raman ◽  
Marina E. Rincón
Keyword(s):  
Solvothermal Synthesis ◽  
Room Temperature ◽  
Active Surface ◽  
Dip Coating ◽  
Fixed Number ◽  
Active Surface Area ◽  
Nucleation Layer ◽  
Sensing Properties ◽  
Nucleation Sites ◽  
Ethanol Sensing

ABSTRACTTiO2 nanoflowers were obtained on modified ITO substrates by solvothermal synthesis. Surface modification was achieved with a layer of TiO2 seeds/nucleus obtained by dip-coating at various pH and dip cycles. Field emission scanning electron microscopy results indicated that at all nucleation conditions there was a dual population of TiO2 nanoparticles and nanoflowers. For a particular pH, the effect of increasing the number of dips was to increase the size and number of the nanoflowers, whereas for a fixed number of dips, the increase in pH causes a decrease in nanoflower population. The comparison with solvothermal films obtained on unmodified substrates indicates that TiO2 nanoflowers grew up on the nucleation sites. These microstructural changes determine the active surface area and sensing properties of the solvothermal films. At room temperature, no evidence of superior ethanol sensing properties was found for TiO2 nanoflowers, which show larger resistivity than TiO2 nanoparticles.

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