scholarly journals Aplicación de nanopartículas de IrO2-WO3 como material anódico para la Reacción de Evolución de Oxígeno en un medio ácido

2019 ◽  
pp. 9-15
Author(s):  
Jesús Ramsés Cardona-Canto ◽  
Julio César Cruz-Argüello ◽  
Danna Lizeth Trejo-Arroyo ◽  
Daniel Canté-Góngora
Keyword(s):  
Room Temperature ◽  
Isopropyl Alcohol ◽  
Chemical Reduction ◽  
Electrochemical Techniques ◽  
H2 Production ◽  
Mechanical Mixing ◽  
Calcination Process ◽  
Maximum Current Density ◽  
Lower Activation ◽  
Maximum Current

The hydrogen is an attractive energy carrier and electrolysis of water is the most efficient to H2 production process. The OER in the anode is the limiting reaction being the case of study. In the present work materials based on IrO2 and WO3 were developed in different mechanical mixing 100, 70:30, 50:50, 30:70, respectively, by means of a mechanical mixture from two chemical reduction syntheses. The IrO2 was obtained by 6.25 mM of IrCl3 dissolved in isopropyl alcohol by adjusting the pH with 1M NaOH and a 0.5 mol NH4OH reductant was applied by adjusting a basic pH of 13. The obtained precursor was filtered and calcined at 400 ° C for 1hr. WO3 was obtained from 10mM WCl6 dissolved in isopropyl alcohol and polyethylene glycol, generating a precursor of W (OH)x followed by a calcination process at 500 ° C for 1hr. The material was characterized by electrochemical techniques of CV, LV and EIS. The IrO2-WO3 (50:50) material has lower activation energy of overpotential at room temperature, and a maximum current density close to 20 mA /cm2 at 1.8V vs Hg/Hg2SO4.

Room Temperature Alkali Metal Reduction of Carbon Dioxide

2020 ◽  
Author(s):  
Lucas A. Freeman ◽  
Akachukwu D. Obi ◽  
Haleigh R. Machost ◽  
Andrew Molino ◽  
Asa W. Nichols ◽  
...  
Keyword(s):  
Alkali Metal ◽  
Alkali Metals ◽  
Room Temperature ◽  
Chemical Reduction ◽  
Bond Cleavage ◽  
Open Shell ◽  
Metal Reduction ◽  
One Pot ◽  
Earth Abundant ◽  
Electron Reduction

The reduction of the relatively inert carbon–oxygen bonds of CO<sub>2</sub> to access useful CO<sub>2</sub>-derived organic products is one of the most important fundamental challenges in synthetic chemistry. Facilitating this bond-cleavage using earth-abundant, non-toxic main group elements (MGEs) is especially arduous because of the difficulty in achieving strong inner-sphere interactions between CO<sub>2</sub> and the MGE. Herein we report the first successful chemical reduction of CO<sub>2</sub> at room temperature by alkali metals, promoted by a cyclic(alkyl)(amino) carbene (CAAC). One-electron reduction of CAAC-CO<sub>2</sub> adduct (<b>1</b>) with lithium, sodium or potassium metal yields stable monoanionic radicals clusters [M(CAAC–CO<sub>2</sub>)]<sub>n</sub>(M = Li, Na, K, <b> 2</b>-<b>4</b>) and two-electron alkali metal reduction affords open-shell, dianionic clusters of the general formula [M<sub>2</sub>(CAAC–CO<sub>2</sub>)]<sub>n </sub>(<b>5</b>-<b>8</b>). It is notable that these crystalline clusters of reduced CO<sub>2</sub> may also be isolated via the “one-pot” reaction of free CO<sub>2</sub> with free CAAC followed by the addition of alkali metals – a reductive process which does not occur in the absence of carbene. Each of the products <b>2</b>-<b>8</b> were investigated using a combination of experimental and theoretical methods.<br>

Synthesis of CaWO4:(Eu3+,Tb3+) Thin Films by a Two-Step Method at Room Temperature

2013 ◽  
Vol 710 ◽  
pp. 170-173
Author(s):  
Lian Ping Chen ◽  
Yuan Hong Gao
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Phase Composition ◽  
Room Temperature ◽  
Electrochemical Techniques ◽  
Luminescent Properties ◽  
X Ray Diffraction ◽  
Step Method ◽  
X Ray ◽  
Rare Earth Doped

It is hardly possible to obtain rare earth doped CaWO4thin films directly through electrochemical techniques. A two-step method has been proposed to synthesize CaWO4:(Eu3+,Tb3+) thin films at room temperature. X-ray diffraction, energy dispersive X-ray analysis, spectrophotometer were used to characterize their phase, composition and luminescent properties. Results reveal that (Eu3+,Tb3+)-doped CaWO4films have a tetragonal phase. When the ratio of n (Eu)/n (Tb) in the solution is up to 3:1, CaWO4:(Eu3+,Tb3+) thin film will be enriched with Tb element; on the contrary, when the ratio in the solution is lower than 1:4, CaWO4:(Eu3+,Tb3+) thin film will be enriched with Eu element. Under the excitation of 242 nm, sharp emission peaks at 612, 543, 489 and 589 nm have been observed for CaWO4:(Eu3+,Tb3+) thin films.

Study of Lithium Polymer Interface to Enhance Efficiency and Safety in Lithium/Water Batteries

2000 ◽  
Author(s):  
Jeong-Ju Cho ◽  
M. Urquidi-Macdonald
Keyword(s):  
Lithium Hydroxide ◽  
Organic Electrolytes ◽  
Hydroxide Ion ◽  
Maximum Current Density ◽  
Polymer Interface ◽  
Gel Electrolytes ◽  
Effect Of Additives ◽  
Maximum Current ◽  
Flux Measurements ◽  
Enhance Efficiency

Abstract New gel electrolytes composed of silica powder and organic electrolytes for the application of lithium/seawater batteries were tested with a porous separator. The maximum current density was ∼25mA/cm2. The discharging current was decreased suddenly because of two reasons. One reason is that the porous separator became clogged with lithium hydroxide and the other is because of the deposition of lithiumsilicate on the lithium surface, which was confirmed using SEM, XPS and hydroxide ion flux measurements. The efficiency (5 ∼ 27%) of the lithium oxidation was also obtained by measuring the hydrogen volume. The efficiency is strongly dependent on the ambient temperature. The effect of additives and other gel systems was also investigated.

scholarly journals Synthesis of cobalt nanowires in aqueous solution under an external magnetic field

2016 ◽  
Vol 7 ◽  
pp. 990-994 ◽  
Author(s):  
Xiaoyu Li ◽  
Lijuan Sun ◽  
Hu Wang ◽  
Kenan Xie ◽  
Qin Long ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Aqueous Solution ◽  
External Magnetic Field ◽  
Room Temperature ◽  
Magnetic Measurements ◽  
Chemical Reduction ◽  
Average Diameter ◽  
Firm Structure ◽  
Cobalt Nanowires ◽  
First Time

In contrast to the majority of related experiments, which are carried out in organic solvents at high temperatures and pressures, cobalt nanowires were synthesized by chemical reduction in aqueous solution with the assistance of polyvinylpyrrolidone (PVP) as surfactant under moderate conditions for the first time, while an external magnetic field of 40 mT was applied. Uniform linear cobalt nanowires with relatively smooth surfaces and firm structure were obtained and possessed an average diameter of about 100 nm with a coating layer of PVP. By comparison, the external magnetic field and PVP were proven to have a crucial influence on the morphology and the size of the synthesized cobalt nanowires. The prepared cobalt nanowires are crystalline and mainly consist of cobalt as well as a small amount of platinum. Magnetic measurements showed that the resultant cobalt nanowires were ferromagnetic at room temperature. The saturation magnetization (M s) and the coercivity (H c) were 112.00 emu/g and 352.87 Oe, respectively.

scholarly journals Bright Alloy CdZnSe/ZnSe QDs with Nonquenching Photoluminescence at High Temperature and Their Application to Light-Emitting Diodes

2019 ◽  
Vol 2019 ◽  
pp. 1-8
Author(s):  
Tingting Zhang ◽  
Xugu Zhang ◽  
Peizhi Yang ◽  
Jinke Bai ◽  
Chun Chang ◽  
...  
Keyword(s):  
Quantum Dots ◽  
High Temperature ◽  
Quantum Yields ◽  
Excellent Performance ◽  
Light Emitting ◽  
Light Emitting Devices ◽  
Maximum Current Density ◽  
Luminescence Efficiency ◽  
Maximum Current ◽  
Pl Quenching

Stable luminance properties are essential for light-emitting devices with excellent performance. Thermal photoluminescence (PL) quenching of quantum dots (QDs) under a high temperature resulting from a surface hole or electron traps will lead to unstable and dim brightness. After treating CdZnSe/ZnSe QDs with TBP, which is a well-known passivation reagent of the anions, the excess Se sites on the surface of the QDs were removed and their PL quantum yields (QYs) was improved remarkable. Furthermore, after TBP treatment, the CdZnSe/ZnSe QDs exhibit no quenching phenomena even at a high temperature of 310°C. The electroluminescent light-mitting diodes based on the QDs with TBP treatment also demonstrated satisfied performance with a maximum current density of 1679.6 mA/cm2, a peak luminance of 89500 cd/m2, and the maximum values of EQE and luminescence efficiency are 15% and 14.9 cd/A, respectively. The performance of the fabricated devices can be further improved providing much more in-depth studies on the CdZnSe/ZnSe QDs.

Biocompatible Hydroxyapatite Derive from Selayang Fish Bone via Mechanochemical Treatment

2020 ◽  
Vol 307 ◽  
pp. 339-344
Author(s):  
Ishak Qayyum Afiqah ◽  
Nik Aziz Nik Ali ◽  
Abd Majid Siti Nurhaziqah ◽  
Hasiah Salleh
Keyword(s):  
Room Temperature ◽  
Fish Bone ◽  
X Ray Diffraction ◽  
Synthetic Process ◽  
Calcination Process ◽  
Natural Sources ◽  
X Ray ◽  
Fish Bones ◽  
Phosphate Mineral

Age of monstrous amount of underutilized marine processing byproducts has been perceived as waste and many effort were given to utilize these materials in various application. With an incredible number of study on these byproducts, some compound were identified and apply for human utilization. Hydroxyapatite (HAp) is the main inorganic calcium phosphate mineral with excellent osteoconductivity, good bioactivity and biocompatibility. The production of HAp powder from synthetic process involves many chemicals with complicated procedures. Due to this matter, the raw HAp powder was extracted from natural sources selayang fish bones. Extortion process started with boiling fish bones to eliminate adherent fish meats. After calcination process fish bone were dried in room temperature before crushed by using grinder to obtain the powder. Next, the powder undergo calcination process at 900°C for 5 hours. The characterization of raw HAp was done via X-ray Diffraction, Fourier Transform Infrared Spectometer, Scanning Electron Microscopy, and Thermogravimetric analysis.

Properties of human atrial ICa at physiological temperatures and relevance to action potential

1997 ◽  
Vol 272 (1) ◽  
pp. H227-H235 ◽  
Author(s):  
G. R. Li ◽  
S. Nattel
Keyword(s):  
Action Potential ◽  
Human Atrium ◽  
Atrial Myocytes ◽  
Human Atrial Myocytes ◽  
Maximum Current Density ◽  
Rate Dependent ◽  
Atrial Cells ◽  
Maximum Current ◽  
Reduced Rate

There are no published characterizations of Ca2+ current (ICa) at physiological temperatures in human atrium. Depolarization of human atrial myocytes at 36 degrees C elicited ICa that peaked at +10 mV, with a mean maximum current density of 10.8 +/- 1.1 pA/pF and no evidence for T-type current. Overlap between activation and inactivation curves and incomplete inactivation during pulses comparable to normal action potential duration (APD) were compatible with the observed role of ICa in maintaining the plateau. ICa was frequency dependent between 0.1 and 2 Hz and ICa blockade with 0.2 mM Cd2+ reduced rate-dependent changes in APD: under control, APD at 90% repolarization was 230 +/- 15 ms at 0.1 Hz and 178 +/- 14 ms at 2 Hz (decrease of 52 +/- 5 ms); with Cd2+, values were 121 +/- 7 ms at 0.1 H2 and 115 +/- 6 ms at 2 Hz (decrease of 6 +/- 3 ms, P < 0.01) Isoproterenol (1 microM) increased ICa and prolonged APD from 138 +/- 13 to 199 +/- 15 ms (P < 0.01). These results indicate that, in human atrial cells at 36 degrees C, the properties of L-type ICa contribute importantly to the rate-dependent and autonomic control of APD.

Superhydrophobic Silicon Surface with Micro/Nanocomposite Structure Formed by 2-Step Wet Etching

2013 ◽  
Vol 747 ◽  
pp. 542-546 ◽  
Author(s):  
Kensuke Nishioka ◽  
Takatoshi Yasui
Keyword(s):  
Potassium Hydroxide ◽  
Silicon Surface ◽  
Room Temperature ◽  
Isopropyl Alcohol ◽  
Alcohol Solution ◽  
Wet Etching ◽  
Nanocomposite Structure ◽  
Maximum Value ◽  
O 11 ◽  
Stain Etching

The micro/nanocomposite structure on silicon surface was formed by a simple 2-step chemical etching with a potassium hydroxide anisotropic etching and a stain etching in order to obtain a superhydrophobic silicon surface. Micro-sized pyramids structure was formed in a mixture of 3 wt.% potassium hydroxide with 8 vol.% isopropyl alcohol solution at 80C for 60 min. The formation of the nanosized structure was performed by stain etching at room temperature using nitric acid (HNO3) / hydrofluoric acid (HF) aqueous solutions. The silicon surface had the superhydrophobic surface. The contact angle was measured and the maximum value was 167o for the condition of second etching with HF : HNO3 : H2O = 11 : 1 : 3.

Sign in / Sign up

Export Citation Format

Share Document