Cooperative Motion in Water–Methanol Clusters Controls the Reaction Rates of Heterogeneous Photocatalytic Reactions

2021 ◽  
Author(s):  
Bei-Bei Xu ◽  
Min Zhou ◽  
Man Ye ◽  
Ling-Yun Yang ◽  
Hai-Feng Wang ◽  
...  
Keyword(s):  
Reaction Rates ◽  
Cooperative Motion ◽  
Photocatalytic Reactions

Microfluidic Photocatalytic Water-Splitting Reactors

2012 ◽  
Author(s):  
Syed Saad Ahsan ◽  
David Erickson
Keyword(s):  
Water Splitting ◽  
Sol Gel ◽  
Reaction Rates ◽  
Transfer Efficiency ◽  
Kinetic Properties ◽  
Wet Impregnation ◽  
Co Catalyst ◽  
Photocatalytic Water Splitting ◽  
Photocatalytic Reactions ◽  
Kinetics Of

In this work, we present a novel microfluidic photocatalytic water-splitting reactor. Optofluidics offers advantages over conventional reactors in terms of improved photon transfer efficiency and mass transfer efficiency and are therefore the ideal platform for photocatalytic reactions. Our device is a planar optofluidic device which we used to study the kinetics of Platinum-Impregnated Titanium Oxide as the oxygen and hydrogen producing photocatalyst redox mediated by Iodide/Iodate species. We deposit our catalysts via a sol-gel method while the platinum co-catalyst is added by wet impregnation via reduction in Sodium Borohydride. The reactions are performed under a 100W Hg lamp and reaction rates are inferred by measuring the depletion of the two Iodine species via UV-vis absorption spectrophotometry. Our results indicate that reaction rates and efficiencies can be enhanced by using an optofluidic platform as opposed to the conventional slurry reactor used in previous experiments for this class of reaction. We believe that the micro-optofluidic platform of our device offers the benefit of measuring the kinetic properties of these class of reactions quickly and cheaply for the goals of further optimization.

Photocatalytic Reactions of Titanium Dioxide for Active Packaging Application

2013 ◽  
Vol 313-314 ◽  
pp. 131-134
Author(s):  
Kanokwan Somkid ◽  
Pailin Ngaotrakanwiwat
Keyword(s):  
Sol Gel ◽  
Reaction Rates ◽  
Molar Ratio ◽  
Ethylene Oxidation ◽  
Photocatalytic Reaction ◽  
Free Oxygen ◽  
Tio2 Particles ◽  
Photocatalytic Reactions ◽  
Adsorption Rates ◽  
Oxygen Concentrations

The adsorption and photocatalytic reactions of ethylene and oxygen were investigated by sol-gel routed TiO2 particles. The dependence of ethylene –free oxygen concentrations, oxygen-free ethylene concentrations and the molar ratio of C2H4:O2 in the gas mixture on adsorption and photocatalytic reaction rates were examined. The increase of ethylene –free oxygen concentrations or oxygen-free ethylene concentrations can enhance the adsorption rates while decreasing photoreaction rates. The presence of ethylene and oxygen can increase adsorption rates leading to enhance photocatalytic rates. The photocatalytic rates of ethylene oxidation and oxygen reduction were 10-8 mol. s-1.g-1 evenly at C2H4:O2 molar ratio equal to 3:1.

scholarly journals Defective Grey TiO2 with Minuscule Anatase–Rutile Heterophase Junctions for Hydroxyl Radicals Formation in a Visible Light-Triggered Photocatalysis

Catalysts ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1500
Author(s):  
Sanjay Gopal Ullattil ◽  
Janez Zavašnik ◽  
Ksenija Maver ◽  
Matjaž Finšgar ◽  
Nataša Novak Tušar ◽  
...  
Keyword(s):  
Hydroxyl Radical ◽  
Hydroxyl Radicals ◽  
High Surface ◽  
High Surface Area ◽  
Reaction Rates ◽  
Trace Quantity ◽  
Absorption Of Light ◽  
Photocatalytic Reactions ◽  
Tio2 Nanostructures ◽  
High Calcination Temperature

The novelty of this work was to prepare a series of defect-rich colored TiO2 nanostructures, using a peroxo solvothermal-assisted, high-pressure nitrogenation method. Among these solids, certain TiO2 materials possessed a trace quantity of anatase–rutile heterojunctions, which are beneficial in obtaining high reaction rates in photocatalytic reactions. In addition, high surface area (above 100 m2/g), even when utilizing a high calcination temperature (500 °C), and absorption of light at higher wavelengths, due to the grey color of the synthesized titania, were observed as an added advantage for photocatalytic hydroxyl radical formation. In this work, we adopted a photoluminescent probe method to monitor the temporal evolution of hydroxyl radicals. As a result, promising hydroxyl radical formations were observed for all the colored samples synthesized at 400 and 500 °C, irrespective of the duration of calcination.

SEM analysis of the change in the reaction rates with deposit structures in the copper-iron cementation system

1978 ◽  
Vol 36 (1) ◽  
pp. 456-457
Author(s):  
V. Annamalai ◽  
L.E. Murr
Keyword(s):  
Structural Characteristics ◽  
Secondary Electron Emission ◽  
Copper Deposit ◽  
Reaction Rates ◽  
Sem Analysis ◽  
Experimental Conditions ◽  
Major Drawback ◽  
Emission Mode ◽  
Scrap Iron ◽  
Image Position

Economical recovery of copper metal from leach liquors has been carried out by the simple process of cementing copper onto a suitable substrate metal, such as scrap-iron, since the 16th century. The process has, however, a major drawback of consuming more iron than stoichiometrically needed by the reaction.Therefore, many research groups started looking into the process more closely. Though it is accepted that the structural characteristics of the resultant copper deposit cause changes in reaction rates for various experimental conditions, not many systems have been systematically investigated. This paper examines the deposit structures and the kinetic data, and explains the correlations between them.A simple cementation cell along with rotating discs of pure iron (99.9%) were employed in this study to obtain the kinetic results The resultant copper deposits were studied in a Hitachi Perkin-Elmer HHS-2R scanning electron microscope operated at 25kV in the secondary electron emission mode.

The Effects of Nitrogen on Electrical and Structural Properties in TaSixNy/SiO2/p-Si MOS Capacitors

2002 ◽  
Vol 716 ◽  
Author(s):  
You-Seok Suh ◽  
Greg Heuss ◽  
Jae-Hoon Lee ◽  
Veena Misra
Keyword(s):  
Structural Properties ◽  
Electron Spectroscopy ◽  
Oxygen Diffusion ◽  
Gate Dielectric ◽  
Barrier Properties ◽  
Reaction Rates ◽  
Cross Sectional ◽  
Mos Capacitors ◽  
Transmission Electron ◽  
Thermal Stability Of

AbstractIn this work, we report the effects of nitrogen on electrical and structural properties in TaSixNy /SiO2/p-Si MOS capacitors. TaSixNy films with various compositions were deposited by reactive sputtering of TaSi2 or by co-sputtering of Ta and Si targets in argon and nitrogen ambient. TaSixNy films were characterized by Rutherford backscattering spectroscopy and Auger electron spectroscopy. It was found that the workfunction of TaSixNy (Si>Ta) with varying N contents ranges from 4.2 to 4.3 eV. Cross-sectional transmission electron microscopy shows no indication of interfacial reaction or crystallization in TaSixNy on SiO2, resulting in no significant increase of leakage current in the capacitor during annealing. It is believed that nitrogen retards reaction rates and improves the chemical-thermal stability of the gate-dielectric interface and oxygen diffusion barrier properties.

Power Supply Overlaid Communication with Common Clock Delivery for Cooperative Motion Control

2011 ◽  
Vol E94-A (12) ◽  
pp. 2773-2775
Author(s):  
Fumikazu MINAMIYAMA ◽  
Hidetsugu KOGA ◽  
Kentaro KOBAYASHI ◽  
Masaaki KATAYAMA
Keyword(s):  
Motion Control ◽  
Power Supply ◽  
Cooperative Motion

Hydrostibination of Alkynes: A Radical Mechanism

2020 ◽  
Author(s):  
Josh MacMillan ◽  
Katherine Marczenko ◽  
Erin Johnson ◽  
Saurabh Chitnis
Keyword(s):  
Density Functional ◽  
Activation Barrier ◽  
Closed Shell ◽  
Reaction Rates ◽  
Radical Mechanism ◽  
Neutral Radical ◽  
Kinetic Isotope ◽  
Rate Limiting Step ◽  
Ionic Mechanisms ◽  
Terminal Acetylenes

The addition of Sb-H bonds to alkynes was reported recently as a new hydroelementation reaction that exclusively yields anti-Markovnikov <i>Z</i>-olefins from terminal acetylenes. We examine four possible mechanisms that are consistent with the observed stereochemical and regiochemical outcomes. A comprehensive analysis of solvent, substituent, isotope, additive, and temperature effects on hydrostibination reaction rates definitively refutes three ionic mechanisms involving closed-shell charged intermediates. Instead the data support a fourth pathway featuring neutral radical Sb<sup>II</sup> and Sb<sup>III</sup> intermediates. Density Functional Theory (DFT) calculations are consistent this model, predicting an activation barrier that is within 1 kcal mol<sup>-1</sup> of the experimental value (Eyring analysis) and a rate limiting step that is congruent with experimental kinetic isotope effect. We therefore conclude that hydrostibination of arylacetylenes is initiated by the generation of stibinyl radicals, which then participate in a cycle featuring Sb<sup>II</sup> and Sb<sup>III</sup> intermediates to yield the observed <i>Z</i>-olefins as products. This mechanistic understanding will enable rational evolution of hydrostibination as a methodology for accessing challenging products such as <i>E</i>-olefins.

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