scholarly journals Comparison of Material Activity and Selectivity in the Electrocatalytic Oxidation of Dibenzothiophene

2021 ◽  
Author(s):  
Victoria Kompanjiec ◽  
John R Swierk
Keyword(s):  
Water Oxidation ◽  
Electrocatalytic Oxidation ◽  
Oxidative Desulfurization ◽  
Oxidation Products ◽  
Faradaic Efficiency ◽  
Lower Activation ◽  
Bulk Electrolysis ◽  
Percent Conversion ◽  
Increasing Demand ◽  
Electrochemical Catalysts

Abstract There is an increasing demand for efficient methods to remove sulfur from oil products, such as oxidative desulfurization. In this work, a set of five materials (gold, glassy carbon, nickel, palladium and platinum) were evaluated as electrochemical catalysts for the oxidation of dibenzothiophene (DBT). Bulk electrolysis performed without water present, produced DBT dimer, while the addition of 2 M water, produced dibenzothiophene sulfoxide (DBTO), both more polar than DBT. LC-MS and NMR were used to characterize the oxidation products. Faradaic efficiencies ranged from 18.4–56.5% for DBT consumption without water present, and there was a correlation between higher rate constants, lower activation energies and more efficient DBT oxidation. With water present, selectivity for DBTO formation was highest using gold, with a Faradaic efficiency of 87.9%. Group ten metals demonstrated low Faradaic efficiencies due to competitive water oxidation. Though there were differences in the observed selectivity for DBT oxidation, all catalysts reduced the concentration of DBT in solution by similar amounts. Our findings indicate that the overall percent conversion does not give a complete picture of catalytic activity. Of the materials tested, gold was the most selective for oxidation to DBTO, with the presence of water improving the overall reaction activity.

scholarly journals Comparison of Material Activity and Selectivity in the Electrocatalytic Oxidation of Dibenzothiophene

2021 ◽  
Author(s):  
John Swierk ◽  
Victoria Kompanijec
Keyword(s):  
Water Oxidation ◽  
Oxidative Desulfurization ◽  
Cost Effective ◽  
Oxidation Products ◽  
Faradaic Efficiency ◽  
Cost Effective Method ◽  
Fuel Oils ◽  
Increasing Demand ◽  
Sulfur Containing ◽  
Electrochemical Catalysts

Due to adverse effects of sulfur-containing compounds present in fuel oils, there is an increasing demand for an efficient and cost-effective method of removing sulfur from oil products, such as oxidative desulfurization. In this work, a set of five materials (gold, glassy carbon, nickel, palladium and platinum) were evaluated as electrochemical catalysts for the oxidation of DBT. Electrolysis at 1.58 V was performed without water present (producing a dimer of DBT) and with the addition of 2 M water (producing DBTO). LC-MS and NMR were used to characterize the oxidation products. It was found that the Faradaic efficiencies ranged from 18.4 – 56.5% for consumption of DBT without water present and there was a correlation between higher rate constants, lower activation energies and more efficient DBT oxidation. After the addition of water, the formation of DBTO was found to have the highest selectivity when catalyzed by gold, with a Faradaic efficiency of 87.9%. The group ten metals demonstrated low Faradaic efficiencies due to the competitive water oxidation taking place. Though there were differences in the observed selectivity for DBT oxidation, all catalysts reduced the concentration of DBT in solution by similar amounts. Of the materials tested, gold served as the most selective for oxidation to DBTO, with the presence of water improving the overall reaction activity.

scholarly journals The effect of nanoparticulate PdO co-catalysts on the faradaic and light conversion efficiency of WO3 photoanodes for water oxidation

2021 ◽  
Author(s):  
Anna A. Wilson ◽  
Sacha Corby ◽  
Laia Francàs ◽  
James R. Durrant ◽  
Andreas Kafizas
Keyword(s):  
Conversion Efficiency ◽  
Water Oxidation ◽  
Faradaic Efficiency ◽  
Co Catalysts ◽  
Photocurrent Generation ◽  
Light Conversion Efficiency ◽  
Electron Extraction

PdO nanoparticles grown on the surface of nanostructured WO3 photoanodes dramatically increase the faradaic efficiency of water oxidation from 52% to 92%, whilst also enhancing photocurrent generation and electron extraction rates.

scholarly journals The effect of dihydroquercetin on the stability of consumer properties of chopped semi-finished meat

2021 ◽  
Vol 285 ◽  
pp. 05011
Author(s):  
N. N. Shagaeva ◽  
S. V. Kolobov ◽  
I. A. Zachesova
Keyword(s):  
Meat Products ◽  
Microbiological Quality ◽  
Negative Temperature ◽  
Acid Number ◽  
Oxidation Products ◽  
Raw Material ◽  
Experimental Sample ◽  
Quality Stability ◽  
Increasing Demand ◽  
The Stability

The steadily increasing demand for semi-finished meat products is provided by the constantly expanding product range and improving its quality. In turn, quality stability is an important criterion for increasing sales. The article presents data on the effect of a natural antioxidant-dihydroquercetin on the stability of consumer properties of chopped semi-finished moose meat with the addition of beet fiber when stored at a negative temperature for 216 days. Dihydroquercetin was added in an amount of 0.05% by weight of the raw material. In the course of the work, generally accepted methods of studying organoleptic and microbiological quality indicators were used. The degree of oxidative deterioration of the product was checked by determining the acid, peroxide and thiobarbituric numbers. The conducted studies allowed us to conclude that the use of this food additive allows us to preserve the organoleptic and microbiological properties of the semi-finished product for a longer period by inhibiting the formation of oxidation products. The use of dihydroquercetin contributed to a decrease in the experimental sample of the semi-finished product on day 216 of the peroxide and acid number by 2 times, and the thiobarbituric number by 1.8 times in relation to the control. Thus, by reducing the oxidative damage of the semi-finished product, it is possible to influence its characteristics during storage.

scholarly journals Highly active oxygen evolution integrated with efficient CO2 to CO electroreduction

2019 ◽  
Vol 116 (48) ◽  
pp. 23915-23922 ◽  
Author(s):  
Yongtao Meng ◽  
Xiao Zhang ◽  
Wei-Hsuan Hung ◽  
Junkai He ◽  
Yi-Sheng Tsai ◽  
...  
Keyword(s):  
Oxygen Evolution ◽  
Water Oxidation ◽  
Iron Hydroxide ◽  
Fuel Efficiency ◽  
Cell Voltage ◽  
Electrical Energy ◽  
Reduction Reaction ◽  
Faradaic Efficiency ◽  
Nickel Iron ◽  
Highly Active

Electrochemical reduction of CO2 to useful chemicals has been actively pursued for closing the carbon cycle and preventing further deterioration of the environment/climate. Since CO2 reduction reaction (CO2RR) at a cathode is always paired with the oxygen evolution reaction (OER) at an anode, the overall efficiency of electrical energy to chemical fuel conversion must consider the large energy barrier and sluggish kinetics of OER, especially in widely used electrolytes, such as the pH-neutral CO2-saturated 0.5 M KHCO3. OER in such electrolytes mostly relies on noble metal (Ir- and Ru-based) electrocatalysts in the anode. Here, we discover that by anodizing a metallic Ni–Fe composite foam under a harsh condition (in a low-concentration 0.1 M KHCO3 solution at 85 °C under a high-current ∼250 mA/cm2), OER on the NiFe foam is accompanied by anodic etching, and the surface layer evolves into a nickel–iron hydroxide carbonate (NiFe-HC) material composed of porous, poorly crystalline flakes of flower-like NiFe layer-double hydroxide (LDH) intercalated with carbonate anions. The resulting NiFe-HC electrode in CO2-saturated 0.5 M KHCO3 exhibited OER activity superior to IrO2, with an overpotential of 450 and 590 mV to reach 10 and 250 mA/cm2, respectively, and high stability for >120 h without decay. We paired NiFe-HC with a CO2RR catalyst of cobalt phthalocyanine/carbon nanotube (CoPc/CNT) in a CO2 electrolyzer, achieving selective cathodic conversion of CO2 to CO with >97% Faradaic efficiency and simultaneous anodic water oxidation to O2. The device showed a low cell voltage of 2.13 V and high electricity-to-chemical fuel efficiency of 59% at a current density of 10 mA/cm2.

Function-switchable metal/semiconductor junction enables efficient photocatalytic overall water splitting with selective water oxidation products

2020 ◽  
Vol 65 (16) ◽  
pp. 1389-1395 ◽  
Author(s):  
Daixing Wei ◽  
Yubo Tan ◽  
Yiqing Wang ◽  
Tingting Kong ◽  
Shaohua Shen ◽  
...  
Keyword(s):  
Water Splitting ◽  
Water Oxidation ◽  
Oxidation Products ◽  
Overall Water Splitting ◽  
Semiconductor Junction

scholarly journals Crossing the bridge from molecular catalysis to a heterogenous electrode in electrocatalytic water oxidation

2019 ◽  
Vol 116 (23) ◽  
pp. 11153-11158 ◽  
Author(s):  
Lei Wu ◽  
Animesh Nayak ◽  
Jing Shao ◽  
Thomas J. Meyer
Keyword(s):  
Tin Oxide ◽  
Indium Tin Oxide ◽  
Water Oxidation ◽  
Polymer Network ◽  
Surface Binding ◽  
Faradaic Efficiency ◽  
Electrode Surfaces ◽  
Electrolytic Cells ◽  
Conductive Substrates ◽  
Limited Surface

Significant progress has been made in designing single-site molecular Ru(II)-polypyridyl-aqua catalysts for homogenous catalytic water oxidation. Surface binding and transfer of the catalytic reactivity onto conductive substrates provides a basis for heterogeneous applications in electrolytic cells and dye-sensitized photoelectrosynthesis cells (DSPECs). Earlier efforts have focused on phosphonic acid (-PO3H2) or carboxylic acid (-CO2H) bindings on oxide surfaces. However, issues remain with limited surface stabilities, especially in aqueous solutions at higher pH under conditions that favor water oxidation by reducing the thermodynamic barrier and accelerating the catalytic rate using atom-proton transfer (APT) pathways. Here, we address the problem by combining silane surface functionalization and surface reductive electropolymerization on mesoporous, nanofilms of indium tin oxide (ITO) on fluorine-doped tin oxide (FTO) substrates (FTO|nanoITO). FTO|nanoITO electrodes were functionalized with vinyltrimethoxysilane (VTMS) to introduce vinyl groups on the electrode surfaces by silane attachment, followed by surface electropolymerization of the vinyl-derivatized complex, [RuII(Mebimpy)(dvbpy)(OH2)]2+ (12+; Mebimpy: 2,6-bis(1-methyl-1H-benzo[d]imidazol-2-yl)pyridine; dvbpy: 5,5′-divinyl-2,2′-bipyridine), in a mechanism dominated by a grafting-through method. The surface coverage of catalyst 12+ was controlled by the number of electropolymerization cycles. The combined silane attachment/cross-linked polymer network stabilized 12+ on the electrode surface under a variety of conditions especially at pH > ∼6. Surface-grafted poly12+ was stable toward redox cycling at pH ∼ 7.5 over an ∼4-h period. Sustained heterogeneous electrocatalytic water oxidation by the electrode gave steady-state currents for at least ∼6 h with a Faradaic efficiency of ∼68% for O2 production.

Electrocatalytic oxidation of water by a self-assembled oxovanadium(iv) complex modified gold electrode

2015 ◽  
Vol 5 (12) ◽  
pp. 5100-5104 ◽  
Author(s):  
Koushik Barman ◽  
Sk Jasimuddin
Keyword(s):  
Water Oxidation ◽  
Electrocatalytic Activity ◽  
Gold Electrode ◽  
Electrocatalytic Oxidation ◽  
Neutral Ph ◽  
Self Assembled

An oxovanadium(iv) complex modified gold electrode showed efficient electrocatalytic activity towards water oxidation at neutral pH.

scholarly journals Oxidative Desulfurization of Dibenzothiophene Using Dawson Type Heteropoly Compounds/Tantalum as Catalyst

2018 ◽  
Vol 16 (1) ◽  
pp. 105 ◽  
Author(s):  
Risfidian Mohadi ◽  
Lusi Teresia ◽  
Najma Annuria Fithri ◽  
Aldes Lesbani ◽  
Nurlisa Hidayati
Keyword(s):  
Catalytic Activity ◽  
Vibration Spectrum ◽  
Oxidative Desulfurization ◽  
Heteropoly Compounds ◽  
Atmospheric Conditions ◽  
N2 Adsorption ◽  
Fresh Catalyst ◽  
Wet Impregnation ◽  
Percent Conversion ◽  
Adsorption Desorption

Catalyst (NH4)6[b-P2W18O62]/Ta has been synthesized by simple wet impregnation at 30-40 °C under atmospheric conditions using Dawson type polyoxometalate (NH4)6[b-P2W18O62] and tantalum. The catalyst was characterized by FTIR spectrophotometer, XRD, SEM, and N2 adsorption desorption methods. FTIR spectrum of (NH4)6[b-P2W18O62]/Ta showed that Dawson type polyoxometalate (NH4)6[b-P2W18O62] and Ta was successfully impregnated which was indicated by vibration spectrum at wavenumber of 900-1100 cm-1 for polyoxometalate and 550 cm-1 for Ta. The surface area of the (NH4)6[b-P2W18O62]/Ta after impregnation was higher than (NH4)6[b-P2W18O62]•nH2O and its morphology was found to be uniform. The catalytic activity of (NH4)6[b-P2W18O62]/Ta toward desulfurization of dibenzothiophene was three times higher than the original catalyst of (NH4)6[b-P2W18O62]•nH2O without impregnation. The catalytic regeneration test of catalyst (NH4)6[b-P2W18O62]/Ta showed that the catalytic activity for first regeneration of catalyst has similar catalytic activity with the fresh catalyst without loss of catalytic activity indicated by almost similar percent conversion.

Decoupling Hydrogen Production and Water Oxidation in a Hybrid Solar-Driven Vanadium Redox Cell Supported By a Bipolar Membrane with Earth-Abundant Catalysts

2018 ◽  
Vol MA2018-01 (31) ◽  
pp. 1864-1864
Author(s):  
Chengxiang("CX") Xiang
Keyword(s):  
Water Splitting ◽  
Water Oxidation ◽  
Cathode Surface ◽  
Hydrogen Generation ◽  
Anode Surface ◽  
Faradaic Efficiency ◽  
Solar Water ◽  
Solar Water Splitting ◽  
Hydrogen Molecules ◽  
Vanadium Redox

Renewable hydrogen produced by solar water-splitting has the potential to balance the intermittent nature of the sunlight and support grid-scale energy storage. In a solar-driven water-splitting device, the cathode surface and the anode surface involve hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), which are tightly coupled with each other, that is, whenever one oxygen molecule was produced at the cathode surface, two hydrogen molecules were produced at the anode surface at the same time. In this talk, I will show some recent results on an alternative approach to solar water-splitting, where the electron and proton generated at OER was used to charge an aqueous vanadium solution in a 2.0 M sulfuric acid (pH = -0.16) electrolyte with near unity Faradaic efficiency, rather than being used directly to produce hydrogen at the cathode. The produced V2+ species in the cathode chamber was then passed through a MoCx based catalyst to produce hydrogen and to re-generate V3+ for the subsequent reduction, with an average hydrogen generation efficiency of 85% at different depths of charging. Coupled to a solar tracker, the solar-driven vanadium redox cell was charged outdoors under real-world illumination during the day and discharged at night to produce hydrogen with a daily average solar to hydrogen (STH) conversion efficiency of 5.8%.

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