Electrochemical and Computational Insights into the Reduction of [Fe2(CO)6{µ-(SCH2)2GeMe2}] Hydrogenase H-Cluster Mimic

The electrochemical reduction of the complex [Fe2(CO)6{µ-(SCH2)2GeMe2}] (1) under N2 and CO is reported applying cyclic voltammetry. Reduction of complex 1 in CO saturated solutions prevents the possible release of CO from the dianion 12−, while the latter reacts with additional CO forming a spectroscopically uncharacterized product P1. This product undergoes a reversible redox process at E1/2 = −0.70 V (0.2 V∙s−1). In this report, the structure of the neutral complex 1, isomers of dianionic form of 1, and P1 are described applying DFT computations. Furthermore, we propose reaction pathways for H2 production on the basis of the cyclic voltammetry of complex 1 in presence of the strong acid CF3SO3H.

Download Full-text

Voltammetric Sensors Based on Nanomaterials for Detection of Caffeic Acid in Food Supplements

Chemosensors ◽

10.3390/chemosensors8020041 ◽

2020 ◽

Vol 8 (2) ◽

pp. 41 ◽

Cited By ~ 5

Author(s):

Alexandra Bounegru ◽

Constantin Apetrei

Keyword(s):

Cyclic Voltammetry ◽

Caffeic Acid ◽

Carbon Nanofiber ◽

Food Supplements ◽

Redox Process ◽

Sensor Performance ◽

Reversible Redox ◽

Printed Sensors ◽

Sensitive Sensor ◽

Screen Printed

Caffeic acid may be accurately detected in food supplements by using cyclic voltammetry and carbon screen-printed sensors modified with various nanomaterials. Sensor characterization by cyclic voltammetry in reference solutions has shown that carbon nanotubes or carbon nanofibers significantly improve the sensor response in terms of sensitivity and reversibility. Screen-printed sensors were then used in order to study the electrochemical behavior of caffeic acid in aqueous solution at pH 3.6. A redox process was observed in all cases, which corresponds to a reversible redox process involving the transfer of two electrons and two protons. The role of nanomaterials in the increment of sensor performance characteristics was evidenced. Calibration curves were developed for each sensor, and the detection (LOD) and quantification (LOQ) limits were calculated. Low LOD and LOQ values were obtained, in the 10−7 to 10−9 M range, which demonstrates that the method is feasible for quantification of caffeic acid in real samples. Caffeic acid was quantitatively determined in three food supplements using the most sensitive sensor, namely the carbon nanofiber sensor. The Folin–Ciocalteu spectrophotometric assay was used to validate the results obtained with the sensor. The results obtained by using the voltammetric method were consistent with those obtained by using the spectrophotometric method, with no statistically significant differences between the results obtained at 95% confidence level.

Download Full-text

Photochemical and Electrochemical Reduction of Carbon Dioxide Catalyzed by a Polyoxometalate-Organic Photosensitizer Complex

10.26434/chemrxiv.7177892 ◽

2018 ◽

Author(s):

Chandan Dey ◽

Ronny Neumann

Keyword(s):

Carbon Dioxide ◽

Cyclic Voltammetry ◽

Formic Acid ◽

Electrochemical Reduction ◽

Mass Spectroscopy ◽

Photochemical Reactions ◽

Reducing Agent ◽

Covalent Attachment ◽

Hybrid Complex ◽

Open Face

A manganese substituted Anderson type polyoxometalate, [MnMo6O24]9-, tethered with an anthracene photosensitizer was prepared and used as catalyst for CO2 reduction. The polyoxometalate-photosensitizer hybrid complex, obtained by covalent attachment of the sensitizer to only one face of the planar polyoxometalate, was characterized by NMR, IR and mass spectroscopy. Cyclic voltammetry measurements show a catalytic response for the reduction of carbon dioxide, thereby suggesting catalysis at the manganese site on the open face of the polyoxometalate. Controlled potentiometric electrolysis showed the reduction of CO2 to CO with a TOF of ~15 sec-1. Further photochemical reactions showed that the polyoxometalate-anthracene hybrid complex was active for the reduction of CO2 to yield formic acid and/or CO in varying amounts dependent on the reducing agent used. Control experiments showed that the attachment of the photosensitizer to [MnMo6O24]9- is necessary for photocatalysis.<div> </div>

Download Full-text

The Effect of Ni Addition onto a Cu-Based Ternary Support on the H2 Production over Glycerol Steam Reforming Reaction

Nanomaterials ◽

10.3390/nano8110931 ◽

2018 ◽

Vol 8 (11) ◽

pp. 931 ◽

Cited By ~ 15

Author(s):

Kyriaki Polychronopoulou ◽

Nikolaos Charisiou ◽

Kyriakos Papageridis ◽

Victor Sebastian ◽

Steven Hinder ◽

...

Keyword(s):

Sol Gel ◽

Strong Acid ◽

H2 Production ◽

Impregnation Method ◽

Reaction Products ◽

Cu Content ◽

Ni Addition ◽

Support Matrix ◽

Temperature Programmed ◽

H2 Yield

In the present study, Ni/Ce-Sm-xCu (x = 5, 7, 10 at.%) catalysts were prepared using microwave radiation coupled with sol-gel and followed by wetness impregnation method for the Ni incorporation. Highly dispersed nanocrystallites of CuO and NiO on the Ce-Sm-Cu support were found. Increase of Cu content seems to facilitate the reducibility of the catalyst according to the H2 temperature-programmed reduction (H2-TPR). All the catalysts had a variety of weak, medium and strong acid/basic sites that regulate the reaction products. All the catalysts had very high XC3H8O3 for the entire temperature (400–750 °C) range; from ≈84% at 400 °C to ≈94% at 750 °C. Ni/Ce-Sm-10Cu catalyst showed the lowest XC3H8O3-gas implying the Cu content has a detrimental effect on performance, especially between 450–650 °C. In terms of H2 selectivity (SH2) and H2 yield (YH2), both appeared to vary in the following order: Ni/Ce-Sm-10Cu > Ni/Ce-Sm-7Cu > Ni/Ce-Sm-5Cu, demonstrating the high impact of Cu content. Following stability tests, all the catalysts accumulated high amounts of carbon, following the order Ni/Ce-Sm-5Cu < Ni/Ce-Sm-7Cu < Ni/Ce-Sm-10Cu (52, 65 and 79 wt.%, respectively) based on the thermogravimetric analysis (TGA) studies. Raman studies showed that the incorporation of Cu in the support matrix controls the extent of carbon graphitization deposited during the reaction at hand.

Download Full-text

A study on maxima and inverted peaks in cyclic voltammetry. Electrochemical reduction of pyridine-4-aldoxime at an HMDE

Journal of Electroanalytical Chemistry ◽

10.1016/s0022-0728(01)00653-2 ◽

2001 ◽

Vol 517 (1-2) ◽

pp. 15-19 ◽

Cited By ~ 6

Author(s):

A.J. Roman ◽

J.M. Sevilla ◽

T. Pineda ◽

M. Blázquez

Keyword(s):

Cyclic Voltammetry ◽

Electrochemical Reduction

Download Full-text

Interaction between Binuclear Copper(I) Complexes and the Dioxygen Molecule Investigated by Electrochemical Methods

Zeitschrift für Naturforschung B ◽

10.1515/znb-1992-0120 ◽

1992 ◽

Vol 47 (1) ◽

pp. 109-114 ◽

Cited By ~ 2

Author(s):

Yuzo Nishida ◽

Izumi Watanabe ◽

Kei Unoura

Keyword(s):

Cyclic Voltammetry ◽

Thin Layer ◽

Electrochemical Reduction ◽

High Reactivity ◽

Electrochemical Methods ◽

Tridentate Ligand ◽

Cyclic Voltammograms ◽

Binuclear Copper ◽

Alkyl Chains ◽

Binucleating Ligands

The cyclic voltammograms of some binuclear copper(II) compounds with binucleating ligands where two molecules of tridentate ligand, N, N -bis(benzimidazol-2-ylmethyl)amine are linked by several alkyl chains, were measured under both argon and dioxygen. The results demonstrate that the binuclear copper(I) species produced by electrochemical reduction exhibit high reactivity towards dioxygen, while the reaction of the corresponding mononuclear species with oxygen is very slow. Thin-layer coulometry ([binuclear copper(I)]/[O2] = 0.47 - 10.6) and thin-layer cyclic voltammetry ([binuclear copper(I)]/[O2] = 4.3 - 10.6 ) revealed that two molecules of the binuclear copper(I) species react with one molecule of dioxygen.

Download Full-text

Clam-shaped cyclam-functionalized porphyrin for electrochemical reduction of carbon dioxide

Journal of Porphyrins and Phthalocyanines ◽

10.1142/s1088424619500548 ◽

2019 ◽

Vol 23 (04n05) ◽

pp. 453-461

Author(s):

Sumana Tawil ◽

Hathaichanok Seelajaroen ◽

Amorn Petsom ◽

Niyazi Serdar Sariciftci ◽

Patchanita Thamyongkit

Keyword(s):

Carbon Dioxide ◽

Carbon Monoxide ◽

Cyclic Voltammetry ◽

Catalytic Activity ◽

Electrochemical Reduction ◽

Target Compound ◽

Faradaic Efficiency ◽

Controlled Potential Electrolysis ◽

Improved Stability ◽

Controlled Potential

A clam-shaped molecule comprising a Zn(II)-porphyrin and a Zn(II)-cyclam is synthesized and characterized. Its electrochemical behavior and catalytic activity for homogeneous electrochemical reduction of carbon dioxide (CO[Formula: see text] are investigated by cyclic voltammetry and compared with those of Zn(II)-meso-tetraphenylporphyrin and Zn(II)-cyclam. Under N2-saturated conditions, cyclic voltammetry of the featured complex has characteristics of its two constituents, but under CO2-saturated conditions, the target compound exhibits significant current enhancement. Iterative reduction under electrochemical conditions indicated the target compound has improved stability relative to Zn(II)-cyclam. Controlled potential electrolysis demonstrates that, without addition of water, methane (CH[Formula: see text] is the only detectable product with 1% Faradaic efficiency (FE). The formation of CH4 is not observed under the catalysis of the Zn(II)-porphyrin benchmark compound, indicating that the CO2-capturing function of the Zn(II)-cyclam unit contributes to the catalysis. Upon addition of 3% v/v water, the electrochemical reduction of CO2 in the presence of the target compound gives carbon monoxide (CO) with 28% FE. Dominance of CO formation under these conditions suggests enhancement of proton-coupled reduction. Integrated action of these Zn(II)-porphyrin and Zn(II)-cyclam units offers a notable example of a molecular catalytic system where the cyclam ring captures and brings CO2 into the proximity of the porphyrin catalysis center.

Download Full-text

The effect of strong acid on the reactions of hydrogen and oxygen on the noble metals. A study using cyclic voltammetry and a new teflon electrode holder

Journal of Electroanalytical Chemistry ◽

10.1016/s0022-0728(72)80152-9 ◽

1972 ◽

Vol 39 (2) ◽

pp. 275-286 ◽

Cited By ~ 95

Author(s):

Andrew Capon ◽

Roger Parsons

Keyword(s):

Cyclic Voltammetry ◽

Noble Metals ◽

Strong Acid ◽

Electrode Holder

Download Full-text

Synthesis and Photoelectric Properties of a Novel Polymerizable Perylene Diimide Electron Acceptor Material

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.651.97 ◽

2013 ◽

Vol 651 ◽

pp. 97-102

Author(s):

Si Li Yi ◽

Qing Xu

Keyword(s):

Cyclic Voltammetry ◽

1H Nmr ◽

Electron Acceptor ◽

Perylene Diimide ◽

Absorption Bands ◽

Broad Absorption ◽

Chemical Structures ◽

Photoelectric Properties ◽

Reversible Redox ◽

Ft Ir

A novel polymerizable perylene diimide electron acceptor 1,7-bis(N,N-bis(4-methoxy phenyl)aniline)-N-(3-(2-ethylhexoxy)propylamide)-N-hexyl-perylene diimide acrylate (PDA) have been synthesized, and the chemical structures are conﬁrmed by 1H NMR and FT-IR. The PDA shows broad absorption bands in 400–850 nm, and the optical bandgap is calculated to be 1.45 eV. Cyclic voltammetry results conﬁrm that PDA display a couple of reversible redox peaks, the LUMO and HOMO levels of PDA were calculated as -3.82 eV and -5.16 eV, respectively.

Download Full-text

High-Temperature (1700–1800°C) Electrochemical Preparation of Metallic Ti from Rutile: A Pathway of Step-by-Step Electrodeoxidization

ISRN Metallurgy ◽

10.1155/2013/808413 ◽

2013 ◽

Vol 2013 ◽

pp. 1-6

Author(s):

Fanke Meng ◽

Huimin Lu

Keyword(s):

Cyclic Voltammetry ◽

High Temperature ◽

Electrochemical Reduction ◽

High Temperatures ◽

Metallic Titanium ◽

Reduction Procedure ◽

Electrochemical Preparation ◽

Electrolytic Potential

The mechanism of producing metallic titanium by electrochemically reducing rutile (TiO2) at high temperatures was studied. First, the oxygen was successfully electroremoved from TiO2 at temperatures 1700, 1750, and 1800°C in molten CaF2 under a stable electrolytic potential of 2.5 V. Second, the electrodeoxidization process was studied with cyclic voltammetry (CV) tests at 1750°C. It was found that the electrochemical reduction for preparing metallic Ti from TiO2 at the high temperatures can be divided into several steps. In other words, the oxygen in TiO2 was electro-removed as a step-by-step pathway (TiO2→Ti4O7→Ti3O5/Ti2O3→TiO→Ti) at different electrolytic potentials. It unraveled the mechanism of electrochemical reduction of TiO2 at the high temperatures, which is helpful for monitoring the reduction procedure.

Download Full-text