scholarly journals In Situ Determination of pH at Nanostructured Carbon Electrodes Using IR Spectroscopy

Materials ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4044
Author(s):  
Lolade Bamgbelu ◽  
Katherine B Holt
Keyword(s):  
Ir Spectroscopy ◽  
Redox Reactions ◽  
Ph Change ◽  
Ph Changes ◽  
Electrode Surfaces ◽  
Phosphate Ions ◽  
Phosphate Species ◽  
Analytical Importance ◽  
Electrode Interface

Changes in pH at electrode surfaces can occur when redox reactions involving the production or consumption of protons take place. Many redox reactions of biological or analytical importance are proton-coupled, resulting in localized interfacial pH changes as the reaction proceeds. Other important electrochemical reactions, such as hydrogen and oxygen evolution reactions, can likewise result in pH changes near the electrode. However, it is very difficult to measure pH changes located within around 100 µm of the electrode surface. This paper describes the use of in situ attenuated total reflectance (ATR) infrared (IR) spectroscopy to determine the pH of different solutions directly at the electrode interface, while a potential is applied. Changes in the distinctive IR bands of solution phosphate species are used as an indicator of pH change, given that the protonation state of the phosphate ions is pH-dependent. We found that the pH at the surface of an electrode modified with carbon nanotubes can increase from 4.5 to 11 during the hydrogen evolution reaction, even in buffered solutions. The local pH change accompanying the hydroquinone–quinone redox reaction is also determined.

Development and validation of an in situ and real-time quantification method for bicarbonate, carbonate and orthophosphate ions by ATR FT-IR spectroscopy in aqueous solutions

The Analyst ◽  
2018 ◽  
Vol 143 (18) ◽  
pp. 4387-4393 ◽  
Author(s):  
Pierre-Olivier Morisset ◽  
Jonathan Gagnon ◽  
Réjean Tremblay ◽  
Jean-Sébastien Deschênes
Keyword(s):  
Ir Spectroscopy ◽  
Real Time ◽  
Inorganic Carbon ◽  
Bioprocess Monitoring ◽  
Quantification Method ◽  
Phosphate Ions ◽  
Ft Ir ◽  
Development And Validation ◽  
Ft Ir Spectroscopy

An in situ real-time quantification method for inorganic carbon and phosphate ions in water using ATR FT-IR suitable for bioprocess monitoring is described.

In Situ Analytical Electron Microscopy Studies of Redox Reactions at a YSZ/Pt Interface

2012 ◽  
Vol 18 (3) ◽  
pp. 538-544 ◽  
Author(s):  
Amir Hossein Tavabi ◽  
Shigeo Arai ◽  
Takayoshi Tanji
Keyword(s):  
Electron Microscopy ◽  
Redox Reactions ◽  
Elevated Temperatures ◽  
Analytical Electron Microscopy ◽  
Electron Holography ◽  
Analytical Electron ◽  
Electrode Interface ◽  
Host Cation ◽  
Reduced State

AbstractRedox reactions were studied at a single yttria-stabilized zirconia (YSZ)/Pt electrode interface, in parallel with pure YSZ with no catalyst electrode, by in situ analytical electron microscopy at elevated temperatures and in an oxygen atmosphere. In situ electron holography showed that the oxide underwent reduction at elevated temperatures in a vacuum and was consequently reoxidized upon exposure to an oxygen flux at the same temperature. In situ energy loss spectroscopy measurements were in agreement with in situ electron holography observations and indicated that the oxidation state of the host cation zirconium was altered in the reduced state of the YSZ to the metastable state Zr3+.

The Nature of Chemisorbed CO2 in Zeolite A

2019 ◽  
Author(s):  
Przemyslaw Rzepka ◽  
Zoltán Bacsik ◽  
Andrew J. Pell ◽  
Niklas Hedin ◽  
Aleksander Jaworski
Keyword(s):  
Solid State ◽  
Ir Spectroscopy ◽  
Quantum Chemical Calculations ◽  
Quantum Chemical ◽  
Surface Coverage ◽  
Gas Mixtures ◽  
Mas Nmr ◽  
Significant Fraction ◽  
Zeolite A

Formation of CO<sub>3</sub><sup>2-</sup> and HCO<sub>3</sub><sup>-</sup> species without participation of the framework oxygen atoms upon chemisorption of CO<sub>2</sub> in zeolite |Na<sub>12</sub>|-A is revealed. The transfer of O and H atoms is very likely to have proceeded via the involvement of residual H<sub>2</sub>O or acid groups. A combined study by solid-state <sup>13</sup>C MAS NMR, quantum chemical calculations, and <i>in situ</i> IR spectroscopy showed that the chemisorption mainly occurred by the formation of HCO<sub>3</sub><sup>-</sup>. However, at a low surface coverage of physisorbed and acidic CO<sub>2</sub>, a significant fraction of the HCO<sub>3</sub><sup>-</sup> was deprotonated and transformed into CO<sub>3</sub><sup>2-</sup>. We expect that similar chemisorption of CO<sub>2</sub> would occur for low-silica zeolites and other basic silicates of interest for the capture of CO<sub>2</sub> from gas mixtures.

Catalytic activity of rhodium(I) complexes containing (ω-trimethylsilylalkyl)diphenylphosphines

1980 ◽  
Vol 45 (8) ◽  
pp. 2219-2223 ◽  
Author(s):  
Marie Jakoubková ◽  
Martin Čapka
Keyword(s):  
Catalytic Activity ◽  
Nmr Spectroscopy ◽  
Ir Spectroscopy ◽  
Electron Density ◽  
Phosphorus Atom ◽  
Proton Acceptor ◽  
Trimethylsilyl Group ◽  
Kinetics Of

Kinetics of homogenous hydrogenation of 1-heptene catalysed by rhodium(I) complexes prepared in situ from μ,μ'-dichloro-bis(cyclooctenerhodium) and phosphines of the type RP(C6H5)2 (R = -CH3, -(CH2)nSi(CH3)3; n = 1-4) have been studied. The substitution of the ligands by the trimethylsilyl group was found to increase significantly the catalytic activity of the complexes. The results are discussed in relation to the electron density on the phosphorus atom determined by 31P NMR spectroscopy and to its proton acceptor ability determined by IR spectroscopy.

scholarly journals A Novel Cobalt Metallopolymer with Redox-Matched Conjugated Organic Backbone via Electropolymerization of a Readily Available N4 Cobalt Complex

Polymers ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1667
Author(s):  
Mikhail Karushev
Keyword(s):  
Redox Reactions ◽  
Repeat Unit ◽  
Cobalt Complex ◽  
Radical Cations ◽  
Electrochemical Quartz Crystal Microbalance ◽  
Practical Applications ◽  
Sensing Applications ◽  
Novel Approach ◽  
Redox Switching

Fast and reversible cobalt-centered redox reactions in metallopolymers are the key to using these materials in energy storage, electrocatalytic, and sensing applications. Metal-centered electrochemical activity can be enhanced via redox matching of the conjugated organic backbone and cobalt centers. In this study, we present a novel approach to redox matching via modification of the cobalt coordination site: a conductive electrochemically active polymer was electro-synthesized from [Co(Amben)] complex (Amben = N,N′-bis(o-aminobenzylidene)ethylenediamine) for the first time. The poly-[Co(Amben)] films were investigated by cyclic voltammetry, electrochemical quartz crystal microbalance (EQCM), in situ UV‑vis-NIR spectroelectrochemistry, and in situ conductance measurements between −0.9 and 1.3 V vs. Ag/Ag+. The polymer displayed multistep redox processes involving reversible transfer of the total of 1.25 electrons per repeat unit. The findings indicate consecutive formation of three redox states during reversible electrochemical oxidation of the polymer film, which were identified as benzidine radical cations, Co(III) ions, and benzidine di-cations. The Co(II)/Co(III) redox switching is retained in the thick polymer films because it occurs at potentials of high polymer conductivity due to the optimum redox matching of the Co(II)/Co(III) redox pair with the organic conjugated backbone. It makes poly-[Co(Amben)] suitable for various practical applications based on cobalt-mediated redox reactions.

In Situ IR Spectroscopy for Following the Copolymerization of CO2and Epoxides

2014 ◽  
Vol 86 (9) ◽  
pp. 1627-1628
Author(s):  
K. Böhm ◽  
W. Leitner ◽  
T. E. Müller
Keyword(s):  
Ir Spectroscopy ◽  
In Situ Ir ◽  
In Situ Ir Spectroscopy

scholarly journals An in situ study of reconstructed gold electrode surfaces by second harmonic generation

1989 ◽  
Vol 163 (2-3) ◽  
pp. 123-128 ◽  
Author(s):  
A. Friedrich ◽  
B. Pettinger ◽  
D.M. Kolb ◽  
G. Lüpke ◽  
R. Steinhoff ◽  
...  
Keyword(s):  
Second Harmonic Generation ◽  
Harmonic Generation ◽  
Gold Electrode ◽  
Second Harmonic ◽  
Electrode Surfaces ◽  
In Situ Study
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