The importance of identifying the true catalyst when using Randles-Sevcik equation to calculate turnover frequency

Abdi, Zahra; Vandichel, Matthias; Sologubenko, Alla S.; Willinger, Marc Georg; Shen, Jian Ren; Allakhverdiev, Suleyman I.; Najafpour, Mohammad Mahdi

doi:10.1016/j.ijhydene.2021.09.039

Cited by 44 publications

(16 citation statements)

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“…The Randles–Sevcik equation describes the influence of the scan rate against peak intensity. According to this equation, the cathodic peak intensity (I pc , A) is the product of 268.600, the number of electrons transferred in redox processes (n 3/2 ), the area of the electrode active surface (A/cm 2 ), the diffusion coefficient (D, cm 2 ·s −1 ), the concentration (C, mol·cm −3 ), and the scan rate (v 1/2 , V·s −1 ) [ 38 ].…”

Section: Resultsmentioning

confidence: 99%

Quantification of Tyrosine in Pharmaceuticals with the New Biosensor Based on Laccase-Modified Polypyrrole Polymeric Thin Film

Dinu¹,

Apetrei²

2022

Polymers

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Stress, a state of body tension, sometimes caused by increased levels of tyrosine (Tyr) in the body, can lead to serious illnesses such as depression, irritability, anxiety, damage to the thyroid gland, and insomnia. The body can be provided with an adequate concentration of tyrosine by taking pharmaceutical products or by dietary intake. Therefore, this study presents the development of a new enzyme sensor for the quantification of Tyr in pharmaceuticals. A screen-printed carbon electrode (SPCE) was modified with the conductive polymer (CP) polypyrrole (PPy) doped with hexacyanoferrate (II) anion (FeCN), the polymer having been selected for its excellent properties, namely, permeability, conductivity, and stability. The enzyme laccase (Lacc) was subsequently immobilized in the polymer matrix and cross-linked with glutaraldehyde, as this enzyme is a thermostable catalyst, greatly improving the performance of the biosensor. The electrochemical method of analysis of the new device, Lacc/PPy/FeCN/SPCE, was cyclic voltammetry (CV), and chronoamperometry (CA) contributed to the study of changes in the biosensor with doped PPy. CV measurements confirmed that the Lacc/PPy/FeCN/SPCE biosensor is a sensitive and efficient platform for Tyr detection. Thus, this enzyme sensor showed a very low limit of detection (LOD) of 2.29 × 10−8 M, a limit of quantification (LOQ) of 7.63 × 10−8 M, and a very high sensitivity compared to both devices reported in the literature and the PPy/FeCN/SPCE sensor. Quantitative determination in pharmaceuticals was performed in L-Tyr solution of different concentrations ranging from 0.09 to 7 × 10−6 M. Validation of the device was performed by infrared spectrometry (FT-IR) on three pharmaceuticals from different manufacturers and with different Tyr concentrations.

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Section: Resultsmentioning

confidence: 99%

Quantification of Tyrosine in Pharmaceuticals with the New Biosensor Based on Laccase-Modified Polypyrrole Polymeric Thin Film

Dinu¹,

Apetrei²

2022

Polymers

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“…In the presence of many metal complexes, an extremely high TOF (10−1400 s −1 ) is calculated for WOR. 29 Using several methods in CV, we demonstrated that in the anodic sweep metal oxides were formed on the surface of the electrode before and during WOR. 29 However, in the cathodic sweep, the resulting metal oxides were dissolved.…”

Section: ■ Conversion Of Mn Complexes To Mn Oxidementioning

confidence: 95%

“…29 Using several methods in CV, we demonstrated that in the anodic sweep metal oxides were formed on the surface of the electrode before and during WOR. 29 However, in the cathodic sweep, the resulting metal oxides were dissolved. This observation is remarkable and indicates that postcharacterization methods may leave a heterogeneous catalyst on the electrode's surface.…”

Section: ■ Conversion Of Mn Complexes To Mn Oxidementioning

confidence: 95%

“…The Randles−Sevcik equation has been used to determine the TOF of homogeneous electrocatalysts. 29 In the presence of a metal complex, the dynamical deposition/dissolution of the heterogeneous catalyst during WOR was not clear enough, which made the Randles−Sevcik equation too complicated to calculate the TOF. 29 The classically used postcharacterization methods are not sufficiently accurate to confirm the homogeneity of WOR mechanisms, so using the Randles− Sevcik equation to calculate the TOF is not necessarily correct.…”

Section: ■ Conversion Of Mn Complexes To Mn Oxidementioning

confidence: 99%

“…The Randles–Sevcik equation has been used to determine the TOF of homogeneous electrocatalysts . In the presence of a metal complex, the dynamical deposition/dissolution of the heterogeneous catalyst during WOR was not clear enough, which made the Randles–Sevcik equation too complicated to calculate the TOF .…”

Section: Conversion Of Mn Complexes To Mn Oxidementioning

confidence: 99%

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Candidate for Catalyst during Water-Oxidation Reaction in the Presence of Manganese Compounds, from Nanosized Particles to Impurities: Sleep with One Eye Open

Najafpour

2022

Acc. Chem. Res.

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Metrics & MoreArticle Recommendations CONSPECTUS: Water-oxidation reaction (WOR) catalysts are critical for energy conversion. WOR is a four-electron oxidation and sluggish reaction. WOR needs a high thermodynamic driving force; it is also a kinetically slow reaction. Different compounds have been used for WOR; among these compounds, Mn materials have proven to be interesting because Mn is low-cost and also nontoxic, at least compared to many transition metals. Naturally, it has also been used in the biological water-oxidizing complex (WOC). Indeed, WOR has occurred on a huge scale in natural photosynthesis.For a long time, efforts have been made to design and synthesize various ligands and generate Mn compounds toward WOR catalysts. However, the addition or removal of electrons inside Mn compounds during harsh WOR conditions can lead to the formation or the breakage of bonds and result in the conversion of a precatalyst to a catalyst.Here, our findings on the conversion of Mn compounds to catalysts during WOR are presented. Many Mn compounds have been claimed to be catalysts for WOR in the presence of various chemical oxidants or under electrophotochemical conditions. Currently, the advances in characterization techniques and different spectroscopic methods have enabled a better understanding of catalysts. Different conversions such as that of the Mn complex to Mn oxide and Mn salts to Mn oxide during WOR have been explained. Indeed, the morphology and size of the Mn oxide formed depend on several factors such as the origin compounds, pH, ligands, and conditions. Thus, different Mn compounds show different activities toward WOR. The biomimetic models with Mn−Ca clusters are also decomposed during WOR. On the other hand, stable Mn complexes such as Mn phthalocyanines, which are very stable in the absence of potential, are easily decomposed during WOR. It is noted that for many of these Mn compounds, two steps result in the formation of Mn oxide during WOR: (i) Mn(II) or (III) leaching into the electrolyte and (ii) deposition of the leached Mn ions into the solution.Considering these steps, it can be seen that challenges remain in the area of Mn compounds, given the fact that even in the catalytic cycle at low oxidation numbers no Mn(II) or (III) should be leached to the electrolyte.

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Unraveling the Multifunctional Mechanism of Fluoroethylene Carbonate in Enhancing High‐Performance Room‐Temperature Sodium‐Sulfur Batteries

Weng,

Liu,

et al. 2024

Angewandte Chemie

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Room‐temperature sodium‐sulfur (RT Na‐S) batteries has attracted growing attentions in large‐scale energy storage technology, while the serious shuttle effect and interface side reaction limit its practical application. Despite fluoroethylene carbonate (FEC) has been widely used as an electrolyte additive or co‐solvent to facilitate the optimization of electrode‐electrolyte interphase in RT Na‐S batteries, its crucial influence and mechanism have not been clearly understood. Herein, we deeply reveal the two‐steps cathode‐electrolyte interphase (CEI) formation by using FEC as the exclusive electrolyte solvent. The results demonstrate that FEC participates in both rapid nucleophilic reaction and electrochemical decomposition on cathode, which can effectively in situ construct a unique "chocolate‐cookie" shaped CEI consisted of NaF‐rich double layers. This CEI eliminates the shuttle effect and ensures the solid‐solid conversion of sulfur. Along with the stable F‐rich solid‐electrolyte interphase (SEI) formed on the Na anode, the RT Na‐S battery delivers an impressive performance (456 mAh g‐1 after 1000 cycles at 0.5 C) with almost 100% Coulombic efficiency. This significantly simplifies electrolyte design and provides valuable insights into the application of FEC in practical Na‐S batteries

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The importance of identifying the true catalyst when using Randles-Sevcik equation to calculate turnover frequency

Cited by 44 publications

References 45 publications

Quantification of Tyrosine in Pharmaceuticals with the New Biosensor Based on Laccase-Modified Polypyrrole Polymeric Thin Film

Quantification of Tyrosine in Pharmaceuticals with the New Biosensor Based on Laccase-Modified Polypyrrole Polymeric Thin Film

Candidate for Catalyst during Water-Oxidation Reaction in the Presence of Manganese Compounds, from Nanosized Particles to Impurities: Sleep with One Eye Open

Unraveling the Multifunctional Mechanism of Fluoroethylene Carbonate in Enhancing High‐Performance Room‐Temperature Sodium‐Sulfur Batteries

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