Effect of the ionic strength on the redox reaction of dicyanobis(bipyridine)iron(III)‐iodide in binary and ternary solvent systems

Khattak, Rozina; Khan, Muhammad Sufaid; Zainab,; Sony,; Ali, Mahnoor; Rahman, Wajeeha; Hakeem, Faryal; Ayaz, Kainat; Bibi, Zainab

doi:10.1002/kin.21419

Cited by 7 publications

(6 citation statements)

References 17 publications

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“…The molar absorptivity of the reduced ferricyphen i.e., ferrocyphen, and reduced ferricypyr i.e., ferrocypyr are several folds higher than the oxidized ferrocyphen (ferricyphen) and ferrocypyr (ferricypyr). The spectra of the reactants and products are shown in Figure 2B and compared to the literature [21][22][23][24][25][26][27][28][29] that supports the electron transfer mechanism. The integration method was implemented to figure out the rate constant.…”

Section: Methodology and Kinetics Studiessupporting

confidence: 66%

“…The reduction potential of ferrocyanide is comparable to the iodide electrolyte, hence displays its replacement over iodide. The oxidation of iodide by ferricyphen and ferricypyr has been studied in acetonitrile, aqueous tertiary butyl alcohol, and aqueous 1,4-dioxane [23][24][25][26]. The comparative kinetic analysis shows the rapid kinetics of ferricyphen over ferricypyr in binary solvent media under optimized experimental conditions.…”

Section: Introductionmentioning

confidence: 99%

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Catalytic Behavior of Extended π-Conjugation in the Kinetics of Sensitizer-Mediator Interaction

Khattak¹

2022

Recent Advances in Chemical Kinetics

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This chapter discusses the catalytic effect of extended π-conjugation on the electron transfer process between ferricyphen-ferrocyanide and ferricypyr-ferrocyanide in an aqueous medium. Ferricyphen and ferricypyr may be feasible options for the sensitizer in dye-sensitized solar cells due to their high reduction potential, stability, capability as an outer-sphere oxidant, and photosensitivity. Meanwhile, ferrocyanide could be used as a mediator in DSSCs instead of iodide to avoid iodate production and achieve a similar reduction potential and stability. This chapter compared the ability of competent putative sensitizers to oxidize the likely mediator in water. In contrast to the 2,2′-dipyridyl chelate, the extended π-conjugation in 1,10-phenanthroline accelerated the redox process by increasing the electron affinity of ferricyphen as compared to ferricypyr. The reactions had the same kinetics but different rate constants, indicating that the ferricyphen-ferrocyanide reaction was several times faster than the ferricypyr-ferrocyanide reaction, revealing and confirming the catalytic influence of extended π-conjugation on the redox process.

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Section: Methodology and Kinetics Studiessupporting

confidence: 66%

Section: Introductionmentioning

confidence: 99%

Catalytic Behavior of Extended π-Conjugation in the Kinetics of Sensitizer-Mediator Interaction

Khattak¹

2022

Recent Advances in Chemical Kinetics

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“…The production of new dyes and electron mediators, as well as a better understanding of their interactions and the interfacial electron transfer kinetics is critical for future advancement in this field and is currently the focus of the DSSCs community's scientific efforts [6][7][8]10,[28][29][30][31][32][33][34][35][36]. In terms of kinetics, efficient cell performance is attained when electron transfer events happen quickly.…”

Section: Introductionmentioning

confidence: 99%

Catalytic Effect of 1,4-Dioxane on the Kinetics of the Oxidation of Iodide by Dicyanobis(bipyridine)iron(III) in Water

et al. 2021

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Dye-sensitized solar cells (DSSCs) are a technically and financially viable alternative to today’s photovoltaic systems using p-n junctions. The two functions are isolated here, which are unlike traditional systems where the semiconductor is thought to perform both light absorption and charge carrier transport. This article discusses the potential use of dicyanobis(bipyridine)iron(III) to oxidize iodide as a sensitizer in DSSCs. However, it is critical to understand the kinetics of this essential process in order to understand the mechanism of electron transport. The oxidation of iodide by dicyanobis(bipyridine)iron(III) in three reaction media was studied: water, 10% v/v 1,4-dioxane-water, and 20% v/v 1,4-dioxane-water. The reaction was carried out in a regular laboratory setting, with no special sensitive conditions or the use of expensive materials, making it a cost-effective and practical method. Dicyanobis(bipyridine)iron(III) oxidized iodide in selected media at 0.06 M ionic strength and constant temperature. The reaction was subjected to a spectrophotometric analysis. The data were acquired by measuring the rise in visible absorbance as a function of time after the formation of dicyanobis(bipyridine)iron(II). The reaction proceeded with an overall fractional (0.5), first order, and third order in water, 10% media, and 20% media, respectively. The presence of dicyanobis(bipyridine)iron(III) in either of the reaction media had no effect on the rate. The effect of protons (H+) on the rate constant indicated resistance in water and catalysis in dioxane-water media containing 10–20% dioxane. When the ionic strength was raised, there was no change in the rate constant in water, but there was a deceleration in both binary solvent media. In an aqueous medium, the thermodynamic parameters of activation were computed as Ea 46.23 kJ mol−1, 24.62 M s−1, ΔH# 43.76 kJ mol−1, ΔS# −226.5 J mol−1 K−1, and ΔG# 111.26 kJ mol−1 (25 °C). By increasing the rate of the reaction to its maximum, this study discovered the binary solvent media with the highest catalytic efficiency, i.e., 20% v/v 1,4-dioxane-water, which may increase the efficiency of DSSCs without using any expensive material or unusual experimental conditions.

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“…When the reaction mechanism is known in all of the selected media, it becomes much easier to exploit this sensitizer-mediator interaction to get the most out of the reaction in a DSSC where the rate of the reaction is solely dependent on the mediator. The zero order rate constant obtained for each reaction in all reaction media was displayed as a function of the iodide ion concentration (Figure 3) for this experiment [4,35,36]. The redox reaction between dicyanobis(2,2′-dipyridyl)iron(III)-iodide in either 10% TBA-water (bpy-TBA in Figure 3) or 10% dioxane-water (bpy-dioxane in Figure 3) underwent a first order with the zero order rate constant increasing linearly with increasing iodide concentration, yielding a straight line passing through the origin.…”

Section: Kinetics and Solvent Catalysismentioning

confidence: 99%

“…Other reaction parameters, such as the effect of ionic strength in a specific reaction, must be zero or close to zero in order to investigate the effect of the dielectric constant on the rate constant and, as a result, the rate of the reaction. Variation in ionic strength has a significant effect on the rate constant of any reaction, and we can find a theoretical value of the rate constant at zero ionic strength by extrapolating the graph to zero ionic strength, i.e., the intercept of the plot [4], using the transition state theory to formulate the primary salt effect. The theoretical value of the rate constant at zero ionic strength is known as the ideal value of the rate constant.…”

Section: Introductionmentioning

confidence: 99%

Solvent Catalysis in the Sensitizer-Mediator Redox Kinetics

Khattak¹

2022

Recent Advances in Chemical Kinetics

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The sensitizer-mediator redox reaction is a vital component of the dye-sensitized solar cells (DSSCs). The efficiency and stability of dye-sensitized solar cells are aided by the kinetics of this redox process. Several reaction parameters influence the kinetics of a reaction, and if those parameters are controlled, the rate of the process and its results can be controlled. One of the most important aspects of the sensitizer-mediator interaction is the reaction medium. Aqueous DSSCs are unquestionably a good replacement when it comes to taking a green approach to avoiding toxic, flammable, and volatile organic solvents and their mixtures, which are commonly used in DSSCs and are known to harm the environment while also reducing the lifetime and stability of the DSSCs. The catalytic role of a small volume fraction of organic solvent in the aqueous electron transfer kinetics of a few putative sensitizer-mediator reactions is discussed in this chapter. In binary solvent media including dilute tertiary butyl alcohol (TBA)-water and dilute 1,4-dioxane-water, the reduction of dicyanobis(2,2′-dipyridyl)iron(III) and dicyanobis(1,10-phenanthroline)iron(III) was investigated. The reactions were carried out in a 10% TBA or dioxane to water media with a volume-volume fraction of both solvents using iodide as a reducing agent. The effect of several parameters on the rate constant was also calculated and analyzed.

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Effect of the ionic strength on the redox reaction of dicyanobis(bipyridine)iron(III)‐iodide in binary and ternary solvent systems

Cited by 7 publications

References 17 publications

Catalytic Behavior of Extended π-Conjugation in the Kinetics of Sensitizer-Mediator Interaction

Catalytic Behavior of Extended π-Conjugation in the Kinetics of Sensitizer-Mediator Interaction

Catalytic Effect of 1,4-Dioxane on the Kinetics of the Oxidation of Iodide by Dicyanobis(bipyridine)iron(III) in Water

Solvent Catalysis in the Sensitizer-Mediator Redox Kinetics

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