Charge Transfer Rate Constant Research Articles

Electrochemistry of Neodymium in an Equimolar NaCl-KCl Melt without and with Addition of Fluoride Ions

The paper presents results of neodymium electrochemical behavior in chloride and chloride-fluoride melts. It was shown that the process of neodymium electroreduction in the NaCl-KCl-NdCl3 melt proceeds in two stages. It was established by diagnostic criteria of voltammetry that the discharge process of Nd(III) to Nd(II) at a sweep rate in the range of 0.6 ≤ n ≤ 1.0 V s-1 is not complicated by reaction disproportionation. In this study diffusion coefficients, activation energy of diffusion for Nd(III) complexes and standard rate constants of charge transfer for the Nd(III)/Nd(II) redox couple in the NaCl-KCl melt were determined. It was shown that the addition of fluorine anions into the NaCl-KCl-NdCl3 melt leads to stabilization of the higher oxidation state of neodymium in chloride-fluoride melts and neodymium in the intermediate oxidation state +2 in these melts does not exist.

Kinetic and Thermodynamic Properties of Ytterbium Chloride and Fluoride Complexes in Chloride Melts

The electrochemical behavior of ytterbium in NaCl-KCl, KCl and CsCl melts was studied in the temperature range 973-1173 K by different electrochemical methods. The diffusion coefficients (D) of Yb(III) and Yb(II) were determined by linear sweep voltammetry, chronopotentiometry and chronoamperometry methods. The standard rate constants of charge transfer (k s) for the Yb(III)/Yb(II) redox couple were calculated on the basis of cyclic voltammetry data using Nicholson’s equation. The formal redox potentials E* Yb(III)/Yb(II) were obtained in alkali chlorides melts from the cyclic voltammetry data. The influence of fluoride ions on the standard rate constants in the NaCl-KCl melt was investigated.

(Digital Presentation) Charge Transfer Kinetics of the Ti(IV)/Ti(III) Redox Couple in the Cesium Chloride-Cesium Fluoride Melt with Addition of Alkaline Earth Metal Cations

The electrochemical behavior of the Ti(IV)/Ti(III) redox couple in the CsCl-CsF(10 wt.%)-K2TiF6 melt was studied. The standard rate constants of charge transfer for the Ti(IV)/Ti(III) redox couple in CsCl-CsF(10 wt.%)-K2TiF6-based melts with additions of alkaline earth metal cations (Mg2+, Ca2+, Sr2+ and Ba2+) were determined by cyclic voltammetry method. The activation energies of charge transfer process were calculated. The linear dependence of charge transfer rate constants on the ionic potential of alkaline earth metal cations was found.

Modeling the Photostability of Solar Water-Splitting Devices and Stabilization Strategies.

The practical implementation of photoelectrochemical devices for hydrogen generation is limited by their short lifetimes. Understanding the factors affecting the stability of the heterogeneous photoelectrodes is required to formulate degradation mitigation strategies. We developed a multiscale and multiphysics model to investigate and quantify the photostability of photoelectrodes. The model considers the photophysical processes in an electrocatalyst-coated semiconductor immersed in electrolyte, and the kinetics of the competing water-splitting and photocorrosion reactions. When applied to 12 promising compound semiconductors for use as photoanodes (GaAs, GaP, InP, GaN, SiC, AlP, AlAs, CdTe, CdS, CdSe, ZnS, and ZnSe), the semiconductor-electrocatalyst interfacial charge transfer rate constant was found to be the most significant parameter for stabilizing the photoelectrodes. Its increase induced a sigmoid-like increase in photostability, and its optimization made it possible to stabilize nine semiconductors. The semiconductor surface back-bond energy also increased the photostability in a sigmoid-like response, and its optimization allowed to stabilize five semiconductors. The increase of irradiance induced a logarithmic drop in photostability, and limiting it to 100 W/m2 could stabilize three semiconductors. We further observed that the photostability in a device of centimeter-scale can vary by more than 50%, showing stable zones and photocorrosion hotspots. The photoelectrode's length as well as the electrocatalyst and electrolyte conductivities were found to be relevant parameters to impact this heterogeneity in the photostability. Thus, the photostability is not only defined by material properties but also by the specific combination of materials and by the device architecture. The model presented in this study can also be applied to photocathodes and other PEC designs, and can serve as a design tool for understanding, quantifying, and improving the stability.

Nano-porous TiO2 electrochemically doped with Mo oxide – Composition, electrochemical and photo-electrochemical properties

Mixed Mo–Ti oxides are synthesized in nano-porous TiO2 templates by electrochemical deposition using cyclic voltammetry and stabilized by thermal treatment. Their thickness, phase, elemental, and chemical composition are characterized using X-ray diffraction, X-ray photoelectron spectroscopy and Glow discharge optical emission spectroscopy. Films are found to contain up to 17%Mo, mainly as Mo(VI) with some amounts of Mo(V). Electrical and electrochemical properties are assessed by current-potential measurements and electrochemical impedance spectroscopy. Photocurrent energy spectra and intensity modulated photocurrent spectroscopy (IMPS) measurements indicate that the films absorb UV and visible light in the range 365–520 nm and exhibit photo-catalytic properties. Quantitative interpretation of IMPS data using a transfer function proposed in the literature yields rate constants of charge transfer and recombination. The dependences of the kinetic parameters on potential are correlated with a mechanistic model of oxygen evolution featuring a mobile intermediate.

An Accurate Linearized Semiclassical Approach for Calculating Cavity-Modified Charge Transfer Rate Constants.

We show that combining the linearized semiclasscial approximation with Fermi's golden rule (FGR) rate theory gives rise to a general-purpose cost-effective and scalable computational framework that can accurately capture the cavity-induced rate enhancement of charge transfer reactions that occurs when the molecular system is placed inside a microcavity. Both partial linearization with respect to the nuclear and photonic degrees of freedom and full linerization with respect to nuclear, photonic, and electronic degrees of freedom (the latter within the mapping Hamiltonian approach) are shown to be highly accurate, provided that the Wigner transforms of the product (WoP) of operators at the initial time is not replaced by the product of their Wigner transforms. We also show that the partial linearization method yields the quantum-mechanically exact cavity-modified FGR rate constant for a model system in which the donor and acceptor potential energy surfaces are harmonic and identical except for a shift in the equilibrium energy and geometry, if WoP is applied.

Cobalt Oxide Nanorod-Modified GCE as Sensitive Electrodes for Simultaneous Detection of Hydroquinone and Catechol

An electrochemical sensor based on a cobalt oxide nanorod (Co3O4NR) modified glassy carbon electrode (GCE) (Co3O4NR-GCE) was prepared for simultaneous and selective determination of hydroquinone (HQ) and catechol (CT). Surface morphology and crystallinity of Co3O4NR were investigated employing field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD) analysis. The structure (16 nm) of the Co3O4 nanorod was observed in the FESEM image. A sharp peak pattern in the XRD survey revealed the following crystal planes in Co3O4NR material: (111), (220), (311), (222), (400), (422), (511), and (440). Electrochemical characterization of modified Co3O4NR-GCE was carried out performing cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Selective and simultaneous detection of HQ and CT was carried out by performing CV and differential pulse voltammetry (DPV) analysis. In both studies, modified Co3O4NR-GCE showed well defined oxidation and reduction peaks for HQ and CT with enhanced peak current, and the oxidation peaks for HQ and CT were observed at 0.152 V and 0.254 V, respectively, in the CV analysis. Scan rate and pH variation analysis were performed to evaluate different kinetic parameters, including charge transfer coefficient (α = 0.56 for HQ and 0.66 for CT), heterogeneous charge transfer rate constant (ks = 56 for HQ and 72 for CT), and the number of electrons involved in HQ and CT oxidation. Quantitative analysis of HQ and CT was studied by observing the current response of DPV analysis with respect to concentration variation. Here, the detection limit was calculated as 0.2 µM for HQ with a linear concentration range of 5–200 µM, and 0.4 µM for CT with a linear concentration range of 5–150 µM. The practical applicability of the proposed sensor was investigated using sample solutions prepared in tap water. The reported sensor showed impressive selectivity towards HQ and CT in the presence of common interferents.

Quadrupolar Ultrafast Charge Transfer in Diaminoazobenzene-Bridged Perylenediimide Triads.

Strong push-pull interactions between electron donor, diaminoazobenzene (azo), and an electron acceptor, perylenediimide (PDI), entities in the newly synthesized A-D-A type triads (A=electron acceptor and D=electron donor) and the corresponding A-D dyads are shown to reveal wide-band absorption covering the entire visible spectrum. Electrochemical studies revealed the facile reduction of PDI and relatively easier oxidation of diaminoazobenzene in the dyads and triads. Charge transfer reversal using fluorescence-spectroelectrochemistry wherein the PDI fluorescence recovery upon one-electron oxidation, deterring the charge-transfer interactions, was possible to accomplish. The charge transfer state density difference and the frontier orbitals from the DFT calculations established the electron-deficient PDI to be an electron acceptor and diaminoazobenzene to be an electron donor resulting in energetically closely positioned PDIδ- -Azoδ+ -PDIδ- quadrupolar charge-transfer states in the case of triads and Azoδ+ -PDIδ- dipolar charge-transfer states in the case of dyads. Subsequent femtosecond transient absorption spectral studies unequivocally proved the occurrence of excited-state charge transfer in these dyads and triads in benzonitrile wherein the calculated forward charge transfer rate constants, kf , were limited to instrument response factor, meaning >1012 s-1 revealing the occurrence of ultrafast photo-events. The charge recombination rate constant, kr , was found to depend on the type of donor-acceptor conjugates, that is, it was possible to establish faster kr in the case of triads (∼1011 s-1 ) compared to dyads (∼1010 s-1 ). Modulating both ground and excited-state properties of PDI with the help of strong quadrupolar and dipolar charge transfer and witnessing ultrafast charge transfer events in the studied triads and dyads is borne out from the present study.

Influence of donor-to-acceptor ratio on excited-state electron transfer within covalently tethered CdSe/CdTe quantum dot colloidal heterostructures.

Carbodiimide-mediated coupling chemistry was used to synthesize heterostructures of CdSe and CdTe quantum dots (QDs) with varying ratios of electron-donating CdTe QDs and electron-accepting CdSe QDs. Heterostructures were assembled via the formation of amide bonds between the terminal functional groups of CdTe-adsorbed 4-aminothiophenol (4-ATP) ligands and CdSe-adsorbed N-hydroxysuccinimide (NHS) ligands. The number of charge acceptors on the surfaces of QDs can greatly influence the rate constant of excited-state charge transfer with QDs capable of accommodating far more acceptors than molecular chromophores. We report here on excited-state electron transfer within heterostructure-forming mixtures of 4-ATP-capped CdTe and NHS-capped CdSe QDs with varying molar ratios of CdTe to CdSe. Photophysical properties and charge transfer were characterized using UV-vis absorption, steady-state emission, and time-resolved emission spectroscopy. As the relative concentration of electron-accepting CdSe QDs within mixtures of 4-ATP-capped CdTe and NHS-capped CdSe QDs increased, the rate and efficiency of electron transfer increased by 100-fold and 7.4-fold, respectively, as evidenced by dynamic quenching of band-edge emission from CdTe QDs. In contrast, for non-interacting mixtures of thiophenol capped CdTe QDs and NHS-capped CdSe QDs, which served as control samples, photophysical properties of the constituent QDs were unperturbed and excited-state charge transfer between the QDs was negligible. Our results reveal that carbodiimide-mediated coupling chemistry can be used to control the relative number of donor and acceptor QDs within heterostructures, which, in turn, enables fine-tuning of charge-transfer dynamics and yields. These amide-bridged dual-QD heterostructures are, thus, intriguing for light harvesting, charge transfer, and photocatalysis.

A Novel Label‐free Chronoamperometric Immunosensor Based on a Biocomposite Material for Rapid Detection of Carcinoembryonic Antigen

AbstractIn this research, poly(diallyldimethylammonium chloride)‐capped gold nanoparticles, nickel ferrite particles, and carbon nanotubes were combined to form a PANC metal composite. The prepared metal composite modified onto a glassy carbon electrode was electropolymerized with poly(o‐phenylenediamine) and immobilized with horseradish peroxidase, anti‐carcinoembryonic antigen antibody, and bovine serum albumin to create the label‐free immunosensors for rapid detection of carcinoembryonic antigen (CEA) using chronoamperometry. This developed biocomposite material modified onto a glassy carbon electrode presented an excellent electrocatalytic response to the redox reaction of hydrogen peroxide as a sensing probe, from which the kinetic parameters including of a charge transfer rate constant, a diffusion coefficient value, an electroactive surface area, and a surface concentration were calculated to be 1.85 s−1, 4.28×10−6 cm2 s−1, 0.14 cm2 and 1.87×10−8 mol cm−2, respectively. The developed immunosensors also exhibited a wide linear range of CEA concentration from 0.01 to 25 ng mL−1 with high sensitivity (96.21 μA cm−2 ng−1 mL) and low detection limit (0.72 pg mL−1), excellent selectivity without interfering effects from possible species (amoxicillin, ascorbic acid, aspirin, caffeine, cholesterol, dopamine, glucose, and uric acid), outstanding stability (n=100, %I>50 %), repeatability (%RSD=0.34, n=10), reproducibility (%RSD=4.06, n=10), and rapid analysis (25 s each operation time). This proposed method was successfully applied for CEA detection in whole blood samples with satisfactory results, suggesting that this developed sensing platform may be considered to be exploited for fabrication of other label‐free electrochemical immunosensors for the real sample analysis.

Improvement the energy conversion efficiency of organic dye-based solar cells by pioneer solvents

In this report, a physicochemical study was performed on a series of organic dyes (AE, AQ, TE, and TQ) in the gas phase and solvent through the molecular approach. Triphenylamine/dimethylaniline as electron donors and 1,1,4,4-tetracyanobuta-1,3-dienes (derived from TCNE)/ 2-(4-(4,4-dicyanobut-3-en-2-ylidene)cyclohexa-2,5-dien-1-ylidene)malononitrile (derived from TCNQ) as the electron acceptors were utilised in this system. The introduction of strong electron acceptors of TCNE and TCNQ elevates electron transfer processes and makes the suggested dyes favourable to be used in the dye-sensitized solar cell (DSSC). On the basis of the obtained results, TCNQ-adduct dyes (AQ and TQ) have the highest charge transfer distance, excited-state lifetime, and the lowest overlap of the electron–hole distribution in comparison with TCNE-adduct dyes (AE and TE). The analysis of the charge transfer indices shows the amplification effect of the solvents in comparison with the gas phase and DMF as the solvent represents the best performance. Also, the maximum electron transfer rate constant and minimum electronic chemical hardness belong to the TCNQ-adduct dyes. Finally, AQ and TQ as the dyes and DMF as the solvent are introduced as the most promising candidates to be applied in the DSSCs due to efficient charge transfer and electron transfer rate constant.

Preparation and electrochemical characterization of TiO2 as an anode material for magnesium-ion batteries

Anode on the basis of titanium dioxide powder was made. Its morphological characteristics were investigated using ellipsometry, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD). Electrochemical properties were also investigated by cyclic voltammetry. Dispersing, mixing the initial reagents for obtaining homogenized paste and its coating to a substrate, drying and cutting the electrodes were main steps of anode production. The results of ellipsometry, SEM and EDS demonstrated a uniformly distributed layer of about 200 μm thickness with porous structure, particle diameter of 50–80 nm and titanium dioxide content (45.7 %). The XRD data confirmed the active anode matrix formation with a monoclinic crystal lattice corresponding to the modification of titanium dioxide (B) with small anatase inclusions. Electrochemical behavior of the electrode was examined in acetonitrile-based Mg(TFSI)2 solution. Diffusion coefficient (DMg) and the charge transfer rate constant (kct) were determined from cyclic voltammograms 1.54∙10–2 cm2/s and 1.29∙10–4 cm/s, respectively. A two-step electrochemical reaction was revealed by the ratio of the electricity amount consumed in the cathode and anode processes at varying the number of cycles. Small values of polarization resistance (Rp) calculated from cyclic voltammograms indicated rapid diffusion of magnesium ions during intercalation/deintercalation.

The Halogenation Effects of Electron Acceptor ITIC for Organic Photovoltaic Nano-Heterojunctions.

Molecular engineering plays a critical role in the development of electron donor and acceptor materials for improving power conversion efficiency (PCE) of organic photovoltaics (OPVs). The halogenated acceptor materials in OPVs have shown high PCE. Here, to investigate the halogenation mechanism and the effects on OPV performances, based on the density functional theory calculations with the optimally tuned screened range-separated hybrid functional and the consideration of solid polarization effects, we addressed the halogenation effects of acceptor ITIC, which were modeled by bis-substituted ITIC with halogen and coded as IT-2X (X = F, Cl, Br), and PBDB-T:ITIC, PBDB-T:IT-2X (X = F, Cl, Br) complexes on their geometries, electronic structures, excitations, electrostatic potentials, and the rate constants of charge transfer, exciton dissociation (ED), and charge recombination processes at the heterojunction interface. The results indicated that halogenation of ITIC slightly affects molecular geometric structures, energy levels, optical absorption spectra, exciton binding energies, and excitation properties. However, the halogenation of ITIC significantly enlarges the electrostatic potential difference between the electron acceptor and donor PBDB-T with the order from fluorination and chlorination to bromination. The halogenation also increases the transferred charges of CT states for the complexes. Meanwhile, the halogenation effects on CT energies and electron process rates depend on different haloid elements. No matter which kinds of haloid elements were introduced in the halogenation of acceptors, the ED is always efficient in these OPV devices. This work provides an understanding of the halogenation mechanism, and is also conducive to the designing of novel materials with the aid of the halogenation strategy.

Стандартные константы скорости переноса заряда редокс-пары Ti(IV)/Ti(III) в хлоридно-фторидных расплавах с различным катионным составом

The influence of the second coordination sphere of titanium complexes on the charge transfer kinetics of the Ti (IV)/Ti (III) redox couple in melts of alkali metal halides was studied by cyclic voltammetry method. Diffusion coefficients in the CsC-CsF (10 wt. %) melt were calculated. The standard rate constants of charge transfer have been determined by the Nicholson method. The activation energies of the charge transfer process in (NaCl- KCl)equimol-NaF (10 wt. %) — K2TiF6, KCl-KF (10 wt. %) — K2TiF6 and CsCl-CsF (10 wt. %) — K2TiF6 melts were calculated.

Solar-to-Pharmaceutical Raw Material Production: Photoelectrochemical Naphthoquinone Formation Using Stabilized BiVO4 Photoanodes in Acid Media.

In the quest for efficient use of solar energy to produce high-value-added chemicals, we first achieved the photoelectrochemical (PEC) diketonization of naphthalene, using a BiVO4/WO3 photoanode, to obtain naphthoquinone, an important pharmaceutical raw material with excellent efficiency by solar energy conversion. In the electrochemical (EC) reaction using F-doped SnO2 (FTO) substrates and a 0.5 M H2SO4 H2O-acetone (60 vol %) mixed solution containing 5 mM naphthalene, we produced a small amount of naphthoquinone evolution in the dark. However, naphthoquinone (ηNQ)'s Faradic efficiency and its evolution rate at 1.7 VAg/AgCl were only 28.5% and 0.48 μmol·cm-2·h-1, respectively. The PEC reaction using a WO3 photoanode had very low efficiency for naphthalene diketonization, with low ηNQ and evolution rate values at 1.1 VAg/AgCl of 0.3% and 0.039 μmol·cm-2·h-1, respectively. In contrast, the BiVO4/WO3 photoanode strongly enhanced the PEC reaction, and the ηNQ and evolution rates at 1.1 VAg/AgCl were boosted up to 37.5% and 4.7 μmol·cm-2·h-1, respectively. The evolution rate of the PEC reaction in the BiVO4/WO3 photoanode was 10 times higher than that of the EC reaction with the FTO substrate regardless of the very low bias voltage. This result suggests that the BiVO4-based photoanode was very efficient for the selective oxidation of naphthalene even in acid media because of the acetone-mixed electrolyte's anti-photocorrosion effect and the multilayering of WO3 and BiVO4. At a naphthalene concentration of 20 mM, the naphthoquinone evolution rate reached its maximum value of 7.1 μmol·cm-2·h-1. Although ηNQ tended to decrease with the increase in the electric charge, it reached 100% at a low bias voltage of 0.7 VAg/AgCl. An intensity-modulated photocurrent spectroscopy analysis indicated the rate constant of charge transfer at the photoanode surface to the naphthalene molecules was strongly enhanced at a low bias voltage of 0.7-1.1 VAg/AgCl, resulting in the high ηNQ value. The acid-resistant BiVO4/WO3 photoanode functioned in acetone-mixed electrolytes enabled the realization of a new PEC oxidation reaction driven by solar energy to produce high-value-added pharmaceutical raw materials.

Beyond the Laviron Method: A New Mathematical Treatment for Analyzing the Faradaic Current in Reversible, Quasi-Reversible, and Irreversible Cyclic Voltammetry of Adsorbed Redox Species.

A new algorithm that describes the faradaic current for elementary redox reactions in the cyclic voltammetric responses of persistently adsorbed species on metal electrodes at any scan rate is presented. This work does not assume electrochemical reversibility and instead demonstrates a set of equations that encapsulate how the forward and back charge-transfer rate constants influence the data as a function of the experimental time scale. The method presented here is compared against other approaches that rely on either finite-difference calculations or that require numerical approximation of improper integrals (i.e., ±infinity as a bound). The method here demonstrates that the current-potential data can be described by incomplete gamma functions, whose two arguments capture the relevant kinetic variables. Following the notation for the Butler-Volmer model of charge transfer, exact solutions are presented for the cases of the charge-transfer coefficient, α, equal to 1 or 0. A related algorithm based on these results affords calculation of current-potential data for 0 < α < 1, allowing comprehensive analysis (i.e., point by point) of voltammetric data throughout the reversible, quasi-reversible, and irreversible regimes. Accordingly, this work represents an alternative to the method of Laviron, i.e., analyzing just the peak splitting values, for experimentalists to understand and interpret their voltammetric data in totality.

Insights on interfacial charge transfer across MoS2/TiO2-NTAs nanoheterostructures for enhanced photodegradation and biosensing&gas-sensing performance

Novel MoS2 nanobelts (NBs) decorated highly ordered alignment TiO2 nanotubes arrays (TiO2-NTAs) with promoted photoelectrocatalytic (PEC) photodegradation and sensing performance under UV-Visible light irradiation were successfully synthesized via a facile combination of anodization and electrodeposition procedure. Simultaneously, the MoS2/TiO2-NTAs nanohybrids presented a significantly enhanced for PEC activity tests, which were mainly ascribed to the synergistic effect between MoS2 NBs and TiO2-NTAs for the efficient separation of photogenerated carriers induced by the enlarged staggered band offset associated with sulfur vacancies defects. Furthermore, self-consistent interfacial charge transfer mechanism and convincing quantitative dynamic process (i.e. rate constant of charge transfer) for MoS2/TiO2-NTAs type-II nanoheterojunctions mediated with the p-type doping effect are proposed, which were evaluated by nanosecond time-resolved transient photoluminescence (NTRT-PL) and time-resolved photoluminescence (TRPL) spectra, respectively. Following this scheme, the photodegradation rate (η) toward degradation of methyl orange for optimum MoS2/TiO2-NTAs-2 nanocomplex was 96% irradiated by UV-Visible light, which are 1.2 and 1.1 times than that of MoS2/TiO2-NTAs-1 and MoS2/TiO2-NTAs-5, respectively. Furthermore, the PEC biosensing analysis of MoS2/TiO2-NTAs-2 was performed for detecting the glutathione, leading to an excellent detect limit of 1.6 μM and the sensitivity of 930 mA cm-2 M-1. Additionally, the sensitivity of gas-sensing for MoS2/TiO2-NTAs-2 is 3.1, which are 1.3 and 1.1 folds than that of MoS2/TiO2-NTAs with MoS2 deposited times 1 min and 5 min, respectively. It is distinctly manifested that the gas sensing performance of MoS2/TiO2-NTAs-2 toward ammonia gas is superior than that of MoS2/TiO2-NTAs-1 and MoS2/TiO2-NTAs-5 in terms of higher sensitivity degree and faster response speed.

CTRAMER: An open-source software package for correlating interfacial charge transfer rate constants with donor/acceptor geometries in organic photovoltaic materials.

In this paper, we present CTRAMER (Charge-Transfer RAtes from Molecular dynamics, Electronic structure, and Rate theory)-an open-source software package for calculating interfacial charge-transfer (CT) rate constants in organic photovoltaic (OPV) materials based on ab initio calculations and molecular dynamics simulations. The software is based on identifying representative donor/acceptor geometries within interfacial structures obtained from molecular dynamics simulation of donor/acceptor blends and calculating the corresponding Fermi's golden rule CT rate constants within the framework of the linearized-semiclassical approximation. While the methods used are well established, the integration of these state-of-the-art tools originating from different disciplines to study photoinduced CT processes with explicit treatment of the environment, in our opinion, makes this package unique and innovative. The software also provides tools for investigating other observables of interest. After outlining the features and implementation details, the usage and performance of the software are demonstrated with results from an example OPV system.

Electrochemical Behavior of SmF3 in Alkali Chloride Melts

Electrochemical studies of the Sm(III)/Sm(II) redox couple were carried out in NaCl-KCl, KCl and CsCl melts in a temperature range of 973–1173 K by cyclic voltammetry. Diffusion coefficients (D) of Sm(III) in these melts were determined using the Randles–Sevchik equation. Diffusion coefficients decrease with a change in the composition of the second coordination sphere from sodium to cesium. It is associated with a decrease in the counter-polarizing effect during the transition from Na to Cs, which in turn causes a decrease the metal—ligand bond length in the complexes. The standard rate constants of charge transfer (k s) of the Sm(III)/Sm(II) redox couple were determined by cyclic voltammetry in all studied melts using the Nicholson’s equation, which is valid for quasi-reversible processes. The following series of the standard rate constants of charge transfer was found k s(CsCl) < k s(KCl) < k s(NaCl–KCl).

Study of the Electron Transfer in Titanium Containing Melts by Electrochemical and Quantum-Chemical Methods

The electron transfer mechanism in a titanium containing system was investigated by electrochemical and quantum-chemical methods. The kinetics of charge transfer for the Ti(IV)/Ti(III) redox couple in the (NaCl–KCl)equimol–NaF (10 wt%)-K2TiF6 melt with addition of Ca2+ cations was studied by cyclic voltammetry. The standard rate constants of charge transfer (k s ) were calculated by Nicholson’s method. The increase values of the k s reaching the maximum at mole ratio Ca2+/Ti(IV) equals 1:1 was found. Values of activation energy for system with Ca2+ cations are considerably less than activation energies of the system without Ca2+ cations. The quantum-chemical calculations were performed using the Firefly quantum-chemical package by methods of the density functional theory. Structures with a high probability of the electron transfer from the cathode to the titanium complex were found. Using the Frontier molecular orbital method made it possible with a small amount of computer time to determine the structure of the transition state of the TiF6 2− complex. The calculated activation energy of the electron transfer was in a good agreement with experimentally determined value.