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.

One-step route for Z-scheme Al2(WO4)3/Bi2WO6 heterojunction toward superior photoelectric and photocatalytic performance

Herein, Al2(WO[Formula: see text]/Bi2WO6 heterojunctions with [Formula: see text]-type structure were successfully prepared by a one-step hydrothermal method. Moreover, the effects of different composite ratios on the properties of materials were explored. The electrochemical tests and photocatalytic degradation experiments showed that the corresponding Al2(WO[Formula: see text]/Bi2WO6 heterojunctions all exhibited improved electrochemical performance and photocatalytic performance than that of the bare Bi2WO6 material. Especially, when the molar ratio of Al to Bi was 2:1, the obtained Al2(WO[Formula: see text]/Bi2WO6 heterojunction displayed the optimal photoelectric and photocatalytic performance. In detail, it depicted the highest photocurrent density, the smallest resistance and the fastest charge transfer rate. What’s more, the RhB solution (10 ppm) could be completely degraded in 30 min under visible-light irradiation, and the removal rate was almost 1.6 times than that of pure Bi2WO6 nanosheets. In the same condition, it also exhibited excellent photocatalytic performance for the degradation of tetracycline (TC) solution (10 ppm) and the K2Cr2O7 solution (40 ppm). These results fully manifested that the constructed Al2(WO[Formula: see text]/Bi2WO6 heterojunction possessed superior photoelectric conversion capacity and outstanding photocatalytic performance. Moreover, based on the obtained experimental results, a [Formula: see text]-scheme mechanism of catalytic degradation of RhB and TC under simulated solar light was proposed and discussed.

Theory of Charge Transfer Reaction Process at the Sensitizers Molecule Dye N3 Contact with MgO Semiconductor

A theoretical charge transport rate approach has taken to study the charge transfer properties in non-homogeneous N3-MgO systems. It develops at the fully quantum transition theory by means of transition energy, potential, driving energy and coupling constant. It is obtained that transition energy is determined by the donor acceptor scenario, dependent on the radii of N3 and MgO, dielectric constant and refractive index of solvents. The transition energy of charge carriers increased with increased dielectric constant and decreased refractive index of solvents. Transition energy of N3-MgO system reach to top with methanol (0.582 ev) and has minimum with Chlorobenzene (0.104eV). Dependences of the driving energy versus chemical potential of N3 dye and conduction band of semiconductor with potential barrier, the charge transfer rate are increased with decreased driving force of system. It is established that increased coupling constant factor reduces to increased charge transfer rate.

Solvent effects on the electronic and optical properties of Ni(II), Zn(II), and Fe(II) complexes of a Schiff base derived from 5-bromo-2-hydroxybenzaldehyde

In this article, the electronic, optical, and charge transfer properties of a Schiff base ligand prepared using 5-bromo-2-hydroxybenzaldehyde and ethyl 6-acetyl-2-amino-4,5,6,7-tetrahydrothieno[2,3- c]pyridine-3-carboxylate (C19H19BrN2O4S) and its Fe(II) (C19H30BrN2O10SClFe), Ni(II) (C19H28BrN2O9SClNi), and Zn(II) (C19H28BrN2O9SClZn) complexes are described based on different solvents environments and supported by theoretical calculations. Theoretical calculations are carried out using density functional theory (DFT/UB3LYP/LANL2DZ). The optical densities, optical band gaps, and refractive indices of the ligand and its Fe(II), Ni(II), and Zn(II) complexes in different solvent environments are obtained. The reorganization energies are calculated to determine the charge transfer rate of the studied compounds using both experimental and theoretical data. These experimental and theoretical results show that the ligand and its metal complexes can be used for optoelectronic applications and charge transfer materials in organic light-emitting diode applications.

Electrochemical studies of 1-ferrocenylmethyl-3-methyl-imidazolium iodide and 1-(ferrocenylmethyl)-3-mesityl-imidazolium iodide: redox potential and substituent effects

The electrochemical behavior of 1-ferrocenylmethyl-3-(methyl)-imidazolium iodide (or mesityl) imidazolium was studied by cyclic voltammetry at glassy carbon electrode in midiums organic to determine the influences of electronic imidazolium group on the ferrocene. The experimental results indicated that the redox reaction was reversible. Mass transport towards the electrode is a simple diffusion process and the diffusion coefficient (D) for redox couple has been also calculated and we have evaluated the heterogeneous charge transfer rate constant (K0). KEY WORDS: Electrochemical behaviour, Cyclic voltammetry, Imidazolium salts, Diffusion coefficient Bull. Chem. Soc. Ethiop. 2020, 34(3), 605-612. DOI: https://dx.doi.org/10.4314/bcse.v34i3.15

Construction of C/MoS2 nanocomposite for highly efficient electrocatalytic NRR

Electrochemical N2 reduction reaction (NRR) has been considered as a promising and green process to replace conventional Haber−Bosch process. However, the presence of sluggish reaction kinetics and competitive hydrogen evolution reaction (HER) can result in poor activity and unsatisfactory selectivity. Here, we proposed C/MoS2 catalysts by a facile ‘one-pot’ hydrothermal method. Benefiting from porous nanosphere structure, it shows outstanding charge transfer rate, which accelerates NRR kinetics. As a result, C/MoS2 exhibited a conspicuously improved NRR performance with a high Faradaic efficiency (FE) of 8.2% at −0.7 V. In addition, this electrocatalyst showed marvelous stability.