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%)-K 2 TiF 6 melt with addition of Ca 2+ 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 Ca 2+ /Ti(IV) equals 1:1 was found. Values of activation energy for system with Ca 2+ cations are considerably less than activation energies of the system without Ca 2+ 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 TiF 6 2− complex. The calculated activation energy of the electron transfer was in a good agreement with experimentally determined value.