Mathematical modeling of kinetic behavior of the hydrogen electrode in carbonate melts under non-steady-state conditions: An analysis of various reaction schemes

摘要

An extended analysis of the kinetic behavior exhibited by the hydrogen electrode in a molten carbonate electrolyte is performed by a method of mathematical modeling of relaxation processes as applied to chronoamperometric and coulostatic experiments. A set of differential equations with corresponding initial and boundary conditions, which fixes the balance of charge and substance at the electrode/electrolyte interface, is presented for several particular versions of reaction schemes and the method used for bringing the system out of equilibrium. Numerical calculations are performed and their results are compared with the experimental time dependences of the current and overvoltage obtained in chronoamperometric and coulostatic conditions, respectively. As a result, possible intervals of variations in the kinetic, adsorption, and transport parameters of the system are evaluated. The deviations of their values when using different investigation procedures and different electrode materials (gold, nickel) are discussed. To differentiate assorted reaction schemes as applied to a real electrode process of the anodic oxidation of hydrogen in a carbonate electrolyte it is necessary to expand the base of experimental material to be analyzed and the circle of procedures to be used for investigation.