Computer Simulation Of Characteristic Of Electrical Double Layer And Diffusion In Electrode Process

The process of electrolysis is complex, it can be affected by many factors, such as properties of electrode, ion size, the concentration of each of the ions and adsorption of special ion. We can know neither the movement of ions in electrolyte or the electrons in electrode clearly, nor their location and state at some special time. Computer simulation, especially for Monte Carlo simulation is a stochastic approach, and its most important characteristic is that it can easily give different probability models to different problem with several different random distributions. In fact it is a technique of randomicity. This method is meanful to the control of electrolysis process. The properties of electrolyte system are studied in this paper with computer simulation method.Firstly, Monte Carlo simulation is applied to the electrical double layer of electrolyzing sodium metaborate, using a discrete surface charge and the restricted primitive model for the electrolyte with minimum image method and long rangecorrections. A systematic examination of the effects of ion size, concentration and mobility and comparison with modified Gouy-Chapman theory(MGC) show that the ion distribution agrees well with MGC theory, and the energy of the system follows Boltzmann distribution.Secondly, this paper regards the electrolyte as three-dimensional gridding model, taking no consideration of the influence of temperature > ion size and electric field, and studies the characteristic of ion diffusion process with Monte Carlo simulation. Here we consider the effects of ion interaction and the numerary density of solute ion on diffusion coefficient. The results show that the diffusion coefficient of solute ion is constant without interactions; but when we consider the interactions, things become different. It has three cases: (i) when the numerary density of solute ion is not more than 0.2, the mean square displacement(MSD) is in line with Monte Carlo Step(MCS); (ii)when the numerary density of solute ion is among (0.2,0.6), the relation of MSD and MCS follows conic function; (iii) when the numerary density of solute ion approaches 1.0, MSD will get constant.Thirdly, this paper models the carrier number in silicon semiconductor by using the method of grand canonical ensemble and Fermi-Dirac statistical distributions. The simulation result shows that: (i)the carrier number enlarges with illuminationenergy increasing; (ii)when the illumination energy is low, temperature has little effect on carrier number, but when illumination energy gets higher, temperature has notable effect on carrier number, and carrier number gets more with temperature increasing. The result is coincident with academic rule. We may take this result as theoretical basis of doping semiconductor and oxide semiconductor.