Computational study of proton binding at the rutile/electrolyte solution interface

Quantum chemistry methods are used to study the properties (charges, proton affinity constants) of isolated surface sites originating from (100), (110), and (001) rutile surfaces. Energetic profiles of water adsorption on rutile suggest that the dissociative adsorption is energetically favorable, so surface hydrolysis is a probable mechanism of rutile surface charging. Moreover, on the basis of energetic profiles of proton binding we conclude that this process is exothermic with the highest heat effect at (110) surface. The ab initio results are compared with the multisite complexation model predictions, and next they are used as input data for the grand canonical Monte Carlo simulations of proton binding, which are carried out to predict the adsorption isotherms for isolated unreconstructed and reconstructed surfaces. The solvent effects are modeled using the conductor-like screening model for real solvents model in the ab initio calculations and the Borkovec potential in the Monte Carlo simulations.