Modelling simple and complex metal-oxide and -hydroxide surface structures using their point of zero charge

Abstract

Multiple methods are available to measure organic and inorganic structures in an aqueous environment. These techniques though are mainly used for measuring and modelling the global structures of species in solution, molecules, polymers, biological compounds, and individual structure factors, not surfaces. Since surface structure and composition are directly responsible for a materials point of zero charge it is the ideal property for determining its global structure and composition. Multiple metal-oxides and -hydroxides in an aqueous environment, under varying conditions are also subject to changes in their surface structure and composition. Therefore, this work focuses solely on modelling the global surface structure of simple and complex metal-oxides and –hydroxides in an aqueous environment at their solid/liquid interface, as there are no other methods currently available for this task. The model developed for this work was obtained by augmenting a model originally used for predicting the point of zero charge for both simple and complex metal-oxides and –hydroxides using only their structure factors. To adapt the original model, it was necessary to determine not only each materials set of structure factors but also its surface properties (i.e. bond ionic content). The method then developed required a determination of each of the possible stable surface crystal structures at its point of zero charge (pH). Each of these structures was then placed in the model to determine which global structure converged to its experimental point of zero charge.