Influence of HCOO- on Calcite Growth from First-Principles

Organic molecules in aqueous solutions are good candidates in the inhibition of some biogenic crystal growth. The formic acid HCOOH is considered to investigate at an atomic level the interaction between the carboxyl functional group -COO- and the (10 (1) over bar4) hydrated surface of calcium carbonate, CaCO3, in the form of calcite. Ab initio simulations based on the density functional theory are performed to study the adsorption of undissociated and dehydrogenated HCOOH in the presence of water. Relevant adsorption energies obtained for HCOO- + H2O on calcite predict that water is essential in the stabilization of the carboxyl group in its deprotonated form. The interfacial properties and the trend of adsorption energies for different coverages are given in detail. The dissociation barriers of HCOOH on hydrated calcite are evaluated with the climbing-image nudged elastic band (CI-NEB) method.