Formic Acid Synthesis in a Water-Mineral System: Major Role of the Interface

Mineral surfaces are known for their catalytic properties, as they have lower kinetic barriers to reactions and modify chemical equilibria. Using ab initio molecular dynamics and enhanced sampling methods, we predict that the MgO(001)-water interface thermodynamically favors the formation of formic acid from carbon monoxide and water. This occurs despite the lack of direct participation from the surface atoms, with the reaction taking place beyond the first adsorbed layer. Furthermore, the application of an external electric field on the reaction in bulk water shows a similar effect. We propose that formic acid may be stabilized by the surface electric field, by direct comparison with the equilibrium in bulk water with and without an external electric field applied, and at the MgO(001)-water interface.