Coordination polymer design for fast proton conduction: Hybrid atomistic approach based on kinetic Monte Carlo and molecular dynamics methods

Abstract

Fast proton conductors are important materials for catalysis and energy conversion applications. The glassy coordination polymers are an important class of proton conductors due to their good mechanical moldability; however, their conductivity has been limited to ca. 10 mS cm−1 at 100 °C. The systematic design of coordination polymers with fast proton conduction requires an atomistic simulation method that can describe long-range proton diffusion within an affordable computational time. The methodologies of atomistic simulations are separately limited and cannot fairly describe the long-range proton conduction in non-crystalline materials. In this work, we develop a hybrid approach that combines the molecular dynamics based on a conventional force-field and the kinetic Monte Carlo method, which allows for the large-scale (thousands of atoms) and long time (few nanoseconds) simulation of the long-range ionic diffusion in non-crystalline materials. Based on the developed approach, we propose and confirm a design concept for a fast proton-conducting coordination polymer based on Zn2+ ions and phosphoric acid.