AI-guided ab initio molecular dynamics study of proton migration in a hydrated MOF for PEMFC applications

Abstract

Proton exchange membrane fuel cells (PEMFCs) have recently garnered attracted considerable attention due to their low operating temperatures and high energy conversion efficiencies. In this work, we theoretically demonstrate that a novel three-dimensional sodium-based metal-organic framework (MOF UAX-2) exhibits high proton migration conductivity. Sodium-based MOFs are rare, as the coordinated solvent molecules that bind to sodium ions often lead to structural collapse upon activation, as these solvents are removed. Remarkably, MOF UAX-2 retains its structural, thermal, dynamic, and mechanical stability at and above room temperature. The mechanism of proton transport within the MOF was investigated using ab initio molecular dynamics (AIMD) simulations, employing the Verlet integration algorithm as implemented in the SIESTA software package. Simulations were conducted across various temperatures, proton locations, and initial velocities conditions. This study proposes MOF UAX-2 as a promising candidate for use as a proton exchange membrane (PEM) in next-generation fuel cell technologies. • AIMD with Verlet algorithm confirms thermal stability and rapid proton migration temperatures up to 1000 K. • Unique 4,4,7-c rod-net topology identified via TOPOSPRO analysis. • BVSE analysis maps 3D proton pathways with low 0.72 eV energy barrier. • Optical and magnetic data support multifunctionality for PEMFC applications. • STM simulation shows magnetic ordering and spin-polarized charge density.