Mechanistic Insights into Vacancy-Driven Activation and Dissociation of Hydrogen Peroxide on Ti₃C₂O₂ MXene in Water

Abstract

Comprehending peroxide activation at solid-liquid interfaces is essential for energy conversion, environmental cleanup, and catalysis. In this work, we use advanced electronic analyses, ab initiomolecular dynamics (AIMD)-driven machine-learned force fields (MLFFs), and DFT+U computations to investigate the interaction of H₂O₂ with both pure and oxygen-defective Ti₃C₂O₂ MXene in specific aquatic environments. Because of the poor hydrogen bonding (-0.41 eV) and minimal charge transfer during adsorption on pristine surfaces, the O-O bond stays electrically intact and catalytically inert. Oxygen vacancies, on the other hand, provide extremely reactive centers where unsaturated Ti atoms cause significant charge transfer (1.13 e), significantly chemisorb H₂O₂ (-5.03 eV), and promote spontaneous O-O bond breaking. The peroxide bond is destabilized by vacancy-derived Ti-d states, according to electronic structure investigations, whereas electron localization function (ELF) mapping shows how charge is redistributed during bond breakage and fragment stabilization. According to long-timescale AIMD-MLFF simulations, explicit water molecules also promote breakdown by permitting solvent-mediated proton shuttling. NEB simulations verify a low kinetic barrier (~0.61 eV), suggesting that dissociation is accessible kinetically and thermodynamically in ambient settings. Together, these findings demonstrate the effectiveness of defect engineering as a lever to stimulate inert MXenes toward peroxide breakdown and the complementary nature of MLFFs and DFT+U in atomistic fidelity resolution of intricate aqueous chemical pathways.