Quantitative Analysis of DCET and DAT Pathways in the H/D Exchange of Aniline on Pt(111) Using D ₂ O as the Deuterium Source

Hydrogen–deuterium exchange (H/D exchange) reactions, which are highly efficient isotope-labeling techniques, have become widely applied across various industries. However, the detailed reaction mechanisms have remained inadequately explored. In this study, we use density functional theory (DFT) combined with experimental characterization to investigate the deuteron-coupled electron transfer (DCET) and deuterium-atom transfer (DAT) pathways in the H/D exchange of aniline on Pt(111), utilizing D2O as the deuterium source. We developed both coverage-dependent and coverage-independent kinetic models to explore the impact of adsorbate–adsorbate interactions on reaction pathway selection and rate. Our results demonstrate that the coverage-dependent model provides a more accurate representation of the reaction environment. Microkinetic simulations further confirm that the process is thermodynamically driven with the deuteration predominantly occurring through the DAT pathway. Additionally, we show that the temperature plays a crucial role in accelerating the reaction rate, highlighting its significance as a key factor in controlling the reaction kinetics.