Reaction mechanism of methanol on 4H-SiC substrate surface: a density functional theory study

Abstract

In this study, density functional theory (DFT) methods were employed to systematically investigate the adsorption, dissociation, and subsequent reaction pathways of methanol molecules (CH₃OH) on the C-terminated surface and Si-terminated face of silicon carbide (SiC) cluster models. By optimizing geometric structures, tracing reaction pathways and transition states, analyzing electronic density of states, strong and weak interactions, and bond orders, the detailed reaction mechanisms of methanol molecules on different surfaces of SiC were revealed. The research found that methanol molecules undergo dissociative adsorption on both the Si-terminated surface and C-terminated surface of SiC, with two dissociative pathways existing due to variations in adsorption sites or external conditions. The Si-terminated surface is more reactive compared to the C-terminated surface. These findings provide atomistic insights into surface reactivity, guiding the design of non-aqueous slurries for efficient SiC chemical mechanical polishing (CMP).