Disilane (Si2H6) is a key substance for chemical industries designing semiconductors and graphene materials. Its reaction mechanism is, however, still elusive, as evident from serious chemical accidents when exposed to open air. Using first-principles density functional theory calculations, we investigate the thermodynamic and kinetic mechanisms of Si2H6 hydrolysis, with and without oxidative conditions of adjacent water, oxygen gas and metallic Fe particulates. Despite the remarkable thermodynamic spontaneity, direct hydrolysis is kinetically sluggish due to the high energy barrier. Hydrolysis initiated by O2 is identified with a multi-step radical mechanism, which is kinetically more favored than the direct hydrolysis. The energy barrier of rate-determining step is, however, still too high for Si2H6 to react in a humid and oxidative environment. Surprisingly, we report that metallic iron serves as an of interest heterogeneous catalyst for the Si2H6 hydrolysis dramatically lowing the activation energy barrier for the dissociation. Our results propose that fine air particulates including Fe can play a key role in facilitating the explosive reaction of Si2H6 potentially leading to severe chemical accidents, otherwise very inert.
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© 2021 Elsevier B.V.
All Science Journal Classification (ASJC) codes
- Condensed Matter Physics
- Surfaces, Coatings and Films
- Surfaces and Interfaces