Formaldehyde adsorption on a hydrogenated aluminum nitride monolayer: a self-propagated reaction

Publication date: Available online 13 May 2019Source: Computational and Theoretical ChemistryAuthor(s): Alejandro Noguerón, Noé Fernández-Escamilla, Jonathan Guerrero-Sánchez, Noboru TakeuchiAbstractUsing density functional theory calculations, we have studied the functionalization, with formaldehyde, of a hydrogenated hexagonal aluminum nitride (h-AlN) monolayer. The reaction begins with the formaldehyde chemisorption on a hydrogen vacancy of the Al side of the monolayer. This strong interaction is due to the reactive surface dangling bond and it results in a partial breaking of the C=O double bond. The energy gain by adsorbing on the aluminum side of the monolayer is larger than on the nitrogen side. After the attachment of formaldehyde on an Al site, the molecule turns into a highly reactive radical. The next step of the reaction is the abstraction of a neighbor H atom from the monolayer, generating a new dangling bond on the sheet where the next molecule can attach. This process can be repeated, triggering a chain reaction, which ends up with a full formaldehyde monolayer. Our results show that this reaction is highly probable, since the energy barrier to abstract the H atom is 0.31 eV, 1.89 eV lower than the one needed to desorb the formaldehyde molecule from the sheet. Electronic properties are described in order to understand the main states of the reaction. In particular, it shows a reduction of the band gap upon the adsorption of the aldehyde molecule. This resul...

Source: Computational and Theoretical Chemistry - May 14, 2019 Category: Chemistry Source Type: research