A Computational Investigation of the Catalytic Properties of Graphene Oxide: Exploring Mechanisms Using DFT Methods

TL;DR

This study uses DFT calculations to uncover how graphene oxide catalyzes oxidation reactions, revealing mechanisms involving epoxide groups and oxygen recharging, explaining its unique reactivity compared to graphite.

Contribution

It provides a detailed mechanistic understanding of graphene oxide's catalytic activity using computational DFT methods, highlighting the role of epoxide groups and oxygen recharging.

Findings

Epoxide groups facilitate hydrogen transfer and ring-opening reactions.

Graphene oxide can be recharged by molecular oxygen, enabling catalyst turnover.

Graphene oxide has lower reaction barriers than graphite, explaining its catalytic efficiency.

Abstract

Here we describe a computational study undertaken in an effort to elucidate the reaction mechanisms behind the experimentally observed oxidations and hydrations catalyzed by graphene oxide (GO). Using the oxidation of benzyl alcohol to benzaldehyde as a model reaction, density functional theory (DFT) calculations revealed that this reactivity stemmed from the transfer of hydrogen atoms from the organic molecule to the GO surface. In particular, neighbouring epoxide groups decorating GO's basal plane were ring-opened, resulting in the formation of diols, followed by dehydration. Consistent with the experimentally-observed dependence of this chemistry on molecular oxygen, our calculations revealed that the partially reduced catalyst was able to be recharged by molecular oxygen, allowing for catalyst turnover. Functional group-free carbon materials, such as graphite, were calculated to have substantially higher reaction barriers, indicating that the high chemical potential and rich functionality of GO are necessary for the observed reactivity.