Sustainable conversion of carbon dioxide to formic acid with Rh-decorated phosphorous-doped fullerenes: a theoretical study

We performed density functional calculations to study conversion of carbon dioxide to formic acid through designed catalyst of Rh-decorated phosphorous-doped fullerenes. Two paths of reaction are considered for this conversion. In the first pathway, CO2 is transferred to formate intermediate using the catalyst, and then, through a sequence of oxidative addition and reductive elimination reactions, formic acid is released; density functional theory results showed that in this path the oxidative addition is an easy and quite exothermic process. It is also shown that the rate-determining step in the hydrogenation of CO2 catalyzed by Rh-decorated phosphorous-doped fullerene complexes is the release of formic acid from formate intermediate. In the other pathway after the formation of rhodium formate intermediate and then addition of H2, the formic acid complex is released directly through metathesis process; our results showed a moderate energy barrier for the metathesis process, in which the oxidation state of the Rh center does not change. This barrier is found to be much smaller than the barrier of the reductive process in the first pathway.