Theoretical study on the reaction mechanism of reverse water–gas shift reaction using a Rh–Mo6S8 cluster

Abstract

The reverse water gas shift (RWGS) reaction catalyzed by a Rh–Mo₆S₈ cluster is investigated using density functional theory calculations. The reaction is explored along four possible mechanisms: one is the redox mechanism, another is the carboxyl mechanism, the third refers to the formic acid directly decomposing to CO, and the fourth involves the formation of a CHO intermediate. Thermodynamic and kinetic data are calculated to consider the catalysis cycle efficiency. Here, we perform the energetic span model (ESM) to investigate the kinetic behavior of the four catalytic cycles. Interestingly, it is shown that the direct decomposition of formic acid is the most suitable pathway for RWGS with the highest TOF value and lowest rate-determining energy barrier. We hope that our work will be beneficial to the development of RWGS.