DFT Study of Catalytic CO2 Hydrogenation over Pt-Decorated Carbon Nanocones: H2 Dissociation Combined with the Spillover Mechanism

In this work, we investigate the catalytic role of platinum-decorated defective CNC (Pt/dCNC) in CO2 hydrogenation to formic acid (FA) by a density functional theory (DFT) approach. The reaction follows the equation CO2(g) + H-2(g) -> HCOOH(g). Combining highly reactive Pt atoms with defective CNC provides Pt/dCNC, a reactive monodispersed atomic catalyst for CO2 hydrogenation. We propose our new mechanism of CO2 hydrogenation over the Pt/dCNC catalyst involving a H-2 dissociation and H spillover sequence that is energetically favorable. The rate-determining step is formic acid desorption that requires an energy barrier of 1.11 eV. Furthermore, our findings show that the rate of FA production is dependent on H-2 concentration. Altogether, the theoretical results support the concept of the spillover mechanism, playing a key role in promoting CO2 hydrogenation via a formate intermediate. These results improve our understanding of the mechanism involving H-2 dissociation with the H spillover process and the catalytic reactions that are very important for the development of highly efficient catalysts for CO2 conversion into FA.