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) + H2(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 H2 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 H2 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 H2 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.