A First-Principles Study of CO 2 Hydrogenation on a Niobium-Terminated NbC (111) Surface

As promising materials for the reduction of greenhouse gases, transition-metal carbides, which are highly active in the hydrogenation of CO , are mainly considered. In this regard, the reaction mechanism of CO hydrogenation to useful products on the Nb-terminated NbC (111) surface is investigated by applying density functional theory calculations. The computational results display that the formation of CH , CH OH, and CO are more favored than other compounds, where CH is the dominant product. In addition, the findings from reaction energies reveal that the preferred mechanism for CO hydrogenation is thorough HCOOH , where the largest exothermic reaction energy releases during the HCOOH dissociation reaction (2.004 eV). The preferred mechanism of CO hydrogenation towards CH production is CO →t,c-COOH →HCOOH →HCO →CH O →CH OH →CH →CH →CH , where CO →t,c-COOH →HCOOH →HCO →CH O →CH OH →CH OH and CO →t,c-COOH →CO are also found as the favored mechanisms for CH OH and CO productions thermodynamically, respectively. During the mentioned mechanisms, the hydrogenation of CH O to CH OH has the largest endothermic reaction energy of 1.344 eV.