Exploring Si-centered phthalocyanine as a single atom catalyst for NO reduction: a DFT study.

To remove the greenhouse gas NO from the environment, recently, researchers have taken great interest in single-atom catalysts (SACs). In this study, we investigated various reaction pathways and barrier energies for the NO reduction process onto Si-coordinated phthalocyanine (Si@PthC) employing density functional theory. The outcomes validate that Si decoration in PthC is energetically stable while the corresponding electronic properties show that the Si atom acts as the reactive site for catalytic activity. The NO molecule exhibits spontaneous dissociation over the catalyst surface from the O-end with -4.01 eV dissociation energy. Meanwhile, NO dissociation the N-end involves chemisorption onto the Si@PthC surface with an adsorption energy () of -1.16 eV, and the dissociation needs an energy barrier of 0.51 eV. The bond distances and negative adsorption energies (-1.11 and -2.40 eV) evince that CO and O species chemisorbed onto the Si@PthC surface. However, these energies are smaller than the NO dissociation energy, which demonstrates that the presence of CO and O molecules cannot interrupt the NO reduction process. Additionally, the CO + O* → CO reaction was executed for catalyst recovery, and the reaction proceeds very quickly on the Si@PthC catalyst, with a very small energy barrier (0.37 eV), indicating the excellent catalytic reactivity of the studied catalyst. These results propose that the designed catalyst can be valuable in the progress of novel noble metal-free catalysts for the elimination of harmful NO from the environment.