The effect of ferromagnetism on the CO activation over FCC crystal phase transition metal catalysts: Insights from DFT calculations

Abstract

In order to understand the relationship between the ferromagnetism and catalytic performance, three pathways of CO activation over transition metal catalysts (Co, Ni, Cu, Rh, Pd, Ag, Ir, Pt, and Au) have been studied by using density functional theory (DFT) calculations. It is shown that Co and Ni metal catalysts have better catalytic performance for CO activation than others. The density of states (DOS) and spin density plots reveal that Co and Ni metal possess ferromagnetism. So it is concluded that the catalytic activity connects with the metal ferromagnetism. To further confirm this deduction, the magnetic moments and Bader charge have been calculated when small molecules (CO, CHO, and COH) adsorbed on the Co and Ni metal surface, and the results shows that the electron transfer between the small molecules and metal catalysts happens on the unpaired d-orbital electrons (nd) of the metal, which changes the magnetic moments of Co and Ni metal. Meanwhile, electron transfer also changes the catalytic performance of Co and Ni metal catalysts. Compared with the CO, the electron transfer of CHO and COH is more, the magnetic moments of metal changes greatly, and the carbon-oxygen bonds of CHO and COH are easier to break. So the magnetic moments of metal catalysts can be used as an indicator to select different metal catalysts.