CO Adsorption over 3 Transition-Metal Nanoclusters Supported on Pyridinic N-Doped Graphene: A DFT Investigation.

CO adsorption on bare 3 transition-metal nanoclusters and 3 transition-metal nanoclusters supported on pyridinic N-doped graphene (PNG) was investigated by employing the density functional theory. First, the interaction of Co and Cu with PNG was analyzed by spin densities, interaction energies, charge transfers, and HUMO-LUMO gaps. According to the interaction energies, the Co nanocluster was adsorbed more efficiently than Cu on the PNG. The charge transfer indicated that the Co nanocluster donated more charges to the PNG nanoflake than the Cu nanocluster. The HUMO-LUMO gap calculations showed that the PNG improved the chemical reactivity of both Co and Cu nanoclusters. When the CO was adsorbed on the bare 3 transition-metal nanoclusters and 3 transition-metal nanoclusters supported on the PNG, it experienced a bond elongation and angle bending in both systems. In addition, the charge transfer from the nanoclusters to the CO molecule was observed. This study proved that Co/PNG and Cu/PNG composites are adequate candidates for CO adsorption and activation.