DFT study of methanol adsorption on PtCo(111)

Highlights: • Methanol is adsorbed on a FCT PtCo surface on top of Co atom with an O−Co distance of 2.24 Å. • C−O−Co angle is 142° and the C−O−H angle is about 111°. • The C−O and O−H bonds show a small elongation whereas the C−H bonds are shortened. • The charge transfer seems to occur from C atom to O atom, and then to the Co₁ atom (surface). • The Co−O calculated frequency is 250 cm⁻¹, which is similar to the experimentally reported. - Abstract: Methanol adsorption on PtCo(111) surface at low coverage is studied using Density Functional Theory (DFT) calculations without and with van der Waals corrections. We investigated the PtCo FCT alloy surface with a uniform distribution. The most favorable site for CH₃OH adsorption is on top of a Co atom, with an adsorption energy of −0.92 eV. Methanol attachs to the surface by the O atom, with a distance of 2.24 Å. The molecule presents a small distortion after adsorption. The C−O−Co bond angle is 142°. The C−H bonds are strengthened whereas the C−O and O−H bonds are weakened. A charge transfer from C atom to O atom occurs upon adsorption, and then further transfer occurs to the Co atom on the surface. The calculated vibrational frequencies for adsorbed methanol present a red-shift displacement compared to gas-phase, confirming the adsorption process.