Adsorption and infrared spectra simulations of acrylic acid over (001) surface of molybdenum carbide

Abstract

Molybdenum carbide (Mo2C) can be employed as catalyst and the nature of the active sites and reactants are often investigated by adsorption of probe molecules, applying infrared spectroscopy (IR). However, IR analysis is a complex task and theoretical simulations can help. In order to study the adsorption and IR analysis of acrylic acid over Mo2C, we have performed DFT calculations and compared to the experimental results. Radical and dimer formation on the carbide surface were also considered. It was shown that the energetic selection is not enough to rationalize the experimental IR spectrum. The most favorable specie is the adsorbed acrylic acid in the parallel mode. In the limit of dimer formation, the hydrogen bonds great stabilize the parallel adsorption. On the other hand, simulated IR spectra are compatible to parallel dimer as well as parallel and orthogonal monomers. Finally, we identified three possible desorption pathways indicating different desorption temperatures.