Dehydrogenation of a single acetylene molecule on the Cu(111) surface

Dehydrogenation of acetylene molecules on metal surfaces is a crucial step in converting acetylene into carbon materials and other useful hydrocarbons for industrial applications. In this study, the dehydrogenation of a single acetylene molecule on a Cu(111) surface was investigated using scanning tunneling microscopy (STM) experiments and density functional theory (DFT) calculations. The dehydrogenation reaction, induced by applying a bias voltage pulse, transforms acetylene to C₂ without producing a detectable C₂H intermediate, in contrast to similar experiments on Cu(100) where a C₂H intermediate was detected. DFT calculations indicate that differences in molecule-surface interactions alter the reaction barrier for the two steps of dehydrogenation. The immediate reaction from acetylene to C₂ is driven by a lower reaction barrier for the second C-H bond dissociation compared to the first, along with the absence of an orientation change in the target molecule.