The role of sub-surface hydrogen on CO₂ reduction and dynamics on Ni(110): An ab initio molecular dynamics study

The catalytic reduction in carbon dioxide is a crucial step in many chemical industrial reactions, such as methanol synthesis, the reverse water-gas shift reaction, and formic acid synthesis. Here, we investigate the role of bulk hydrogen, where hydrogen atoms are found deep inside a metal surface as opposed to subsurface ones, upon CO₂ reduction over a Ni(110) surface using density functional theory and ab initio molecular dynamics simulations. While it has previously been shown that subsurface hydrogen stabilizes CO₂ and can aid in overcoming reaction barriers, the role of bulk hydrogen is less studied and thus unknown with regard to CO₂ reduction. We find that the presence of bulk hydrogen can significantly alter the electronic structure of the Ni(110) surface, particularly the work function and d-band center, such that CO₂ adsorbs more strongly to the surface and is more easily reduced. Our results show an enhanced CO₂ dissociation in the presence of bulk hydrogen, shedding light on a hitherto underappreciated mechanistic pathway for CO₂ reduction on metal surfaces.