Identification of Cu/Sc and Cu/Ti subsurface alloys for highly efficient CO electroreduction to C2 products

Abstract

The electroreduction of CO to C2 products (primarily C2H4 and EtOH) provides a promising route to both carbon neutrality and energy storage and conversion under mild conditions. However, the commonly used copper catalyst suffers from high overpotentials, which has been shown to be closely related to CO dimerization reaction. Using density functional theory calculations, we study the effect of composition and structure of CuM(100) surface (M = Ru, Au, Zn and Ga) and Cu/M(100) subsurface (M = 3d Sc-Zn) alloys on the relative stability of 2CO and C2O2. We show that the higher stability of C2O2 relative to 2CO and enhanced CO electroreduction activity are achieved through increasing the interlayer separation of Cu (100) by the presence of subsurface Sc and Ti, which decrease the overlap between the dz2 orbitals of surface Cu and subsurface atoms and destabilizes the σ bond of Cu–CO more than that of Cu–C2O2. This modification also largely facilitates the C2H4 formation instead of EtOH formation through a substantial stabilization of the adsorbed intermediates. This work opens up an avenue for the design and development of catalyst in CO/CO2 electroreduction and other important reactions of technological interest.