Enhancing CO2 Electroreduction by Tailoring Strain and Ligand Effects in Bimetallic Copper–Rhodium and Copper–Nickel Heterostructures

We show how epitaxially grown Cu–Rh and Cu–Ni heterostructures exploit the strain effect, due to the lattice mismatch, and the ligand effect, arising from the electronic interaction between the heterolayers, to achieve improved CO2 electroreduction. In this study we have performed density functional calculations on Cui/Mj/Cu(211) sandwiched surfaces and Cui/M(211) overlayers (where M = Rh or Ni, with varied i and j monolayers). We examined the free energy profiles of the reaction mechanisms for CO2 reduction to CO and CH4. We find that in Cu1/M1/Cu(211), in which the Cu monolayer experiences only a pure ligand effect, the influence of Ni is weaker than Rh and it decreases the overpotential for CO2 reduction by ∼10–20 mV. A larger decrease (33–64 mV) in the overpotential is predicted for other sandwiched surfaces: Cu1/Ni2/Cu(211), Cu2/Rh1/Cu(211), and Cu2/Rh2/Cu(211) in which the ligand effect is weaker. In the Cu1/M(211) overlayer, Cu is affected by both the strain and ligand effects, of which the latter ...