Synergistic core–shell interactions enable ultra-low overpotentials for enhanced CO2 electro-reduction activity

Abstract

Carbon dioxide is a major culprit of climate change, dramatically warming the Earth with its accumulation in the atmosphere. Converting CO₂ to high end fuels could potentially solve environmental problems and create a sustainable energy cycle. In spite of Cu being the most successful catalyst capable of producing hydrocarbons from CO₂, its efficiency suffers from high overpotentials, which originate from the highly endothermic CO protonation to CHO. Using density functional theory (DFT), we optimize the composition of a bimetallic core TM_xNi_13−x (TM = 3d transition metals; x = 3, 6, and 9) encapsulated in a 42 atom Cu icosahedral shell to lower the CO₂ reduction overpotential. On Sc₅₍₆₎Ni₈₍₇₎–Cu₄₂, this overpotential reduces to an unprecedented value of ∼0.17 V below the standard potential value (SPV). These specific core compositions optimize the position of the d-band center of the shell, required for better interaction with CHO π orbitals than CO, giving exergonic CO reduction. The estimated statistical coverage of CHO exceeds 60% under ambient conditions on Sc₆Ni₇–Cu₄₂, which will promote CO₂ conversion to the high end fuel CH₄ without CO poisoning of the catalyst. The effect of implicit solvent is found to be marginal on the stability, reaction barriers and overpotentials, ensuring the robustness of Sc₅₍₆₎Ni₈₍₇₎–Cu₄₂ for efficient CO₂ electro-reduction.