Highly Tensile Strained Cu(100) Surfaces by Epitaxial Grown Hexagonal Boron Nitride for CO Electroreduction to C Products.

Copper (Cu) has been considered as the most promising catalyst for the electrochemical conversion of CO to multicarbon (C) products. However, insufficient coverage of the *CO intermediate on the C formation Cu(100) facet largely hinders the C-C coupling process and thus the C conversion efficiency. Herein, we developed an epitaxial growth strategy to generate highly tensile-strained Cu(100) facets via the epitaxial growth of hexagonal boron nitride (hBN) on Cu(100) facets to promote *CO coverage for efficient CO to C conversion. The highest ∼6% tensile strain on the Cu(100) facets was obtained by lattice mismatch between the Cu(100) and hBN(002) facets. Theory calculations indicated that tensile-strained Cu(100) facets deliver a notable -band center upshift to enhance *CO adsorption. As a result, the obtained highly tensile-strained Cu(100) facets enabled an 8-fold improvement of *CO coverage and thus a 83.4% C Faradaic efficiency at 1.2 A cm in strongly acidic electrolyte (pH = 1).