Enhanced Electrochemical Methanation of Carbon Dioxide at the Single-Layer Hexagonal Boron Nitride/Cu Interfacial Perimeter

The electrochemical conversion of CO₂ to valuable fuels is a plausible solution to meet the soaring need for renewable energy sources. However, the practical application of this process is limited by its poor selectivity due to scaling relations. Here we introduce the rational design of the monolayer hexagonal boron nitride/copper (h-BN/Cu) interface to circumvent scaling relations and improve the electrosynthesis of CH₄. This catalyst possesses a selectivity of >60% toward CH₄ with a production rate of 15 μmol·cm^-2·h^-1 at -1.00 V vs RHE, along with a much smaller decaying production rate than that of pristine Cu. Both experimental and theoretical calculations disclosed that h-BN/Cu interfacial perimeters provide specific chelating sites to immobilize the intermediates, which accelerates the conversion of *CO to *CHO. Our work reports a novel Cu catalyst engineering strategy and demonstrates the prospect of monolayer h-BN contributing to the design of heterostructured CO₂ reduction electrocatalysts for sustainable energy conversion.