Manipulating local coordination of copper single atom catalyst enables efficient CO ₂-to-CH ₄ conversion

Abstract

Electrochemical CO ₂ conversion to methane, powered by intermittent renewable electricity, provides an entrancing opportunity to both store renewable electric energy and utilize emitted CO ₂. Copper-based single atom catalysts are promising candidates to restrain C-C coupling, suggesting feasibility in further protonation of CO* to CHO* for methane production. In theoretical studies herein, we find that introducing boron atoms into the first coordination layer of Cu-N ₄ motif facilitates the binding of CO* and CHO* intermediates, which favors the generation of methane. Accordingly, we employ a co-doping strategy to fabricate B-doped Cu-N _x atomic configuration (Cu-N _x B _y ), where Cu-N ₂B ₂ is resolved to be the dominant site. Compared with Cu-N ₄ motifs, as-synthesized B-doped Cu-N _x structure exhibits a superior performance towards methane production, showing a peak methane Faradaic efficiency of 73% at −1.46 V vs. RHE and a maximum methane partial current density of −462 mA cm ⁻² at −1.94 V vs. RHE. Extensional calculations utilizing two-dimensional reaction phase diagram analysis together with barrier calculation help to gain more insights into the reaction mechanism of Cu-N ₂B ₂ coordination structure.

Abstract

Developing efficient electrocatalysts for selective CO2 conversion is of high interest. Here the authors investigate B doped Cu single atom catalysts with Cu-N2B2 coordination for enhanced CO2 to CH4 conversion.