Atomic‐Scale Spacing between Copper Facets for the Electrochemical Reduction of Carbon Dioxide
Hyung Mo Jeong, Youngkook Kwon, Jong Ho Won, Yanwei Lum, Mu‐Jeng Cheng, Kwang Ho Kim, Martin Head‐Gordon, Jeung Ku Kang
Abstract
Abstract Copper (Cu) offers a means for producing value‐added fuels through the electrochemical reduction of carbon dioxide (CO 2 ), i.e., the CO 2 reduction reaction (CO 2 RR), but designing Cu catalysts with significant Faradaic efficiency to C 2+ products remains as a great challenge. This work demonstrates that the high activity and selectivity of Cu to C 2+ products can be achieved by atomic‐scale spacings between two facets of Cu particles. These spacings are created by lithiating CuO x particles, removing lithium oxides formed, and electrochemically reducing CuO x to metallic Cu. Also, the range of spacing ( d s ) is confirmed via the 3D tomographs using the Cs‐corrected scanning transmission electron microscopy (3D tomo‐STEM), and the operando X‐ray absorption spectra show that oxidized Cu reduces to the metallic state during the CO 2 RR. Moreover, control of d s to 5–6 Å allows a current density exceeding that of unmodified CuO x nanoparticles by about 12 folds and a Faradaic efficiency of ≈80% to C 2+ . Density functional theory calculations support that d s of 5–6 Å maximizes the binding energies of CO 2 reduction intermediates and promotes C–C coupling reactions. Consequently, this study suggests that control of d s can be used to realize the high activity and C 2+ product selectivity for the CO 2 RR.