Dual-Facet Mechanism in Copper Nanocubes for Electrochemical CO₂ Reduction into Ethylene

Abstract

The product selectivity in the electrochemical reduction of carbon dioxide depends on the structure of the copper electrode. Cube-shaped copper catalysts, enclosed by {100} terraces, {110} edges, and {111} corners, exhibit a size-dependent enhanced only selectivity toward C 2 products and ethylene in particular. However, the underlying chemical reasons for such a behavior are not fully understood. This computational work toward ethylene formation investigates the carbon dioxide electroreduction mechanism over copper nanocubes. The analysis of the different pathways illustrates that the thermodynamic picture is limited in describing the formation of this product. Based on the activation barriers associated with the limiting C 2 formation step, we identify a dual-facet mechanism occurring at the interface between the {100} terraces and {110} edges. These results highlight that the reactivity of shape-controlled nanocatalysts goes beyond the facet-selectivity observed in single crystals owing to the possible synergies arising at the intersection between the enclosing crystalline planes.

Stability and Degradation Mechanisms of Copper‐Based Catalysts for Electrochemical CO2 Reduction

“…3D electron tomography (Figure C) shows that the CuNCs undergo a pitting process, leaving tiny pinholes at the edges of the cube. This result is consistent with the theoretical findings that the edge/facet interface is the most active for C−C coupling …”

Stability and Degradation Mechanisms of Copper‐Based Catalysts for Electrochemical CO2 Reduction

“…This result is consistent with the theoretical findings that the edge/ facet interface is the most active for C À C coupling. [45] Moreover, additional experiments were performed to investigate the effect of CO 2 adsorption and applied negative potential separately. DFT calculations of the surface energy of different Cu facets under applied potential were performed and thermodynamically stable shapes were predicted using the Wulff construction.…”

Imaging electrochemically synthesized Cu2O cubes and their morphological evolution under conditions relevant to CO2 electroreduction

“…Therefore, there has been significant research into ways to engineer the detailed structure of NPs in order to create electrocatalysts with improved activity and selectivity for various electrochemical reactions. In particular, designing an effective electrocatalyst for the selective reduction of CO 2 (CO 2 RR) into valuable products, such as ethylene or ethanol [4][5][6] , is still an ongoing challenge. CO 2 RR powered by renewable energy sources is an attractive strategy for the sustainable production of chemicals and fuels.…”