Electroreduction of CO₂ on Cu Clusters: The Effects of Size, Symmetry, and Temperature

Abstract

Copper is a potential electrocatalyst for CO 2 electroreduction, although controlling the selectivity towards hydrocarbons and CO is still a major challenge. It is known that Cu nanoparticles show a better performance for CO 2 electro-reduction than bulk Cu. However, the roles of the size and symmetry of the Cu clusters as well as the temperature in the CO 2 -reduction process remain elusive, which hinders the development of advanced catalysts. In this study, the density functional theory (DFT) method is applied to investigate these factors. We find that the decrease of icosahedron Cu clusters' size but the increase of truncated octahedron Cu clusters' size contributes to the selectivity of CO 2 reduction. In addition, the symmetry of Cu clusters modulates the selectivity of CO 2 reduction at room temperature: the (111)-like surfaces prefer to produce hydrocarbons but the synergistic effect between (100)-and (111)-like ones favors the formation of CO, which are in reasonable agreement with the experimental measurements that distinct products are detected on different Cu nanoparticles during CO 2 reduction. We also note that the increase of temperature is favorable to CO production. Our findings not only contribute to a thorough understanding of CO 2 reduction on Cu clusters, but also provide clues for designing catalysts in future experiments.[a] Dr.

Molecular Stabilization of Sub‐Nanometer Cu Clusters for Selective CO2 Electromethanation

“…This observation is consistent with the XRD results in which only ER−Cu(bipy)Br showed Cu crystal diffraction patterns. This also agrees with previous theoretical and experimental studies that show Cu nanoclusters are inclined to produce CH 4 while Cu nanoparticles are favorable for producing C 2+ [12–14] …”

“…This also agrees with previous theoretical and experimental studies that show Cu nanoclusters are inclined to produce CH 4 while Cu nanoparticles are favorable for producing C 2 + . [12][13][14] Sub-nanometer metal clusters have been used in catalysis due to their character of fully exposed catalytically active sites, but they are prone to agglomerate into energetically more stable, larger-size particles, losing their high activity and selectivity during catalytic turnovers. [48,49] Approaches to stabilizing the high-energy clusters have been developed and these include using metal-support interactions to immobilize on defective, porous carbon or metal oxides, as well as protecting with organic ligands.…”

“…Previous theoretical calculations predicted that the reaction energy for the hydrogenation of *CO is decreased when the coordination number of Cu is lowered or when the size of Cu is reduced. [12,13] Experimental advances agree with these predictions; [14][15][16][17] however, it is challenging to stabilize the active, under-coordinated nanoparticles or clusters, which are prone to aggregations under electrical bias used for driving CO2RR.…”

Screening of transition metal doped copper clusters for CO2 activation

“…65 For small (111)-like facets (Cu 13 , Cu 55 ) the hydrocarbon production is favourable, while synergetic effect between (100)-and (111)-like facets (Cu 38 , Cu 79 ) favours CO production. 66 Cu 3 , Cu 5 , and Cu 4 , Cu 6 exhibit similar CO 2 reduction mechanisms. The ratedetermining step is the cleavage of the adsorbed OH in the first case, while it is the proton-electron transfer to the adsorbed CO for the latter one.…”

Architectural Design for Enhanced C2 Product Selectivity in Electrochemical CO2 Reduction Using Cu-Based Catalysts: A Review

“…Particularly, the effects of size and symmetry of Cu clusters can significantly influence the catalytic activity and selectivity for the eCO 2 RR. 74 It is worth noting that either metal clusters or single atom catalysts tend to aggregate to larger particles, which is a major concern in the synthetic process. Therefore, well-designed synthetic methods are usually required to stabilize the clusters or single atoms against the aggregation and realize even distribution among a certain support.…”