Facet‐Selective Deposition of Ultrathin Al₂O₃ on Copper Nanocrystals for Highly Stable CO₂ Electroreduction to Ethylene

Abstract

Catalysts based on Cu nanocrystals (NCs) for electrochemical CO 2 -to-C 2+ conversion with high activity have been a subject of considerable interest, but poor stability and low selectivity for a single C 2+ product remain obstacles for realizing sustainable carbon-neutral cycles. Here, we used the facet-selective atomic layer deposition (FS-ALD) technique to selectively cover the (111) surface of Cu NCs with ultrathin Al 2 O 3 to increase the exposed facet ratio of (100)/(111), resulting in a faradaic efficiency ratio of C 2 H 4 /CH 4 for overcoated Cu NCs 22 times higher than that for pure Cu NCs. Peak performance of the overcoated catalyst (Cu NCs/ Al 2 O 3 -10C) reaches a C 2 H 4 faradaic efficiency of 60.4 % at a current density of 300 mA cm À2 in 5 M KOH electrolyte, when using a gas diffusion electrode flow cell. Moreover, the Al 2 O 3 overcoating effectively suppresses the dynamic mobility and the aggregation of Cu NCs, which explains the negligible activity loss and selectivity degradations of Cu NCs/Al 2 O 3 -10C shown in stability tests.

Structure‐Function Correlation and Dynamic Restructuring of Cu for Highly Efficient Electrochemical CO2 Conversion

“…As a result, the FE ratio of ethylene/methane on ALD‐coated Cu is 22 times higher than that on primitive Cu nanocrystals. Further experiments on a flow electrolyzer achieves a high ethylene FE of 60.4 % with a current density over 300 mA cm −2 and a negligible activity/selectivity degradation over 24 h at −1.1 V RHE [31] …”

“…Further experiments on a flow electrolyzer achieves a high ethylene FE of 60.4 % with a current density over 300 mA cm À 2 and a negligible activity/ selectivity degradation over 24 h at À 1.1 V RHE . [31] Beyond CO 2 R, facet engineering strategy is also widely explored in electrochemical CO reduction (COR) because CO is much favorable to yield high-valuable oxygenates. For instance, Cu nanowires synthesized by reducing pre-grown CuO nanowires presented a large amount of (110) sites and achieved a 50 % FE of ethanol at lower potentials.…”

Electrocatalytic Carbon Dioxide Reduction to Ethylene over Copper‐based Catalytic Systems

“…Stabilizing or increasing the exposure of special facets of catalyst, e. g., Cu(100) or some high‐Miller‐index facets, is an effective way to promote C 2 H 4 production [21,35,38–40] . In 1995, Hori et al.…”

“…Li et al. selectively covered the Cu(111) facet of Cu nanocrystals (Cu NCs) by depositing ultrathine Al 2 O 3 , thus improving the exposed facet ratio of Cu(100)/Cu(111) [35] . As the Cu(100) surface percentage of Cu NCs/Al 2 O 3 was 65%, the FE C2H4 reached 61% at −1.10 V versus RHE, higher than that over pristine Cu NCs with Cu(100) surface percentage of 41% (FE C2H4 =33%).…”

Oxygen Vacancy-Rich Amorphous Copper Oxide Enables Highly Selective Electroreduction of Carbon Dioxide to Ethylene

“…Ethylene (C2H4), one of the most critical hydrocarbons, is mainly produced by the cracking reaction of naphtha or the distillation of cracking gas [1][2][3] . Accordingly, great efforts have been made to develop an eco-friendly and cost-effective route for C2H4 production.…”