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Regulating the selectivity toward a target hydrocarbon product is still the focus of CO2electroreduction. Here, we discover that the original surface Cu species in Cu gas‐diffusion electrodes plays a more important role than the surface roughness, local pH, and facet in governing the selectivity toward C1or C2hydrocarbons. The selectivity toward C2H4progressively increases, while CH4decreases steadily upon lowering the Cu oxidation species fraction. At a relatively low electrodeposition voltage of 1.5 V, the Cu gas‐diffusion electrode with the highest Cuδ+/Cu0ratio favors the pathways of hydrogenation to form CH4with maximum Faradaic efficiency of 65.4% and partial current density of 228 mA cm−2at −0.83 V vs RHE. At 2.0 V, the Cu gas‐diffusion electrode with the lowest Cuδ+/Cu0ratio prefers C–C coupling to form C2+products with Faradaic efficiency topping 80.1% at −0.75 V vs RHE, where the Faradaic efficiency of C2H4accounts for 46.4% and the partial current density of C2H4achieves 279 mA cm−2. This work demonstrates that the selectivity from CH4to C2H4is switchable by tuning surface Cu species composition of Cu gas‐diffusion electrodes.
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Planar defect-driven electrocatalysis of CO 2 -to-C 2 H 4 conversion
The selectivity towards a specific C 2+ product, such as ethylene (C 2 H 4 ), is sensitive to the surface structure of copper (Cu) catalysts in carbon dioxide (CO 2 ) electro-reduction. The fundamental understanding of such sensitivity can guide the development of advanced electrocatalysts, although it remains challenging at the atomic level. Here we demonstrated that planar defects, such as stacking faults, could drive the electrocatalysis of CO 2 -to-C 2 H 4 conversion with higher selectivity and productivity than Cu(100) facets in the intermediate potential region (−0.50 ∼ −0.65 V vs. RHE). The unique right bipyramidal Cu nanocrystals containing a combination of (100) facets and a set of parallel planar defects delivered 67% faradaic efficiency (FE) for C 2 H 4 and a partial current density of 217 mA cm −2 at −0.63 V vs. RHE. In contrast, Cu nanocubes with exclusive (100) facets exhibited only 46% FE for C 2 H 4 and a partial current density of 87 mA cm −2 at an identical potential. Both ex situ CO temperature-programmed desorption and in situ Raman spectroscopy analysis implied that the stronger *CO adsorption on planar defect sites facilitates CO generation kinetics, which contributes to a higher surface coverage of *CO and in turn an enhanced reaction rate of C–C coupling towards C 2+ products, especially C 2 H 4 .
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- Award ID(s):
- 2033343
- PAR ID:
- 10286533
- Date Published:
- Journal Name:
- Journal of Materials Chemistry A
- ISSN:
- 2050-7488
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1039/d1ta02565a
