Apr 24, 2024
11:30am - 11:45am
Room 337, Level 3, Summit
Seolha Lim1,Woosuck Kwon1,Dae-Hyun Nam1
Daegu Gyeongbuk Institute of Science and Technology1
Electrochemical carbon dioxide reduction reaction (CO
2RR) is promising in the pursuit of carbon neutrality, as it converts CO
2, the primary contributor to global warming, into valuable high-end fuels and chemical feedstocks. Copper (Cu) is the only metal that has an appropriate *CO binding energy for C-C coupling. Cu-based CO
2RR electrocatalysts can produce multi-carbon (C
2+) chemicals such as ethylene, ethanol, and acetic acid. Nonetheless, they suffer from low selectivity for producing specific products. Particularly, bimetallic systems including Cu with secondary metals such as Au and Ag for their weak *CO bonds, emerge as a promising strategy to enhance the production of C
2+ chemicals. However, the focus of Cu-based bimetallic catalysts has primarily been optimizing the ratio of secondary metals, overlooking the significance of interface control for efficient CO
2RR.
In this study, we fabricated the facet-controlled Cu
2O nanocrystals (NCs) and studied the effect of bimetallic interface design on the CO
2RR. Cu
2O NCs includes cube with (100) facets, cuboctahedron (cubo) with (100) and (111) facets, and octahedron (octa) with (111) facets. We introduced Ag and Au as secondary metals to facet controlled Cu
2O NCs through galvanic replacement. Shape and size distributions of the secondary metal were affected by surface energy and the surface atomic diffusion rate. These factors proved to be pivotal in the fabrication of three distinct catalysts, each characterized by varying Cu-Ag, Cu-Au interfacial compositions. In general, Cu
2O cube with low-surface-energy exhibited segregation and agglomeration at the interfaces, whereas Cu
2O cubo and octa with high-surface-energy formed well-dispersed interfaces. Bare Cu
2O cube exhibited a 40% Faradaic efficiency (FE) for C
2+ products and achieved H
2 FE of 19% at -0.73 V (vs RHE). Ag-augmented Cu
2O cube significantly improved selectivity by reaching 57% FE for C
2+ and suppressing H
2 with a FE of 13% at -0.78 V (vs RHE). In contrast, the Au-augmented Cu
2O cube promoted H
2 with 25% FE and C
2+ with 33% FE at -0.99 V (vs RHE), resulting in reduced performance. To gain deeper insights into the intermediate behavior of *CO,
in-situ Raman spectroscopy was employed, highlighting the critical importance of the metal effect in CO
2RR. Remarkably, it was observed that CO derived from Ag had a more pronounced impact on increasing *CO coverage on the Cu surface compared to that of Au. Furthermore, the relatively higher portion of high-frequency band (HFB) *CO
atop represents efficient C-C coupling. This study sheds light on the bimetallic interface design of Cu-based active sites for efficient C
2+ chemical production in CO
2RR.