Controlling Speciation during CO2 Reduction on Cu-Alloy Electrodes

• Published in: ACS catalysis 2020-01, Vol.10 (1), p.672-682
• Main Authors: Chen, Xinyi, Henckel, Danielle A, Nwabara, Uzoma O, Li, Yuanyuan, Frenkel, Anatoly I, Fister, Tim T, Kenis, Paul J. A, Gewirth, Andrew A
• Format: Article
• Language: English
• ISSN: 2155-5435; 2155-5435
• DOI: 10.1021/acscatal.9b04368

Electrodeposition of Cu, Cu/Ag, and Cu/Sn alloy films by using 3,5-diamino-1,2,4-triazole (DAT) as an electrodeposition inhibitor yields a high surface area Cu-based catalyst. All three Cu-based electrodes exhibit high Faradaic efficiency (FE) of CO2 reduction toward C2H4 production. The CuSn-DAT electrode exhibits the highest FE for CO (∼90% at −0.4 V) and C2H4 (∼60% at −0.8 V) production and high current density (∼−225 mA/cm2 at −0.8 V). In situ surface enhanced Raman spectroscopy (SERS) studies in a flow cell obtained from the three Cu-based samples show a correlation between the decreased oxide content on the Cu surface, increased presence of CO, and increased activity for CO and C2 production. The CuSn-DAT electrode has the lowest amount of Cu2O and exhibits the highest activity, whereas the Cu-DAT electrode has an increasing Cu2O content and exhibits lower activity as the potential is made negative. These results demonstrate that incorporation of different well-mixed alloy materials provides a way to tune CO2 reduction speciation.