In situ study of surface species and structure over Oxide-Derived Copper Catalysts for Electrochemical CO2 Reduction

Abstract

The oxide-derived copper (OD-Cu) has been discovered as effective catalyst for electroreduction of CO2 to C2+ products. The real structure of the OD-Cu and surface species in the reaction process are interesting phenomena, which are not clear now. Herein, in situ surface-enhanced Raman spectroscopy (SERS), operando X-ray absorption spectroscopy (XAS), 18O isotope labeling experiments, and density functional theory were employed to investigate the surface speciation and structure of the OD-Cu catalysts during CO2 electroreduction. It was found that the OD-Cu catalysts were reduced to metallic Cu(0) in the reaction. CuOx species existed on the catalyst surfaces during CO2RR, which resulted from the chemisorption of CO2 instead of active sites of the catalyst. After removing potential, Cu2O was formed on the surface of the catalyst by reaction of Cu and H2O. It was also found that Cu (100) facet can be enhanced by redox cycling treatment of the catalyst, leading to outstanding performance of the catalyst. The Faradaic efficiency(FE) for C2+ products reached up to 83.8% at current density of 341.5 mA•cm-2 at -0.9 V vs RHE. The findings of this work are very interesting knowledge in the area in electrochemical reduction of CO2. The work also demonstrates advantage and necessity of in situ experimental methods in exploring the interesting phenomena in the process of CO2RR.

Spatiotemporal Mapping of Local Heterogeneities during Electrochemical Carbon Dioxide Reduction

“…33,36−41 For this purpose, in situ and operando characterization techniques play an important role. 42 A lot of research has been conducted using analytical techniques with different spatial and temporal resolution, such as atomic force microscopy, 43 attenuated total reflection infrared spectroscopy (ATR−IR), 31,32,44 surface-enhanced Raman spectroscopy (SERS), 36,45−47 scanning electrochemical microscopy, 5,33 and synchrotron-based X-ray methods, 27,28 details of the eCO 2 RR and the restructuring of the copper surface under reaction conditions. However, many of the in situ and operando experiments still lack the combination of both temporal and spatial spectroscopic information to reveal reaction dynamics and heterogeneities on relevant space-and time-scales for the eCO 2 RR.…”