(79c) Operando Spectroscopic Investigations of Oxide Derived Metal Catalysts for CO2 and CO Reduction

Electrochemical reduction of CO₂ driven by renewable electricity is a promising approach to convert CO₂ into valuable chemicals and fuels. Copper is the only metal catalyst for this reaction with significant selectivity towards hydrocarbons and oxygenates. CO is a known intermediate in the reduction of CO₂, and thus its conversion is also of notable interest. Oxide derived copper (OD-Cu) has been shown to favor the more desirable C2 and C3 products at lower overpotentials than bulk copper. Despite numerous studies and proposed mechanisms, e.g., the presence of grain boundaries, surface pH and surface roughness, the exact nature of the active phase is still a topic of discussion. In this work, we use operando attenuated total reflectance surface enhanced infrared reflection absorption spectroscopy (ATR-SEIRAS) to probe different types of sites available on Cu and OD-Cu surfaces using CO as a probe molecule. We show that multiple types of CO-binding sites are available on both Cu and OD-Cu surfaces. Further, the types of binding sites present are also strongly potential dependent. We identify strong correlations between the presence of several types of surface sites with the ability of the catalyst to produce C2 and C3 products at -0.4 V vs. RHE.