Bridging In Situ Measurements and Practical Conditions through Gas-Liquid Management for CO/CO2 Reduction

Abstract

Electrochemical CO₂ and CO reduction reaction (CO₍₂₎RR) has attracted growing interest for sustainable carbon conversion. Characterizing catalyst dynamics and reaction intermediates under operating conditions is important, but gas-electrolyte dynamics make in situ measurements more challenging and can complicate mechanistic interpretation. This review starts from electrochemical cell configuration and classifies them by gas-liquid configuration, including H‑type cells, flow cells, and membrane-electrode assemblies (MEA) devices that represent no gas-liquid separation, gas-liquid separation, and membrane‑confined reaction, respectively. We then summarize representative in situ cell designs under this classification and discuss their applications across different characterization techniques, as well as how the gas-liquid environment affects the observed results and mechanistic interpretation. Finally, we provide perspectives on bridging the gap between in situ characterization and practical device conditions to establish reliable structure-activity relationships in future CO₍₂₎RR studies.