Revealing Mechanistic Insights into Electrochemical CO ₂ Reduction via In Situ Fourier‐Transform Infrared Spectroscopy: Recent Advances and Perspectives on Future In Situ Designs

The electrochemical conversion of CO ₂ into valuable chemical fuels offers a promising approach to addressing environmental and energy challenges. However, catalysts used in the electrochemical CO ₂ reduction reaction (eCO ₂ RR) often undergo structural evolution under operational conditions, leading to uncertainties regarding active sites and reaction mechanisms. Real‐time monitoring of catalytic surfaces and intermediates is therefore crucial. Among various characterization techniques, in situ Fourier‐transform infrared spectroscopy (FTIR) provides unique molecular‐level insights into surface‐bound species, reaction pathways, and catalyst‐electrolyte interactions. This review highlights recent advancements in in situ FTIR applications for eCO ₂ RR, emphasizing its role in identifying active sites, materials interfaces, and transient intermediates. Additionally, methodological challenges are discussed, particularly the need for continuous‐flow electrolyzers for in situ studies, and outline future research directions to improve real‐time catalyst monitoring, advance mechanistic understanding, and enhance industrial scalability.