Solvent‐Free Manufacturing of Multifunctional Gas Diffusion Electrode Architectures for Enhanced CO ₂ Conversion From Low‐Concentration Streams

ABSTRACT Electrochemical CO 2 reduction offers a sustainable route to convert greenhouse gases into valuable chemicals and fuels, although unsatisfactory selectivity and sluggish kinetics at low CO 2 concentrations (5–15 vol.%) have hampered its deployment. This work invents a tandem gas diffusion electrode (GDE) leveraging hierarchically engineered microgranules consisting of metal–organic‐frameworks (MOFs), carbon nanotubes (CNTs), and copper nanoparticles to spatially integrate CO 2 pre‐concentration, CO generation, and C─C coupling, significantly enhancing CO 2 ‐to‐C 2 product selectivity via closely coupled active zones. A key innovation lies in the solvent‐free manufacturing of microgranule‐loaded GDEs, which circumvents the dispersion limitations of solvent‐based methods and enables uniform, scalable integration for tandem GDEs targeting low‐concentration CO 2 reduction. The fabricated tandem GDE demonstrates an impressive 39% ± 1% Faradaic efficiency toward C 2 H 4 (FE C2H4 ) and a record high partial current density of 99 mA cm −2 (j C2H4 ) at a 15 vol.% CO 2 stream. To our knowledge, this represents the highest performance reported for low‐concentration CO 2 streams.