Tuning flow-through cu-based hollow fiber gas-diffusion electrode for high-efficiency carbon monoxide (CO) electroreduction to C₂₊products

Electrochemical carbon monoxide reduction (CORR) to C2+ products has advantages over electrochemical CO2 conversion (CO2RR) as issues such as carbonation, and CO2 loss during CO2RR are omitted in CORR due to the stability of CO in alkaline solutions. Facing common challenges as CO2RR, CORR suffers more from mass transport resistance and intrinsically lower aqueous CO solubility. Therefore gas-diffusion electrodes (GDEs) are desired to boost the formation of triple phases and active sites to obtain higher reaction rates. Herein, for the first time Cu-based hollow fiber GDEs (HFGDEs) are tuned for CORR to C2+ products. By growing a layer of Cu nanocubes as the catalyst layer on HFGDEs, non-selective pristine copper HFGDE became highly selective for C2+ products (FE>90%), with ethylene as the main product (FE>65%), owing to the dominant Cu (100) facet in Cu nanocubes with high C2+ selectivity. In addition, ultra-high ethylene partial current density of > 470 mA cm(-2) at -0.8 V vs. RHE in 5.0 M KOH was obtained, owing to the abundant porosity and surface area available for triple-phase formation on microtubular GDEs and their enhanced mass transport. The electrodes exhibited one of the highest partial current densities achieved for ethylene production, indicating the promises of flow-through hollow fiber configuration for other desired products or gas-phase electrochemical reactions with low aqueous solubility.