Porous Metallic Bismuth Micron Rods In Situ Reconstructed in a Solid-State Electrolyte MEA Electrolyzer for Efficient and Stable CO₂ Electroreduction to Formic Acid

The CO 2 electrocatalytic reduction (CO 2 RR) technique, powered by green electricity, provides an elegant way to achieve a carbon-neutral society. Here we report a porous metallic bismuth micron rod catalyst prepared by in situ reconstruction of bismuth oxide micron rods in a solid-state electrolyte membrane electrode assembly electrolyzer. We demonstrate continuous electrochemical CO 2 reduction for formic acid production at an industrial-level current density (i.e., 100 mA cm –2 ) for 70 h using porous metallic bismuth micron-rod catalysts. The Faradaic efficiency and single-pass CO 2 conversion reached 93% and 28.2%, respectively. Theoretical analysis demonstrates that the lower potential of zero charge (PZC) of the in situ reconstructed unique porous structure facilitates faster interfacial electron transfer and mass transport of CO 2 molecules. Moreover, the porous structure facilitates the adsorption of CO 2 •– and *OCHO intermediates, thereby significantly enhancing the performance of electrocatalytic reduction of CO 2 to formic acid.