Gas penetrating hollow fiber Bi with contractive bond enables industry-level CO2 electroreduction

Electrochemical conversion of carbon dioxide (CO2) to valuable fuels driven by renewable electricity exhibits significant potential for achieving carbon neutrality. Bismuth (Bi) possesses the reliable capability of electrocatalyzing CO2 to formate, and high formate faradaic efficiencies have been realized over Bi-based catalysts, but industry-level large current densities with high conversion rates at mild conditions remain challenging yet. Herein we present a bismuth hollow fiber (Bi HF) as a gas penetration electrode (GPE) that efficiently reduces CO2 with a formate faradaic efficiency of 93% and a current density of 1.13 A cm-2 at -1.26 V (vs. RHE), corresponding to a CO2 conversion rate of 37% under ambient temperature and pressure. Finite element analysis (FEA) and density functional theory (DFT) demonstrate that the synergetic combination of unlimited CO2 feeding to triphasic interface reactions and selective reduction induced by contractive Bi-Bi bond is responsible for the superior activity of Bi HF.