Microfluidic Continuous Synthesis of Size‐ and Facet‐Controlled Porous Bi ₂ O ₃ Nanospheres for Efficient CO ₂ to Formate Catalysis

Abstract Bismuth‐based catalysts are effective in converting carbon dioxide into formate via electrocatalysis. Precise control of the morphology, size, and facets of bismuth‐based catalysts is crucial for achieving high selectivity and activity. In this work, an efficient, large‐scale continuous production strategy is developed for achieving a porous nanospheres Bi ₂ O ₃ ‐FDCA material. First‐principles simulations conducted in advance indicate that the Bi ₂ O ₃ (111)/(200) facets help reduce the overpotential for formate production in electrocatalytic carbon dioxide reduction reaction (ECO ₂ RR). Subsequently, using microfluidic technology and molecular control to precisely adjust the amount of 2, 5‐furandicarboxylic acid, nanomaterials rich in (111)/(200) facets are successfully synthesized. Additionally, the morphology of the porous nanospheres significantly increases the adsorption capacity and active sites for carbon dioxide. These synergistic effects allow the porous Bi ₂ O ₃ ‐FDCA nanospheres to stably operate for 90 h in a flow cell at a current density of ≈250 mA cm ^{− 2} , with an average Faradaic efficiency for formate exceeding 90%. The approach of theoretically guided microfluidic technology for the large‐scale synthesis of finely structured, efficient bismuth‐based materials for ECO ₂ RR may provide valuable references for the chemical engineering of intelligent nanocatalysts.