Efficient Electrocatalytic CO₂ Reduction to Formate via Continuous Microfluidic Synthesis of Bi₂O₃/MXene‐Based Composite Catalysts with Tunable Metal Oxide Interfaces

Abstract The large‐scale applications of electrocatalytic CO 2 reduction face numerous challenges, including suppressed HER, high catalyst costs, limited production scalability, and complex synthesis processes. Combining carbon materials with bismuth‐based catalysts is an effective strategy to enhance catalytic activity at low cost. This study utilized microfluidic technology to achieve mass aggregations of Bi 2 O 3 nanoparticles with specific surfaces and controllable size on 2D Mxene using 2, 5‐FDCA as a ligand. The In‐depth understanding of theoretical simulations indicates the MXene substrate significantly improved the catalyst's electrochemical surface area and electron transport efficiency, facilitating electrolyte penetration and reactant diffusion. While Bi 2 O 3 support provided abundant active sites for reactions. Beyond, the composite M‐Bi 2 O 3 /MXene‐400 effectively suppress HER through synergistic effects. The interaction between Bi 2 O 3 and substrate is greatly increased to stabilize the M‐Bi 2 O 3 /MXene‐400 structure under work. In a membrane electrode assembly (MEA), it operate continuously for 60 h at a cell potential of −2.8 V, achieving a current density of −300 mA cm −2 and an average Faradaic efficiency for formate exceeding 90%. This work offers new strategies for the efficient design and controllable construction of MXene‐supported nanoparticle catalysts and mass production via microfluidic technology.