Microfluidic continuous synthesis of size-tunable CAU-17 for efficient electrocatalytic CO2 reduction

Abstract

Bismuth-based metal–organic frameworks (MOFs) have shown promise in the electrocatalytic CO₂ reduction reaction (ECO₂RR) due to their abundant active sites and high selectivity. In this study, microfluidic synthesis technology was innovatively introduced to achieve the continuous synthesis of the bismuth-based MOF material CAU-17. Compared with the hydrothermal method, by adjusting the flow rate while keeping the temperature and Bi³⁺ reaction concentration constant, the particle size and morphology could be effectively controlled, and the synthesis time was reduced to 1/36 of that of the traditional method. CAU-17 particles with different sizes showed different reactivity sensitivities to the ECO₂RR. CAU-17-F₆₀ with the smallest particle size showed the highest Faraday efficiency of 92.79% for formate at −1.2 V_RHE, along with a larger electrochemically active surface area and lower interfacial resistance. It could be electrolyzed stably for 12 h, during which the average FE_formate remained above 90% all the time. This study thoroughly demonstrates the significant potential of microfluidic technology in the precise control of fine structures and performance optimization of MOF catalysts, offering a new idea and a generalizable path for the sustainable preparation of efficient ECO₂RR catalysts.