Electrocatalytic CO₂ reduction reaction (CO₂RR) is an attractive way to produce renewable fuel and chemical feedstock, especially when coupled with efficient CO₂ capture and clean energy sources. On the fundamental side, research on improving CO₂RR activity still revolves around late transition metal-based catalysts, which are limited by unfavorable scaling relations despite intense investigation. Here, we report a combined experimental and theoretical investigation into electrocatalytic CO₂RR on Ti- and Mo-based MXene catalysts. Formic acid is found as the main product on Ti₂CT_x and Mo₂CT_x MXenes, with peak Faradaic efficiency of over 56% on Ti₂CT_x and partial current density of up to −2.5 mA cm⁻² on Mo₂CT_x. Furthermore, simulations reveal the critical role of the T_x group: a smaller overpotential is found to occur at lower amounts of –F termination. This work represents an important step toward experimental demonstration of MXenes for more complex electrocatalytic reactions in the future.

电催化的CO ₂还原反应（CO ₂ RR）是生产可再生燃料和化学原料的一种有吸引力的方法，尤其是与有效的CO ₂捕获和清洁能源结合使用时。从根本上讲，提高CO ₂ RR活性的研究仍围绕着后期过渡金属基催化剂进行，尽管进行了深入研究，但仍受到不利的比例关系的限制。在这里，我们报告结合实验和理论研究的钛和钼基MXene催化剂上的电催化CO ₂ RR。发现甲酸是Ti ₂ CT _x和Mo ₂ CT _x上的主要产物MXene，在Ti ₂ CT _x上的法拉第峰值效率超过56％，在Mo ₂ CT _x上的部分电流密度高达-2.5 mA cm ^-2。此外，模拟揭示了T _x基团的关键作用：发现较小的–F端接处会出现较小的过电势。这项工作是迈向未来针对更复杂的电催化反应的MXene实验演示的重要一步。