In Situ Confined Growth of Bismuth Nanoribbons with Active and Robust Edge Sites for Boosted CO₂ Electroreduction

Metallic bismuth (Bi) shows great promise in electrocatalytic CO2 reduction into formate. However, the direct synthesis of active and stable Bi electrocatalysts remains a grand challenge. Herein, we present an in-plane confined hydrogen-reduction strategy for in situ growth of edge-modified Bi nanoribbons, which enables enhanced and stable reduction of CO2 into formate. Density functional theory calculations suggest that the synergistic effect of a preferentially exposed (113) facet and abundant Bi–O edge sites can contribute to a reduced formation energy for the formate intermediate. Moreover, in situ Raman characterizations reveal the Bi–O edge sites can remain stable during the reaction. Consequently, the Bi nanoribbons exhibit a high formate Faradaic efficiency of over 95% in a wide potential window. More impressively, a negligible degradation in selectivity and activity after more than 100 h of continuous operation can be achieved. This work provides a feasible strategy for fabricating robust catalysts for efficient CO2 reduction.