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.