Hierarchical Bimetallic Electrocatalyst with Amorphous SnO Layer for Highly Efficient Electroreduction of CO2

Abstract Renewable electricity‐driven reduction of CO 2 into value‐added chemicals has been recognized as a promising sustainable energy conversion method to achieve carbon‐neutrality. Although Sn‐based catalysts show excellent selectivity towards CO and HCOOH in CO 2 reduction, the reaction activity, i. e. current density, remains quite low (<100 mA cm −2 ). Herein, a hierarchical bimetallic electrocatalyst consisting of Cu foam‐supported bundle‐like structure and thin amorphous SnO layer was fabricated for efficient electroreduction of CO 2 to C1 products (CO and HCOOH). The hierarchical structure ensured higher large electrochemically active surface area, while the thin amorphous SnO layer could efficiently adsorb CO 2 , and stabilize the *CO 2 − intermediate formed in the rate‐determining step, thereby boosting the reaction activity of CO 2 reduction. As a result, an unprecedented partial current density of 128.6 mA cm −2 was achieved for C1 products at −1.4 V vs. RHE with a Faradaic efficiency of 79.2 % in an H‐type cell. The strategy of integrating optimized structure with active site here may be beneficial to other related energy conversion systems.