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

Graphical Foam supported : The hierarchical bimetallic electrocatalyst comprising Cu foam-supported bundle-like structure with thin amorphous SnO shell (Sn-24 h@CB) was successfully synthesized for highly efficient electrocatalytic reduction of carbon dioxide. An unprecedented partial current density of C1 products (CO and HCOOH) up to 128.6 mA cm −2 was achieved with a Faradaic efficiency of ∼80 % in H-type cell. 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.