Controlled boron incorporation tuned two-phase interfaces and Lewis acid sites in bismuth nanosheets for driving CO2 electroreduction to formate

Rationally designing advanced electrocatalysts and innovative energy-efficient electrolysis systems for converting carbon dioxide (CO2) into value-added chemicals or fuels is of significance yet challenging. As for the electrochemical CO2 reduction reaction (CO2RR), the electrocatalytic efficiency is largely limited by the CO2 adsorption and activation capability of active sites. Herein, B-doped Bi nanosheet arrays grown on Cu foam are synthesized by a galvanic replacement combined with in situ doping strategy. It was demonstrated that the B dopant could serve as Lewis acid sites for promoting the adsorption of CO2, and more importantly, regulate the electronic structure and crystallinity of Bi nanosheet arrays, and create abundant amorphous/crystalline two-phase interfaces, which boost the CO2RR activity. Moreover, coupling the CO2RR with the thermodynamically more favorable methanol oxidation reaction (replacing the kinetically sluggish oxygen evolution reaction) within a pH-asymmetric electrolysis system could realize highly efficient pair-electrosynthesis of formate with a much-reduced energy consumption compared with a conventional electrochemical CO2RR system.