Thermal Driven High Crystallinity of Bismuth as Robust Catalyst for CO2 Electroreduction to Formate

Abstract Electrochemical reduction of carbon dioxide (CO 2 ) can convert greenhouse gases into high value‐added carbon‐based fuels and chemicals, providing a sustainable way to solve energy and environmental crises. Bismuth based catalysts have been found with excellent performance towards CO 2 electroreduction to formate but facing great challenge in exploring simple synthesis methods. Herein, the bismuth nanospheres (Bi NSs) with controlled crystallinity were synthesized through a facile solvothermal method following by annealing treatment under Argon protection. For the first time, we demonstrate the catalytic performance of Bi NSs was closely related to the crystallinity. High crystallinity endows Bi NSs with more distinct grain boundaries, providing more active sites for CO 2 electroreduction. In a broad potential range from −1.0 to −1.4 V vs . reversible hydrogen electrode (RHE), a high faradaic efficiency of 91∼95 % towards formate was achieved on the high crystallinity Bi NSs.