In Situ Bismuth Nanosheet Assembly for Highly Selective Electrocatalytic CO2 Reduction to Formate

The reduction of carbon dioxide (CO2 ) into value-added fuels using an electrochemical method has been regarded as a compelling sustainable energy conversion technology. However, high-performance electrocatalysts for CO2 reduction reaction (CO2 RR) with high formate selectivity and good stability need to be improved. Earth-abundant Bi has been demonstrated to be active for CO2 RR to formate. Herein, we fabricated an extremely active and selective bismuth nanosheet (Bi-NSs) assembly via an in situ electrochemical transformation of (BiO)2 CO3 nanostructures. The as-prepared material exhibits high activity and selectivity for CO2 RR to formate, with nearly 94% faradaic efficiency at -1.03 V (versus reversible hydrogen electrode (vs. RHE)) and stable selectivity (>90%) in a large potential window ranging from -0.83 to -1.18 V (vs. RHE) and excellent durability during 12 h continuous electrolysis. In addition, the Bi-NSs based CO2 RR/methanol oxidation reaction (CO2 RR/MOR) electrolytic system for overall CO2 splitting was constructed, evidencing the feasibility of its practical implementation.