Bismuth oxide nanoflakes grown on defective microporous carbon endows high-efficient CO reduction at ampere level.

Carbon dioxide electroreduction is a green technology for artificial carbon sequestration, which is being delayed from industrialization due to the lack of efficient catalysts at high current conditions. Herein, the BiO nanoflakes were uniformly grown on a defective porous carbon (PC). This self-assembling BiO/PC catalyst was applied to drive CO electroreduction at 1.0 A, 1.5 A and 2.0 A while the Faradaic efficiency of formate reaches 91.50 %, 86.30 % and 84.22 %, respectively. Density functional theory calculations revealed the intrinsic defect of carbon is able to give electron to Bi through O bridge, which increased the electron aggregation of Bi and lowered the generation energy barrier of *OCHO intermediate. Additionally, the unique 3D network of staggered BiO enhances the CO adsorption and favors the electron transportation. By integrating all above advantages into a solid electrolyte-type cell, we are able to produce pure formic acid in a rate of 15.48 mmol h at ampere current.