As a promising ammonia synthesis approach to replace the industrial Harber method, the biggest problem restricting photocatalytic nitrogen fixation is the suboptimal efficiency. Herein, novel surface oxygen vacancies modified micro-nanosheet structure Bi2O2CO3 (namely BOC/OV) were successfully synthesized via facile formation under room temperature. These defects-rich nanosheets exhibit outstanding performance for photocatalytic nitrogen fixation under visible light. The surface oxygen vacancies provide abundant active sites for molecular N-2 activation, and the effect of scattered nanometer-size could facilitate the separation of photo-generated charges. Moreover, the energy band can be consecutively tuned with the accumulation of surface oxygen vacancies by lowering the conduction band position. Among all as-prepared samples, BOC/OV3 exhibited the highest NH4+ yield, reaching 1178 mu mol.L-1.g(-1).h(-1), which is 10 times than that of pristine Bi2O2CO3. In this work, all samples synthesis and defects formation were conducted without requiring any secondary energy, which is of great significance for realizing green and efficient artificial ammonia synthesis. (c) 2020 Elsevier Inc. All rights reserved.