▎ 摘　　要

Nitrogen-doped graphene (NG) materials were prepared with different levels of ammonia modification and their capacitive performances were compared. The surface structure, nitrogen species and contents, as well as the defects and disorders of the as-prepared NG materials were investigated. Electrochemical measurements showed that the capacitance of the NG materials is significantly higher than that of pristine graphene and varies with the ammonia dosage. Graphene modified with 20 mL of ammonia possesses the highest capacitance among all of the materials studied. Further investigation showed that nitrogen species and defects in NG perform pivotal functions in improving capacitance; by contrast, the surface morphology had little influence on the capacitance of the as-prepared NG materials. Results suggested that adjusting the N1 pyridinic N content is an efficient method for elevating the capacitive performance of NG materials.