▎ 摘　　要

In this study, the graphene sheets embedded carbon (GSEC) film was modified with surface N-doping for highly selective ascorbic acid (AA) sensing. We found that the N-doped graphene sheets formed in-situ at the carbon film surface and induced high electrocatalytic activity for AA oxidation. Although surface N-doping slightly decreased the I-D/I-G and surface roughness of carbon film, the graphene sheets embedded in amorphous were preserved. With surface N-doping, the charge-transfer resistance was reduced from 22.5 Omega cm(2) to 3.9 Omega cm(2), the oxidation-reduction peak separation decreased to a low value of 65.7 mV in Fe(CN)(6)(4-/3-) redox system, and the standard rate constant was increased from 0.24 x 10(-2) to 1.36 x 10(-2) cm.s(-1). The surface N-doped graphene sheets embedded carbon (SN-GSEC) decreased the oxidation potential of AA from 0.186 V to 0.025 V (vs. Ag/AgCl) and realized selective detecting of AA. The mechanism may be that the surface N-doping induce the adjacent carbon in graphene sheets to obtain a higher partial density of states and more positive compensating charge. This study provides a simple method for preparing high performance electrochemical biosensor.