▎ 摘　　要

Constructing junctions between semiconductors is an effective way to promote charge separation and thus to improve the photoelectrochemical (PEC) performances, and specifically, p-n heterojunction is considered as a very promising structure. Herein, we designed and fabricated MoS2/nitrogen doped graphene hydrogels (MoS2/NGH) p-n heterojunction by a facile one-pot hydrothermal route. The as-fabricaterd MoS2/NGH heterostructures demonstrated the excellent PEC activity, exhibiting enhanced photocurrent intensity by the fast transfer and separation rate of photogenerated electron-hole owing to the construction of p-n heterojunction. Based on the high PEC performances of the MoS2/NGH heterostructure, a novel sensitive PEC sensor was developed for the determination of chloramphenicol (CAP) with the assistance of aptamer. In the presence of target molecules, the as-fabricated PEC sensor could recognize the CAP quickly and then consume the holes in the interface of heterostructures, inhibiting the recombination of photogenerated electron-hole pairs, resulting the enhanced photocurrent. Specially, with the concentration of CAP increased, the photocurrent enhanced gradually. Excellent linearity was obtained in the concentration range from 32.3 ng/L to 96.9 mu g/L, and the limit of detection was 3.23 ng/L. Moreover, the as-fabricated PEC sensor exhibited rapid response, high stability, low-cost and high selectivity, which could be successfully applied to the analysis of CAP in honeycomb samples.