MoS2/nitrogen doped graphene hydrogels p-n heterojunction: Efficient charge transfer property for highly sensitive and selective photoelectrochemical analysis of chloramphenicol

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 μg/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.