Visible light-activated self-powered photoelectrochemical aptasensor for ultrasensitive chloramphenicol detection based on DFT-proved Z-scheme Ag2CrO4/g-C3N4/graphene oxide.

A visible light self-powered photoelectrochemical (PEC) aptasensor based on silver chromate particles, graphitic carbon nitride nanosheets and graphene oxide sheets (Ag2CrO4/g-C3N4/GO) for the ultrasensitive detection of chloramphenicol (CAP) was reported in this work. g-C3N4 was considered to be the fundamental photoelectric material because of its great oxidation ability of photogenerated hole as well as excellent biocompatibility and low toxicity. However, the narrow light absorption range and rapid carrier recombination rate limit the application of pure g-C3N4. Herein, Ag2CrO4 and GO as photosensitizer were introduced to improve the photoelectric properties of g-C3N4. The photocurrent of the developed ternary composite was about 3 times higher than that of pristine g-C3N4, which proves it can be used as a suitable photoelectric active material. Moreover, the mechanism of Z-scheme electron transfer path was proved by density functional theory (DFT) calculation. The fabricated PEC aptasensor exhibited high sensitivity toward CAP with a wide liner response of 0.5 pM to 50 nM and a detection limit of 0.29 pM. The specific recognition mechanism and excellent sensing performance indicated this aptasensor could serve as a useful tool for selective and ultrasensitive CAP detection in practical analysis.