A visible light induced ultrasensitive photoelectrochemical sensor based on Cu3Mo2O9/BaTiO3 p–n heterojunction for detecting oxytetracycline

In this paper, an ultrasensitive photoelectrochemical sensor was developed for the detection of oxytetracycline , which was based on BaTiO 3 sensitized Cu 3 Mo 2 O 9 nano-composites with excellent visible-light photoelectrochemical activity. Cu 3 Mo 2 O 9 nanocrystals (NCs) with popsicle-like morphologies were synthesized through hydrothermal method and showed a very high photoelectrochemical signal. To achieve larger photocurrent density, nanostructured BaTiO 3 was then deposited on the surface of Cu 3 Mo 2 O 9 photocathodes, which led to 3-fold enhancement of the photocurrent as compared to pristine Cu 3 Mo 2 O 9 NCs. In order to obtain the specific response to oxytetracycline, oxytetracycline aptamer was fixed on the Au/BaTiO 3 /Cu 3 Mo 2 O 9 /FTO. Under visible light irradiation , the obtained aptamer/Au/BaTiO 3 /Cu 3 Mo 2 O 9 /FTO exhibited high sensitivity, good selectivity , outstanding reproducibility and low cost for detecting oxytetracycline. Furthermore, there was a linear relationship between detected signal and the oxytetracycline in the concentration range from 5   ×   10 −10 to 10 −7   M, with a detection limit (3 S/N) of 4.6   ×   10 −11   M under the optimal conditions. It is expected that this new photoelectric active material may have potential applications in biosensors, photocatalysis and other related fields.