Enhanced photoelectrochemical sensing based on novel synthesized Bi2S3@Bi2O3 nanosheet heterostructure for ultrasensitive determination of L-cysteine.

The design of a low-cost and highly efficient photoactive heterojunction material for sensing is still a challenging issue. On the basis of the formation of sheet-like Bi2O3 via coating Bi2S3, a novel Bi2O3@Bi2S3 heterostructure is controllably synthesized via a facile water bath approach. The prepared Bi2O3@Bi2S3 nanosheets show a superior photoelectrochemical (PEC) performance for the detection of L-cysteine (L-Cys), and the photocurrent signal is three and four times higher than those of Bi2S3 and Bi2O3 under visible irradiation, respectively. Also, the heterostructure presents an outstanding linear range for the detection of L-Cys: 0.1-10,000 μM. In addition, the mechanism of improved PEC response of Bi2O3@Bi2S3 nanosheets is investigated according to the estimated energy band positions. Thus, the integration of the novel heterostructure and the photoelectrochemical technique demonstrates a rapid photocurrent response, showing a great effect on the performance of the sensing system and a new PEC method for highly selective and sensitive chemical detection. Graphical abstract.