A novel signal-on photoelectrochemical platform for highly sensitive detection of alkaline phosphatase based on dual Z-scheme CdS/Bi2S3/BiOCl composites

This work proposes a dual Z-scheme photoelectronic material for amplifying photoelectrochemical (PEC) biosensing signal. Herein, CdS/Bi2S3/BiOCl with great PEC performance is obtained by one-step synthesis strategy for the first time. Thereinto, the unique dual Z-scheme material displays higher activity compared with a single material and binary composites. In addition, l-ascorbic acid 2-phosphate is catalyzed in situ by alkaline phosphatase (ALP) to produce ascorbic acid (electron donor). The cross-linking reaction of chitosan and glutaraldehyde is applied for fixing ALP. Since the electron donor is produced by the catalytic reaction, the recombination of photo-induced electrons and holes is inhibited. Accordingly, the photocurrent is increased, getting the phenomenon of signal-on. Under optimal conditions, the sensing platform is constructed in a desired linear range (0.1–4000 U L−1) as well as the detection limit of 0.06 U L−1. The established PEC platform shows good stability and specificity. Consequently, Z-scheme CdS/Bi2S3/BiOCl would provide a potential strategy for PEC analysis and the field of photocatalysis.