Well-matched dual photoelectrodes regulated cathodic photoelectrochemical aptasensing capability: Elucidating the role of photoanode in enhancing the sensing signal

To screen well-matched photoelectrodes is highly desirable for achieving efficient signal amplification of the dual-photoelectrode photoelectrochemical (PEC) system. However, the role of photoanode in the characteristic signal amplification remains unclear. In this study, an integrated PEC system was developed by employing well-matched ZnIn 2 S 4 /Bi 2 S 3 photoanode and BiOBr-Au nanoparticles (NPs) photocathode . ZnIn 2 S 4 /Bi 2 S 3 with super light-harvesting property and Z-scheme electron transfer pathway, served as the photoanode to continuously inject electrons into the photocathode under visible light , resulted in a 69 times enhanced photocurrent signal than that of conventional PEC system. More importantly, a systematic discussion of photoanode in enhancing the sensing signal was presented through the experimental measurements of Mott-Schottky and open-circuit voltage. Using ofloxacin (OFL) as a model target, an aptasensor was constructed for its potential sensing applications, and the possible reaction mechanism of OFL were also conducted. The proposed aptasensor demonstrated the capability to detect concentrations of OFL ranging from 0.1 pM to 5 nM, achieving a detection limit of 47 fM ( S/N = 3). Moreover, the aptasensing platform exhibited advantages of high sensitivity, good anti-interference and repeatability. This study proposed insights in understanding the role of photoanode for designing more efficient dual-photoelectrode PEC aptasensors for precise monitoring of other environmental pollutants . • A novel ZnIn 2 S 4 /Bi 2 S 3 photoanode with super light-harvesting ability was prepared. • An integrated PEC system was developed based on well-matched photoelectrodes. • Primary factors affecting the signal amplification of the PEC system were explored. • The proposed aptasensor merits the advantages for OFL detection in water samples.