Catechol exerts anin situsurface oxygen vacancy effect on BiOI: an innovative signal transduction mode for cathodic photoelectrochemistry

Cathodic photoelectrochemistry, a research hotspot in state-of-art bioassays, is generally circumscribed by its monotonous signal transduction tactic of photoinduced electron transfer (PET) mechanism, which significantly narrows the scope of its applications. In this study, we reveal the surface oxygen vacancy (V_O) formation elicited by the spontaneous coordination of catechol (CA) onto the surface of BiOI nanoplates for the innovative operation of the cathodic PEC signal transduction tactic. The in situ-generated V_O functions as a carrier separation center to efficiently promote photocurrent generation. Taking tyrosinase (TYR) and Escherichia coli O157:H7 (E. coli O157:H7) as model targets, the established signal transduction tactic was validated as efficient and sensitive for the detection of the two targets with linear ranges from 1.0 × 10^-4 to 1.0 U mL^-1 and 5.0 to 1.0 × 10⁶ CFU mL^-1, respectively. Low-detection limits of 1.0 × 10^-4 U mL^-1 and 3.0 CFU mL^-1 were achieved for TYR and E. coli O157:H7, respectively. This study opens up a new perspective of in situ generated surface V_O on semiconductors, which underlies an innovative PEC signal transduction mechanism with convincing analytical performance. Hopefully, it might encourage more explorations of new methodologies for introducing surface vacancies with exquisite applications.