Enhanced Label-Free Photoelectrochemical Strategy for Pollutant Detection: Using Surface Oxygen Vacancies-Enriched BiVO₄ Photoanode

Abstract

Label-free photoelectrochemical sensors have the advantages of high sensitivity and a simple electrode structure. However, its performance is greatly limited due to the photoactive materials’ weak photoactivity and poor stability. Herein, a robust homogeneous photoelectrochemical (PEC) aptasensor has been constructed for atrazine (ATZ) based on photoetching (PE) surface oxygen vacancies (O v )-enriched Bismuth vanadate (BiVO 4 ) (PE-BVO). The surface of the O v improves the carrier separation ability of BiVO 4, thus providing a superior signal substrate for the sensor. A thiol molecular layer self-assembled on PE-BVO acts as a blocker, while 2D graphene acts as a signal-on probe after release from the aptamer–graphene complex. The fabricated sensor has a wide linear detection range of 0.5 pM to 10.0 nM and a low detection limit of 0.34 pM (S/N = 3) for ATZ. In addition, it can efficiently work in a wide pH range (3–13) and high ionic strength (∼6 M Na + ), which provides promising opportunities for detecting environmental pollutants under complex conditions.