Enhanced Label-Free\nPhotoelectrochemical Strategy\nfor Pollutant Detection: Using Surface Oxygen Vacancies-Enriched BiVO₄ Photoanode

Abstract

Label-free photoelectrochemical sensors have the advantages\nof\nhigh sensitivity and a simple electrode structure. However, its performance\nis greatly limited due to the photoactive materials’ weak photoactivity\nand poor stability. Herein, a robust homogeneous photoelectrochemical\n(PEC) aptasensor has been constructed for atrazine (ATZ) based on\nphotoetching (PE) surface oxygen vacancies (O_v)-enriched\nBismuth vanadate (BiVO₄) (PE-BVO). The surface of the O_v improves the carrier separation ability of BiVO₄, thus providing a superior signal substrate for the sensor. A thiol\nmolecular layer self-assembled on PE-BVO acts as a blocker, while\n2D graphene acts as a signal-on probe after release from the aptamer–graphene\ncomplex. The fabricated sensor has a wide linear detection range of\n0.5 pM to 10.0 nM and a low detection limit of 0.34 pM (S/N = 3) for\nATZ. In addition, it can efficiently work in a wide pH range (3–13)\nand high ionic strength (∼6 M Na⁺), which provides\npromising opportunities for detecting environmental pollutants under\ncomplex conditions.