Ternary Z-scheme heterojunction of Bi SPR-promoted BiVO/g-CN with effectively boosted photoelectrochemical activity for constructing oxytetracycline aptasensor.

Developing photoactive materials with wide spectral response is critical to improve the sensitivity of PEC biosensors. Herein, a sensitive photoelectrochemical (PEC) aptasensor was fabricated based on Bi surface plasmon resonance (SPR)-promoted BiVO/g-CN (Bi/BiVO/g-CN) as photoactive material for the detection of oxytetracycline (OTC). Ternary Z-scheme Bi/BiVO/g-CN heterojunction exhibited widest spectral response and best PEC activity compared to g-CN, BiVO, Bi/BiVO, and BiVO/g-CN. The wide spectral response and high PEC activity could be attributed to three reasons: Firstly, the SPR effect of Bi could greatly increase light harvesting; Secondly, Bi served as an electron conduction bridge between BiVO and g-CN to form Z-scheme structure, significantly accelerating the separation of photogenerated carriers; Thirdly, the synergism of Z-scheme heterojunction and the SPR effect of Bi efficiently boosted the photoelectric response. Based on the above sensitization strategies, the proposed PEC aptasensor for OTC determination showed a wide linear range of 0.01-1000 nM and a low detection limit (S/N = 3) of 3.3 × 10 nM. Moreover, the high stability, satisfactory repeatability and favorable practicability of the fabricated PEC aptasensor revealed the potential applications for accurate monitoring of antibiotics in environmental media.