An ultrasensitive label-free photoelectrochemical sensor based on Ag2O-sensitized WO3/TiO2 acicular composite for AFB1 detection

Abstract

Tungsten trioxide (WO₃) nanoplates (NPs) were modified on fluorine-doped SnO₂ transparent conductive glass (FTO) electrodes by the wet chemical route, and oriented titanium dioxide (TiO₂) nanoprickles were tightly and uniformly synthesized on the surface of WO₃ by the chemical bath deposition (CBD) method to obtain the WO₃/TiO₂ composite. Thereafter, Ag₂O nanoparticles were formed on the surface of the WO₃/TiO₂ composite by an in situ growth method. With glutathione (GSH) as the electron donor and visible-light excitation, the WO₃/TiO₂/Ag₂O composite exhibited a worthwhile photoelectric signal, reaching about 56 μA. Therefore, the label-free PEC sensor was successfully prepared for the supersensitive detection of aflatoxin B1 (AFB1). When the concentration of AFB1 was within 0.005–0.4 ng mL⁻¹, the photocurrents showed a linear downward trend with a detection limit of 1.67 pg mL⁻¹. Moreover, AFB1 was satisfactory in the selectivity tests involving zearalenone (ZEN), vomitoxin (DON), and ochratoxin A (OTA). Furthermore, the PEC sensor exhibited the characteristics of stability and good reproducibility, which has broad application prospects in the detection of other toxic small molecules as well as in the preparation of a photoelectric material.