An ultrasensitive free-of-electronic sacrificial agent photoelectrochemical aptasensor for the detection of dibutyl phthalate based on Z-scheme p-n Bi-doped BiOI/BiS heterojunction.

Dibutyl phthalate (DBP), a common and outstanding plasticizer, exhibits estrogenic, mutagenic, carcinogenic, and teratogenic properties. It is easily liberated from plastic materials and pollutes aquatic ecosystems, endangering human health. Therefore, highly sensitive and selective DBP detection methods are necessary. In this work, a free-of-electronic sacrificial agent photoelectrochemical (PEC) aptasensor for DBP detection was constructed using a novel Z-scheme Bi-doped BiOI/BiS (Bi-BIS) p-n heterojunction. The Bi-BIS composites had higher visible-light absorption, charge transfer, and separation efficiency. This is attributed to the synergistic effect of the formation of Z-scheme p-n heterojunction between BiOI and BiS, the plasma resonance effect of metallic Bi and photosensitization of BiS, thus exhibiting large and stable photocurrent response in the absence of electron sacrificial agent, that was 10.4 and 6.4 times higher than that of BiOI and BiS, respectively. Then, a DBP PEC aptasensor was constructed by modifying the DBP aptamer on the surface of the ITO/Bi-BIS electrode. The aptasensor demonstrated a broad linear range (2-500 pM) and a low detection limit (0.184 pM). What's more, because there is no interference from electronic sacrificial agent, the aptasensor exhibited excellent selectivity in real water samples. Therefore, the proposed PEC has considerable potential for DBP monitoring.