Bi2O3/MgIn2S4 type-II heterojunction-driven photoelectrochemical sensor for selective detection of tert-butylhydroquinone in edible oils

Tert-butylhydroquinone (TBHQ) is a common antioxidant in food oils, and reliable detection methods are needed to ensure food safety. Here, a photoelectrochemical (PEC) sensor based on Bi 2 O 3 /MgIn 2 S 4 /GCE was developed for the detection of TBHQ. The sensor performance was significantly enhanced through electrostatic assembly of sheet-like Bi 2 O 3 onto flower-like MgIn 2 S 4 , forming a type-II heterojunction with carefully controlled component ratios, pH, and applied potential. The improved detection capability is attributed to the synergistic effect of the heterojunction structure. Furthermore, the selectivity of the sensor towards TBHQ was elucidated through the study of electrostatic interactions and redox potentials. The detection limit of the developed Bi 2 O 3 /MgIn 2 S 4 /GCE sensor was as low as 9 nM with two linear ranges (0.03–0.18 μM and 0.18–60 μM). Its effectiveness in monitoring food safety has been demonstrated by successful uses in blend oils and soybean oils.