In-situ growth of flower-like CdIn2S4 on three-dimensional microspheres SnIn4S8 to form S-scheme heterojunction for efficient detection of tert-butylhydroquinone in edible oils

• A low-cost and simple method for the determination of TBHQ in edible oils. • Analysis of TBHQ detection using redox potential and electrostatic potential. • The sensor was verified to be composed of S-scheme heterostructures by DFT. • The constructed PEC sensor has ultra-low LOD and ultra-wide linear range. • The properties of CdIn 2 S 4 /SnIn 4 S 8 show a pattern as the ratio of CdIn 2 S 4 increases. As an oil-soluble antioxidant, tert -butylhydroquinone (TBHQ) is widely used in edible oils, so accurate control of its content is significant for food safety. Here, a CdIn 2 S 4 /SnIn 4 S 8 S-scheme heterojunction structure was constructed by in-situ growth of smooth flower-like CdIn 2 S 4 on rough three-dimensional SnIn 4 S 8 microspheres via a one-pot co-precipitation technique. Subsequently, TBHQ was combined with CdIn 2 S 4 /SnIn 4 S 8 /GCE, and the photocurrent signal was significantly increased, which could be detected in the concentration range from 0.02 to 150 μM, with the limit of detection as low as 2 nM. The reaction mechanism of CdIn 2 S 4 /SnIn 4 S 8 composites was verified by using density functional theory calculations. Meanwhile, the reason for the outstanding detection of TBHQ was investigated by exploring the electrostatic potential and the related redox potential. In addition, the sensor was demonstrated to have excellent recoveries by comparing UV–Vis spectrophotometry for the detection of TBHQ in peanut oil, canola oil, blended oil, and soybean oil.