Enhancing the photoelectric performance of TiO2-based heterojunction using the hydrothermal decomposition of MIL-125 strategy for sensitive detection of Bisphenol A

Due to its outstanding conductive properties, TiO2-based heterojunctions have extensive applications in the field of photoelectrochemical sensors. However, due to surface energy and van der Waals forces, TiO2 tends to aggregate and presents an uneven distribution, which reduces the overall performance of these heterostructures. To overcome these challenges and achieve a uniform distribution of TiO2 within the heterojunction, the characteristic of gradual decomposition of the metal-organic framework MIL-125 under hydrothermal conditions was employed. This process gradually generates TiO2 particles that slowly participate in the construction of the heterojunction. By combining the exceptional light absorption properties and appropriate bandgap widths of CdS and CdIn2S4, a uniformly distributed flower-globular ternary heterojunction CdS/CdIn2S4/TiO2-FG was successfully synthesized. In comparison to the disordered heterojunction CdS/CdIn2S4/TiO2-DO, CdS/CdIn2S4/TiO2-FG exhibits enhanced visible light absorption properties and photoelectric conversion efficiency. Taking Bisphenol A (BPA) as a model, a signal-off photoelectrochemical (PEC) aptasensor based on the CdS/CdIn2S4/TiO2-FG was established and exhibited a high sensitive detection for BPA with a linear response range from 10-1 to 107 pM, as well as an ultralow detection limit of 0.015 pM, revealing vivid selectivity, stability, and reproducibility. Therefore, this study offers an efficient and straightforward approach for the preparation of TiO2-based heterojunctions with superior photoelectric activity.