A novel g-C3N4/TiO2 heterojunction for ultrasensitive detection of bisphenol A residues

Semiconductor heterojunction with functional integration can be used as an excellent matrix for the ultrasensitive detection of bisphenol A (BPA) with low molecular affinity. Here, a simple, low-cost and sensitive surface-enhanced Raman scattering (SERS) strategy using g-C₃N₄/TiO₂ heterojunction as substrate was presented for detection of BPA residues in foods. The g-C₃N₄/TiO₂ achieved specific chemisorption for target analyte by the formation of intermolecular H-bond between g-C₃N₄ and BPA. And, a high-efficiency carrier separation in TiO₂ induced by heterostructure could be achieved for charge transfer between the substrate and molecule by a “donor-bridge-acceptor” charge-transfer mode. Due to the synergistic/collaborative contributions of two monomers in heterojunction, the SERS enhancement factor was as high as 3.77 × 10⁷. The detection limit of BPA residues in foods (milk, juice and drinking water) was as low as 10⁻⁹ mol·L⁻¹, far below the EU standard. The developed substrate also exhibited excellent stability and anti-interference capability.