Variable valence Ce3+/Ce4+ ionic bridge boosted interfacial charge transfer for efficient photoelectrochemical profenofos aptasensing

Given the health risks posed by profenofos (PFF) pesticide residues in aquatic environments, photoelectrochemical (PEC) aptasensors provide a viable solution for efficient detection, with accelerated photoelectrode interfacial carrier migration being critical for high-sensitivity sensing. A variable-valence Ce 3+ /Ce 4+ ionic bridge-modified carbon nitride (CN) material was engineered for PEC aptasensing applications. As a rare-earth species, Ce 3+ /Ce 4+ features incompletely filled 4 f and unoccupied 5d orbitals, which induce electron trap states in the CN matrix. These states restructure CN’s band configuration, narrow its band gap, and enhance photogenerated charge carrier generation. Moreover, Ce 3+ /Ce 4+ ionic bridge serves as an efficient electron transport medium, boosting charge migration and diffusion across the CN surface, thus elevating the material’s overall PEC performance. The resulting Ce 3+ /Ce 4+ /CN-based PEC aptasensor achieved sensitive PFF detection, with a linear range of 1–30000 fM and a detection limit of 0.33 fM (S/N = 3). It also exhibited strong selectivity, stability, reproducibility, and a low relative standard deviation (RSD=4.89% < 5%). This strategy enables effective aquatic PFF residue determination, while the valence-reversible ion-doped CN holds promise for broader rapid PEC analysis of organophosphorus pesticides.