Core-shell LaFeO3@g-C3N4 p-n heterostructure with improved photoelectrochemical performance for fabricating streptomycin aptasensor

The development of core-shell heterostructure photoactive materials with high visible light response and charge separation efficiency is of great significance. Herein, we prepared LaFeO3@g-C3N4 p-n heterojunction with core-shell structure by using facile one-step method. As a contrast, g-C3N4 nanosheets decorated with LaFeO3 nanoparticles (LaFeO3/g-C3N4) were synthesized by a reported method. The LaFeO3@g-C3N4 heterostructure boosted the visible light response and effectively separated charge carriers compared to LaFeO3/g-C3N4. Moreover, for LaFeO3@g-C3N4 heterostructure, the interaction of core-shell interface and synergistic effect of p-n heterojunction made photoelectrochemical (PEC) properties more stable and excellent. Concretely, the absorption band edge of LaFeO3@g-C3N4 heterostructure was about 700 nm, which was wider than LaFeO3/g-C3N4. Additionally, the photocurrent signal of LaFeO3@g-C3N4 heterostructure was 2.3-fold higher than that of LaFeO3/g-C3N4. Thus, on the basis of the prominent PEC performance of LaFeO3@g-C3N4 heterostructure, we constructed a PEC aptasensor to detect streptomycin (STR) sensitively and selectively. The aptasensor revealed a wide linear concentration range from 0.01 nM to 10000 nM of STR, with a low detection limit of 0.0033 nM (S/N = 3). The fabricated aptasensor had excellent stability, practicability, and reproducibility, laying a good foundation for STR detection in other analytical fields.