Design and construction of Z-scheme Bi2S3/nitrogen-doped graphene quantum dots: Boosted photoelectric conversion efficiency for high-performance photoelectrochemical aptasensing of sulfadimethoxine

Abstract Rational design and fabrication of Z-scheme visible-light-driven photoactive materials have drawn much attention owing to their great potential in handling environment and energy crisis. In this work, Z-scheme Bi 2 S 3 /nitrogen-doped graphene quantum dots (NGQDs) with superior photoelectric conversion efficiency were designed and fabricated, which demonstrated enhanced photoactivity compared with Bi 2 S 3 owing to the improved separation efficiency of photogenerated electron and hole pairs. The emphasis was put on designing Z-scheme Bi 2 S 3 /NGQDs, and then the mechanism of Z-scheme charge transfer mode was verified by the electron spin resonance (ESR) technique. On this basis, the proposed sensor exhibited a wide linear range of 0.1–120 nM and a detection limit of 0.03 nM (S/N = 3) for SDM, with high sensitivity (0.075 μA nM –1 ), good selectivity and stability. Moreover, the proposed PEC aptasensor using Bi 2 S 3 /NGQDs as the photoelectrode achieved sensitive and selective determination of sulfadimethoxine in milk samples. This work could provide some ideas for designing other Z-scheme photoactive species and insights into the charge transfer mechanism of Z-scheme. Furthermore, the promising applicability of PEC aptasensor using photoactive species could be extended to other accurate monitoring for contaminants.