Photoelectrochemical sensing of catechol based on CdS-DNA-pristine graphene nanocomposite film

A photoelectrochemical (PEC) sensing platform was designed for catechol determination using CdS quantum dots (QDs), DNA and pristine graphene (PGR) nanocomposite film-modified electrode. In such a composite film-based PEC sensor, CdS QDs served as the photoelectric conversion element which produced photocurrent signal under visible light illumination; and DNA was designed as the biological recognition element which improved the PEC response of sensor toward catechol due to the interaction between DNA and catechol. To improve the electron transfer of the composite film, PGR with high electrical conductivity was doped, which significantly amplified the photocurrent signal of sensor. Based on such a CdS-DNA-PGR composite film-modified electrode, catechol showed a linear PEC response proportional to its concentration from 1.0 × 10−8 to 1.0 × 10−6 mol L−1. The detection limit (3S/N) was estimated to be 4.9 × 10−9 mol L−1. The developed PEC sensor was successfully applied to determine trace catechol in water samples.