One-pot synthesis of graphene-ZnxCd1−xS QDs composites with improved photoelectrochemical performance for selective determination of Cu2+

Graphene-ZnxCd1−xS quantum dots (QDs) hybrid materials were successfully prepared via one-step hydrothermal method. TEM and HRTEM results proved that Zn0.8Cd0.2S QDs with an average size of ∼6 nm were homogeneously dispersed on graphene sheets, which favorited the charge separation and improvement of the photocurrent intensity. The controlled experiments proved that graphene-Zn0.8Cd0.2S/ITO electrode with 2 mg graphene dosage exhibited the highest photocurrent at an applied voltage of 0.2 V. Therefore, a photoelectrochemical sensor was developed to detect Cu2+ using graphene-Zn0.8Cd0.2S/ITO electrode. The sensor exhibited good selectivity and linear relationship from 1 μmol dm−3 to 120 μmol dm−3 with detection limit of 6.5 nmol dm−3 at a signal-to-noise (S/N) ratio of 3.