One-pot synthesis of a CdS-reduced graphene oxide–carbon nitride composite for self-powered photoelectrochemical aptasensing of PCB72

Abstract

Graphitic carbon nitride (C₃N₄) is a carbon-based metal-free semiconductor, which has been widely explored as a photoactive material. In this work, the CdS, reduced graphene oxide (rGO) and C₃N₄ (CdS–rGO–C₃N₄) composite was synthesized by a simple one-pot hydrothermal method and utilized to construct a photoelectrochemical (PEC) sensor. Compared with CdS, C₃N₄ and CdS–C₃N₄, the CdS–rGO–C₃N₄ composite exhibited enhanced photoelectrochemical (PEC) performance, due to the expanded absorption of C₃N₄ in the visible region by CdS and promoted the charge carrier separation of a photoelectrode by rGO. Based on a glassy carbon electrode (GCE) modified with CdS–rGO–C₃N₄ and a PCB72-binding aptamer (ap/CdS–rGO–C₃N₄/GCE), a PEC aptasensor for the detection of 2,3′,5,5′-tetrachlorobiphenyl (PCB72) was developed. When H₂O₂ was added into the electrolyte, the PEC sensor exhibited an amplified response toward PCB72, and could be operated in a self-powered mode at a potential of 0 V. Under optimum conditions, the constructed PEC aptasensor exhibited a wide linear range of 10 to 1000 ng mL⁻¹ for PCB72 detection, with a low detection limit (S/N = 3) of 1.0 ng mL⁻¹. Moreover, this aptasensor exhibited high selectivity, good reproducibility and high stability. The applicability of the developed PEC strategy was demonstrated by determining PCB72 in environmental water.