Photoelectrochemical determination of inorganic mercury ions based on energy transfer between CdS quantum dots and Au nanoparticles

• Photoelectrochemical sensor for Hg2 + was firstly fabricated by energy transfer.
• Photocurrent was decreased by energy transfer between CdS QDs and Au NPs.
• Interference can be neglected for the specific interaction of T–Hg2 +–T.
• A simple and general protocol for PEC detection of metal ions was opened.

A novel photoelectrochemical (PEC) sensor for mercury ions (Hg2 +) was fabricated based on the energy transfer (ET) between CdS quantum dots (QDs) and Au nanoparticles (NPs) with the formation of T–Hg2 +–T pairs. In the presence of Hg2 + ions, a T-rich single-strand (ss) DNA labeled with Au NPs could hybridize with another T-rich ssDNA anchored on the CdS QDs modified electrode, through T–Hg2 +–T interactions, rendering the Au NPs in close proximity with the CdS QDs and hence the photocurrent decrease due to the ET between the CdS QDs and the Au NPs. Under the optimal condition, the photocurrent decrease was proportional to the Hg2 + concentration, ranging from 3.0 × 10− 9 to 1.0 × 10− 7 M, with the detection limit of 6.0 × 10− 10 M.

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