Self-powered photochemical cathode aptamer sensor based on ZnIn 2 S 4 photoanode and Cu 2 O@Ag@Ag 3 PO 4 photocathode for the sensitive detection of Hg 2

A self-powered photoelectrochemical (PEC) aptamer sensor based on ZnIn S as the photoanode and Cu O@Ag@Ag PO as the sensing cathode is designed for the detection of Hg . An indium tin oxide (ITO) electrode modified with ZnIn S was used instead of a platinum (Pt) counter electrode to provide an obviously stable photocurrent signal. The suitable band gap width of ZnIn S can generate photogenerated electrons well. The unique hydrangea structure of ZnIn S can enhance light absorption and accelerate the separation and transfer of photocarriers. At the same time, Cu O@Ag@Ag PO with excellent electrical conductivity further enhances the photocurrent provided by the ZnIn S photoanode. Because the reducing substances in the biological medium can change the photoanode characteristics of the photoanode interface, the separation of the photoanode and the sensing bicathode is beneficial to improve the anti-interference ability of the sensor. Under optimized conditions, the PEC aptamer sensor realizes the detection of Hg (1 mM-1 fM), and the detection limit is 0.4 fM. In addition, the constructed self-powered PEC sensor has good selectivity, repeatability, and stability, which provides a new idea for the design of the PEC aptamer sensor platform.