Oxygen vacancies-driven signal enhanced photoelectrochemical sensor for mercury ions detection

Mercury ion (Hg2+) poses a serious threat to human health due to its high toxicity. In this study, a smartphone-based photoelectrochemical sensor based on oxygen vacancies (OVs) driven signal enhancement for mercury ion detection was designed. BiVO4-x/Bi2S3/AuNPs were combined with T−Hg2+−T recognition mode to construct a multi-sandwich photoelectrochemical sensor. On the one hand, the OVs can increase the adsorption of light by the materials and enhance the photocurrent response as well as the superconductivity of Au NPs to accelerate the charge transfer at the electrode interface. On the other hand, the multi-sandwich structure was exploited to increase the binding site of Hg2+, as well as the T−Hg2+−T structure for sensitive recognition of Hg2+ and signal amplification. The sensor showed good linearity for Hg2+ concentration in the range of 0.1 nM–1.0 μM with a detection limit of 4.8 pM (S/N = 3). Eventually the smartphone-based real-time detection sensor is expected to contribute to the future analysis of heavy metal ions.