Signal-on sensor using MOF-MoS2 with high-performance photoelectrochemical activity for specific detection of Hg2+

Abstract

Mercury is a common, bioaccumulative, and highly toxic pollutant, and its harmful effects on the human body and environment should not be underestimated. In this study, an enzyme-free photoelectrochemical (PEC) analysis method based on signal-on detection was developed using a novel photoelectrochemically active material, metal–organic framework (MOF)-MoS2, for the specific detection of Hg2+. Driven by visible light, MOF-MoS2 can be used as a PEC sensitizer and Hg2+ recognition probe. With the addition of Hg2+, the active sulfur sites on the MOF-MoS2/F-doped tin oxide surface specifically combined to yield HgS, which was further used for signal amplification and specifically turned on the photocurrent response of the electrode. In addition, the p–n junction formed between the MOF-MoS2/HgS complexes triggered the development of MOF-MoS2 composites in the direction of electron–hole separation, leading to an increase in optoelectronic signals. Importantly, the PEC sensor detected Hg2+ over a wide linear range from 0.01 to 1000 nM, with a limit of detection of 0.25 pM. The fabricated sensor exhibited good stability, excellent reproducibility, and specificity. The PEC platform may provide new insights into the non-intrusive detection of Hg2+ in human and water samples.