Real-time detection of mercury ions based on vertically grown ReS_(2) film

Mercury(Hg^(2+)),one of the most dangerous toxins in water,is a heavy metal that causes organ damage from both short-term and chronic exposure.Conventional methods for detecting mercury such as atomic absorption spectrometry or Raman spectroscopy require bulky equipment with complicated procedures.In this work,we fabricated a highly sensitive,real-time thin-film sensor based on vertically aligned rhenium disulfide(ReS_(2)).Its outstanding large surface area and the unique electronic appearance of its layered architecture make a ReS_(2) nanosheet a strong contender for such an application.The sensor exhibited a fast response speed(<2 s)to Hg^(2+)and an ultralow detection limit of 4 nM,which is significantly less than that of the U.S.Environmental Protection Agency's(U.S.EPA)allowed utmost contamination limit for Hg^(2+)in drinking water(10 nM).It also exhibited strong selectivity for Hg^(2+)against other metal ions such as Na^(+),Zn^(2+),Fe^(3+),Cu^(2+),Ca^(2+),Ni^(2+),Ag+,Cd^(2+),Fe^(2+),and Pb^(2+).Because this nanosheet can be replaced with any secondary substrate and possibly patterned into a microscale size,the sensor can be integrated into multiple platforms such as portable devices or sensor nodes in a grid network.