Air-stable,all-dry transferred ReS_(2)/GaSe heterostructure-based NO_(2)gas sensor

Two-dimensional(2D)materials have gained considerable attention in chemical sensing owing to their naturally high surface-to-volume ratio.However,the poor response time and incomplete recovery re-strict their application in practical,high performance gas sensors.In this work,we fabricated air-stable ReS_(2)/GaSe heterostructure-based NO_(2)gas sensors with excellent gas sensing response,recovery,selectiv-ity and a low limit of detection(LOD)toward nitrogen dioxide(NO_(2)).The ReS_(2)/GaSe heterostructure was prepared via mechanical exfoliation and an all-dry transfer method.Before the sensing measurements,temperature-dependant transport measurements were carried out.The Schottky Barrier Height(SBH)of the ReS_(2)/GaSe heterostructure was calculated and the corresponding transport mechanisms were dis-cussed.The fabricated gas sensors showed a significant response enhancement with full reversibility to-ward ppm-level NO_(2)(response of∼17%at 3 ppm,a LOD of∼556 ppb)at an operating temperature of(33°C).In particular,the total response and recovery time of the ReS_(2)/GaSe was revealed to be less than 4 min(∼38 s and∼174 s,respectively)for the 250 ppm concentration,which is one of the best response and recovery time toward ppm-level NO_(2).The excellent sensing performances and recovery characteris-tics of the ReS_(2)/GaSe structure are attributed to its efficient charge separation,unique interlayer coupling and desirable band alignments.This atomically thin,ultrasensitive gas sensor that operates at room tem-perature is a strong technological contender to conventional metal oxide gas sensors,which often require elevated temperatures.

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.