Enhanced fast response to Hg0 by adsorption-induced electronic structure evolution of Ti2C nanosheet

Abstract

Sensitivity is an important factor to be sensing materials, especially for the chemically inert poisonous Hg0. In this work, we reported that the unpassivated Ti2C nanosheet is a potential candidate as the Hg0 sensing material by using first-principles calculations. The calculation results reveal that the distinct Hg0 adsorption behaviors on the semiconducting Ti2C nanosheet, and the moderate adsorption energy indicates a strong interaction between Hg0 and Ti2C nanosheet with good reversibility at room temperature. Furthermore, the electronic structures of Ti2C nanosheet could be influenced by the Hg0 adsorption, the pristine Ti2C was a semiconductor, and a semiconducting—half-metallic—metallic transition arises when the more Hg0 molecules adsorbed on the Ti2C nanosheet. Moreover, we demonstrated that the changes in electronic behavior bring the fast response of transport properties. The current passing through the adsorption system is about 1 order of magnitude larger than pristine Ti2C at a bias of 0.1 V when one Hg0 molecule is adsorbed on the Ti2C nanosheet. And the current is further increased up to 2 orders with the increase of the Hg0 adsorption concentration on both sides of Ti2C nanosheet. Notably, the electronic transport of the Ti2C nanosheet could be regulated by a low concentration of Hg0 adsorption. Therefore, all our results indicated that the Ti2C nanosheet can be acted as a fast response Hg0 nanomaterials.