Gas Sensing and Capturing Based on the C ₇N ₆ Monolayer with and Without Metal Decoration: A First-Principles Investigation

Abstract

We have investigated the geometrics, energetics, charge transfer, ELF, EDD, work function, electronic and gas sensing and capturing properties of the pure and metal-decorated C₇N₆ monolayers toward gases like NO₂, SO₂, NO, NH₃, H₂O, H₂S, CO, CH₄, CO₂ and N₂ by means of first-principles calculations. It is discovered the pristine C₇N₆ monolayer is not suitable for gas sensing and capturing materials. The Li decoration on the C₇N₆ monolayer is energetically and kinetically favorable, and remarkably enhances the adsorption strength of toxic gases (NO₂, SO₂, NO, and NH₃), which in turn significantly influences the electronic properties (particularly conductivity) of the Li-decorated monolayer with apparent charge transfer and changes in work functions. Based on the analysis of recovery time, adsorption strength, changes in electronic properties and work function, the capture capacities and the influence of humidity on the sensing and capturing properties of NO₂, SO₂, NO, and NH₃ on the monolayer, the Li-decorated C₇N₆ monolayer would be a promising potential of highly sensitive gas sensing and capturing materials for NO and NH₃ gases, and an effective scavenger of NO₂ and SO₂ in specific scenarios in dry environment that call for experimental evaluation.

Keywords: C7N6 monolayer, Adsorption, gas sensing and capture, metal modification, Electronic properties