Transition metal doped 2D SiC (TM=Ag, Pd and Rh) as a potential candidate for NOx (x = 1,2) and NH3 sensing

Abstract

To control the nitrogen oxide emissions in large power plants, accurate monitoring NOx and NH3 gases at the outlet of the selective catalytic reduction system is vital to determine the degree of NOx reaction and adjust the amount of injected NH3. In this study, transition-metal (TM) atoms (Ag, Pd and Rh) doped 2D graphene-like SiC monolayers have been designed based on first-principles calculations. The adsorption and detection characteristics of TM-doped 2D SiC monolayers for NOx (x = 1, 2) and NH3 were systematically investigated. It is found that TM-doped 2D SiC monolayers exhibit strong potential in developing chemical sensors capable of detecting NO, NO2 and NH3. With the decoration of TM atoms in SiC monolayers, the adsorption ability of NO, NO2 and NH3 could be enhanced ascribed to the increased adsorption energy and electrical conductivity. In addition, the TM-SiC monolayers exhibit desirable thermostability at 298 K, 498 K and 798 K. By comparing the variations in atom-to-atom distances, plane-averaged charge density differences, charge transfers, density of states, energy gap variation and the recovery times of TM-doped SiC before and after adsorbed NOx and NH3, we found that Pd-SiC, Ag-SiC and Rh-SiC are optimal for the detection and recovery of NO, NO2 and NH3 gases with adsorption energies − 1.82 eV, − 2.17 eV, − 1.10 eV, respectively.