Transition-metal single atom catalyst embedded in C2N for toxic-gas reduction reaction and selective gas-sensing application: Atomic-scale study

Abstract

Exploring advanced materials for detecting noxious gases is a key requirement for maintaining healthy air quality in the environment. The catalytic activity of four magnetic transition metal “TM” elements (e.g., Mn, Fe, Co and Ni) embedded in C2N pores, as single-atom catalysts (SAC), has been tested towards detecting toxic oxidizing gases. As a model, we tested the sensing efficiency of these catalysts towards two toxic gases, namely NO and NO2. For our calculations, we have used a formalism based on the combination of density functional theory (DFT) and non-equilibrium green’s function (NEGF). From our findings we have drawn a strong correlation between the sensor response and the reduction in magnetization (ΔM ≅ −1.40 to −0.55 μB). The results of spin-polarized transport properties showed that Ni- and Fe-embedded C2N are the most efficient in detecting NO/ NO2 and NO2 molecules (with ΔM/M0 = −98%, −38% to −18%, respectively). The main reason for the magnetization reduction was the formation of chemical bonds between SAC and molecules thereby causing an enormous reduction in the number of unpaired d-electrons. Thus, Fe- and Ni-C2N are recommended for either toxic-gas reduction reactions or platform materials in disposable gas sensors for efficient capturing of toxic gases.