A transition metal (Ti, V, and Mn)-decorated CrS monolayer as a propitious gas scavenger for SF decomposition remnants: acumen from density functional theory simulations.

Developing a sensitive and selective gas sensor for the detection of SF gas decomposition products in a gas-insulated switchgear is crucial for environmental protection and human health. This study delves into the adsorption of HS, SO, SOF, and SOF gases over the pristine and transition metal (TM = Ti, V, and Mn)-decorated monolayer CrS using the first principles method. The TM decoration strategy is adopted to improve the adsorption capacity of the pristine CrS monolayer. The optimal doping positions for the TMs on the CrS monolayer were identified, with the most stable configuration occurring directly above the Cr atom. The results show that the TM-CrS monolayers are energetically stable, with negative binding energies, and the highest (-5.546 eV) and Δ (-0.231e) values were observed for Mn decoration. Thermal stability of the TM-decorated CrS monolayers at ambient temperature (300 K) was confirmed by molecular dynamics (AIMD) simulations. The assessment of the mechanical properties reveals that the decorated monolayers are mechanically stable with high values of bulk moduli. It is observed that the TMs not only alter the magnetic state but also induce a significant reduction in the electronic band gap of the CrS, which is highly beneficial for gas sensing applications. After introducing TMs, the adsorption process shifted from physisorption to chemisorption with the formation of strong chemical bonds between the adsorbate and adsorbent. The values for Ti increase from -0.200 eV to -3.258 eV, for V from -0.200 eV to -3.21 eV, and for Mn from -0.200 eV to -2.645 eV. The adsorption mechanism of the gas-adsorbent interactions was revealed by analyzing metrics such as energy band structures, charge transfer, charge density difference, and partial density of states plots. Upon adsorption of gases, the band gap of TM-decorated CrS monolayers undergoes considerable changes, suggesting high sensitivity for these gases. For the investigated SF decomposition components, the Mn-CrS sensor exhibits ideal recovery times and excellent sensitivity values; at room temperature, the sensing response of the monolayer Mn-CrS to SOF reaches a high value of 256.318. Taking into account the balance of adsorption strength, sensitivity, and recovery time, monolayer Mn-CrS emerges as a sustainable and recyclable gas sensor for detecting SF decomposition gases in electrical equipment.