Tailoring gas sensing properties of WS₂ monolayer via Nb and Co embedding for highly sensitive and selective detection of HCN and H₂S gases: a first principle study

We report on the adsorption performances of HCN, H2S, HF, and H-2 gases on Nb and Co embedded WS2 monolayer using density functional theory calculations. The adsorption configurations, adsorption energy, charge transfer, density of state, band structure, and recovery time were studied to evaluate the possible tailoring of gas sensing properties to improve sensitivity and selectivity of the WS2 monolayer. The results show that HCN exhibits better adsorption on the Nb-embedded WS2 with an adsorption energy of -1.09 eV and charge transfer of -0.18 e, whereas H2S shows superior adsorption on the Co-embedded WS2 with an adsorption energy of -1.1 eV and charge transfer of 0.23 e. Better sensitivity and selectivity were recorded for the adsorption of the HCN and H2S on the Nb and Co-embedded WS2 monolayer respectively. At 398 K, the recovery times for the two sensing systems are 54 s and 61 s for Nb-embedded WS(2)with HCN and Co-embedded WS2 with H2S respectively making them suitable for gas sensing applications. The study reveals the promising capabilities of Nb-embedded WS2 and Co-embedded WS2 in detecting HCN and H2S, respectively. In addition, it thoroughly investigates the influence of surface modifications on the characteristics of gas sensors.