First principle insight into co-doped MoS2 for sensing NH3 and CH4

Abstract

In this work we present the atomistic computational study of the adsorption properties of Co doped MoS2 adsorbed ammonia (NH3) and methane (CH4). The adsorption distance, adsorption energy (Ead), charge transfer (Qt), bandgap, Density of States (DOS), Projected Density of States (PDOS), transport properties, sensitivity and recovery time have been reported. The diffusion property of the system was calculated using Nudge Elastic Band (NEB) method. The calculated results depict that after suitable doping of Co on MoS2 monolayer decreases the resistivity of the system and makes it more suitable for application as a sensor. After adsorbing NH3 and CH4, Co doped MoS2 bandgap, DOS and PDOS become more enhanced. The adsorption energy calculated for NH3 and CH4 adsorbed Co doped MoS2 are -0.9 eV and -1.4 eV. The reaction is exothermic and spontaneous. The I-V curve for Co doped MoS2 for CH4 and NH3 adsorption shows a linear increase in current up to 1.4 V and 2 V, respectively, then a rapid decline in current after increasing a few volts. The Co doped MoS2 based sensor has a better relative resistance state, indicating that it can be employed as a sensor. The sensitivity for CH4 and NH3 were 124 % and 360.5 %, respectively, at 2 V. With a recovery time of 0.01s, the NH3 system is the fastest. In a high-temperature condition/environment, the Co doped MoS2 monolayer has the potential to adsorb NH3 and CH4 gas molecules. According to NEB, CH4 gas molecules on Co doped MoS2 has the lowest energy barrier as compared to NH3 gas molecules. Our results indicate that adsorbing NH3 and CH4 molecules in the interlayer is an effective method for producing Co doped MoS2 monolayers for use as spintronics sensor materials.