WS2 nanosheets decorated multi-layered MXene based chemiresistive sensor for efficient detection and discrimination of NH3 and NO2

Abstract

Unsatisfactory sensing performance in terms of lack of selectivity and cross-sensitivity to humid environment remains a challenging issue for Ti3C2Tx MXene-based sensors. In this direction, the present study investigates the WS2/MXene composite-based chemiresistive sensor, utilizing the synergistic benefits of active adsorption sites of WS2 nanosheets with large surface and high conductive platform of multi-layered MXene sheets. The different weight proportions of WS2 to MXene were synthesized and a sensor fabricated using 25 wt % WS2/MXene exhibited preeminent response of 3–29 % and 6.87–44 % within range of 0.1–5 ppm NH3 and 1–100 ppb NO2, respectively. More importantly, the opposite transient response curves were observed for NH3 (increase in resistance) and NO2 (decrease in resistance), which served as a basis for their discrimination. Further, density functional theory simulations were performed to better comprehend the gas detecting capabilities of material, showing the high adsorption energies of WS2/MXene surface towards NH3 and NO2. Moreover, the humidity cross-sensitivity studies with NH3 and NO2 were also taken, and the sensor showed high resilience to humidity. Finally, an LED sensing module was employed to further distinguish the detection of NH3 and NO2, which showed the possibility of practical application of dual sensing using single sensing material.