Understanding the gas sensing mechanism of MoSe2 nanoroses and rGO composite-based chemiresistive sensors for room temperature NO2 detection

Abstract

This study presents the synthesis of single-phase 2H-MoSe2 and one-pot synthesis of MoSe2/rGO (MSR) composite used for the detection of environmental pollutants (NO2, NH3, H2S CO2, CO, CH4, CH3COCH3) at ambient temperature (∼25 °C). The gas sensing devices were fabricated on Ti/Pt interdigitated electrodes with different compositions of MSR composite viz. 10 (MSR-10), 20 (MSR-20), and 30 (MSR-30) weight % of rGO. The sensitivity of the p-type MoSe2, rGO and MSR-20 was calculated to be ∼29 %, ∼24 % & ∼38 %, respectively at 4 ppm concentration of NO2. The respective response and recovery time were calculated to be 191/218 s, 225/412 s, and 110/128 s for MoSe2, rGO, and MSR-20 composite at 4 ppm of NO2 gas. The response curve at the lowest detection limit indicates stable performance of the device, which makes it suitable for its real-time application. The response time and recovery time of the composite device are 40 s and 65 s, respectively at 100 ppb concentration of NO2 gas. The sensing device was subjected to 0.1 ppm to 4 ppm of NO2 gas concentration, and the obtained device response was highly repeatable and stable after 60 days. The possible gas sensing mechanism based on charge transfer is proposed for fabricated devices using MSR composite material. The gas sensing device parameters, selectivity, repeatability, sensitivity, and stability show a great potential of MoSe2-rGO composite material in gas sensing.