Exfoliated Molybdenum Disulfide Nanosheet Networks as Sensing Materials for Nitrogen Dioxide Detection

Abstract:

Nitrogen dioxide (NO2) is a gaseous air pollutant linked to respiratory and cardiovascular diseases and environmental problems such as acid rain and tropospheric ozone formation. Reference instruments for measuring NO2 are expensive, highlighting the need to develop low cost sensor technologies for wider scale monitoring of this critical pollutant. Here, we report the development of a scalable sensor using electrochemically exfoliated 2D molybdenum disulfide (MoS2) networks. The sensor can detect a wide range of NO2 concentrations at room temperature, with an experimental limit of detection (LOD) as low as 150 ppb and a theoretical LOD of 1.9 parts per quadrillion (ppq) in dry air. The sensor exhibited approximately 90% response to 1 ppm of NO2 within 10 min of exposure. UV irradiation significantly enhanced the sensor’s recovery time, reducing it from 20 min to less than 2 min. Evaluation of the sensor within a large (∼6.5 m3) atmospheric simulation chamber yielded a similar response and recovery time performance, opening the opportunity for further tests in the chamber under various conditions. Finally, using Density Functional Theory (DFT) calculations, we identified key atomic-scale structures and processes highlighting the importance of electrochemically exfoliated sulfur-deficient MoS2 for sensitive room temperature NO2 detection.