Eco-friendly synthesis of InSe nanoflakes for NO2 gas sensors with excellent response and high humidity resilience

In this paper, a faster and more environmentally friendly way to produce Indium selenide (InSe) nanoflakes for NO 2 gas sensors utilizing a non-toxic solvent (IPA/DI water) is presented. A simple technique of Liquid Phase Exfoliation was employed for the synthesis of the sensing material. The as-produced InSe nanoflakes were subjected to structural, morphological and compositional analyses with FESEM, XRD, TEM, Raman spectroscopy, EDX, DLS and XPS. These samples were then used in the development of NO 2 gas sensors for real-world applications. Sensors were tested under several conditions, including optimal operating temperature, low NO 2 concentrations, and background humidity. Sensors outperform the state of the art, with a 149.10% response for 1 ppm of NO 2 at an operating temperature of 200℃ and very low response and recovery times. Sensors also exhibit an enhanced response of 237.59% in the presence of 50% R.H. @ 25ºC, little humidity cross-sensitivity in the 25 to 75% R.H. range, with a low limit of detection of 35 ppb. Their high sensitivity and selectivity combined to their ability to operate under ambient moisture, make these sensors promising for monitoring traces of NO 2 in the ambient.