Photo-Assisted Selective and Reversible Acetone Sensors Based on 2-D MoSe₂ Nanoflakes

Selective and ultrasensitive detection of volatile organic compounds (VOCs) is crucial for environmental monitoring and non-invasive medical diagnosis. We report herein a two-dimensional (2D) molybdenum diselenide (MoSe<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub>) nanoflakes based chemiresistive acetone (CH<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub>COCH<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub>) sensor that reveals a response of 32.26 % for 181 ppm of acetone and a limit of detection of 6.84 ppb at room temperature, with a high selectivity over other common VOCs. However, the high adsorption energy of acetone molecules on MoSe<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> nanoflakes’ surface leads to a relatively higher recovery time of 1980 s with respect to the existing acetone sensors. For that, we propose an optical stimulation induced accelerated desorption process of the chemisorbed acetone molecules from the surface of MoSe<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> nanoflakes, with the recovery time being reduced to 520 s for optimized photo-assisted gas sensing. Finally, the effect of various wavelength excitations on the sensor response is investigated and explained in light of the photo-assisted charge transfer phenomenon. A COMSOL model of this sensor has been simulated using the Finite Element Analysis method to support the proposed explanation in our work. The superior limit of detection and improved recovery time enable our device for ultrasensitive breath analysis.