Oxygen-functionalized MoSe2 nanoflowers for selective detection of xylene at room temperature

Abstract

The selective detection of xylene among its chemically similar counter VOCs is very crucial, and challenging and has great implications in breath analysis. At this point, we are introducing MoSe2 nanoflowers, which are synthesized by a one-step hydrothermal method. Later on, the surface functionality of the as-grown MoSe2 was effectively modulated by purging different oxygen concentrations (0.25 to 20 % O2) at 200 °C. Microscopic and spectroscopic characterizations were used to identify the changes in nanostructures after oxygen functionalization. The MoSe2 sensor treated with 2.5 % O2 showed an enhanced response towards xylene (73 % at 100 ppm) that was 14 times higher than the pristine MoSe2 at room temperature. Notably, the 2.5 % O2-treated MoSe2 sensor exhibited an 8 % response in 100 ppb of xylene with a lower detection limit (LOD) of 83 ppb. The cross-sensitivity of the sensor towards xylene as compared to the chemically identical VOCs like benzene and toluene was found to be very high. The selective detection of xylene was attributed to the improved surface reaction sites and catalytic behavior of MoSe2 after oxygen functionalization. The study confirms that the introduction of sufficient oxide or oxidants in 2D selenides like MoSe2 is favorable to accomplishing superior gas sensing characteristics.