Covalent functionalization of MoSe₂ nanosheets with hydrogen bond-donating functionalities for the sensing of nitroaromatics

Nitroaromatic compounds serve as indicators of environmental pollution and are specifically related to contamination by pesticides and explosive residues. Consequently, the development of sensitive sensing materials for their detection is of significant interest in environmental monitoring. This study investigates the chemical functionalization of molybdenum diselenide (MoSe₂) with organic halogenated groups possessing hydrogen-bonding donor functionalities (i.e., –CONH₂, –CO₂H, and –SO₃H), with the objective of employing them as sensing materials for the detection of selected nitroaromatics, including nitrobenzene (NB), m-nitrotoluene (m-NT), p-nitrotoluene (p-NT), p-nitrophenol (p-NP), picric acid (TNP), and p-nitroaniline (p-NA). These findings indicate that the chemical tethering of functional alkyl groups enhances physical adsorption, with chemical reaction energies 100 times greater than the physical adsorption energies. Electronic properties, such as the density of states (DOS), projected DOS, and band structures, demonstrate significant alterations in conduction and bandgap modulation, with a reduction of 0.5 eV. In the presence of target molecules, high adsorption energies were observed, particularly in the range of –1.84 to –2.26 eV, notably for MoSe₂/2c bearing the –SO₃H moiety. The partial charges, electronic density differences, and recovery times further corroborated the potential application of these materials in assessing pollution by nitroaromatic compounds for environmental monitoring in ecosystems.