Vasudeo Babar

MXenes are a promising class of two-dimensional materials with several potential applications, including energy storage, catalysis, electromagnetic interference shielding, transparent electronics, and sensors. Here, we report a novel Mo2CTx MXene sensor for the successful detection of volatile organic compounds (VOCs). The proposed sensor is a chemiresistive device fabricated on a Si/SiO2 substrate using photolithography. The impact of various MXene process conditions on the performance of the sensor is evaluated. The VOCs, such as toluene, benzene, ethanol, methanol, and acetone, are studied at room temperature with varying concentrations. Under optimized conditions, the sensor demonstrates a detection limit of 220 ppb and a sensitivity of 0.0366 Ω/ppm at a toluene concentration of 140 ppm. It exhibits an excellent selectivity toward toluene against the other VOCs. Ab initio simulations demonstrate selectivity toward toluene in line with the experimental results.

Two-dimensional materials can be utilized to detect gas molecules in low concentration due to their high surface-to-volume ratios. In this respect, we investigate in the present work recently fabricated borophene, two-dimensional B, which has buckled and line-defective phases. Both are systematically studied for four gas molecules: NH3, NO, NO2, and CO. In each case, the adsorption energy is found to be high and borophene develops distinct wrinkles. Our results provide a thorough understanding of the interaction between borophene and the gas molecules. An excellent performance of borophene as gas sensor is demonstrated by simulating the material’s transport characteristics by means of the nonequilibrium Green’s function method.

First-principles calculations are performed to compare the adsorption of CO, NH3, NO, and NO2 molecules on monolayer, bilayer, and heterobilayer MoS2 and WS2, using van der Waals corrected density functional theory. Only minor differences are demonstrated for the adsorption behaviors of the monolayer and bilayer systems despite fundamental differences in the electronic structure (direct versus indirect band gap). We also show that NO2 binds stronger to the sensor materials than the other gas molecules, resulting in enhanced charge transfer. Adsorption of paramagnetic NO and NO2 has significant impact on the electronic states, in contrast to adsorption of nonmagnetic CO and NH3.

We demonstrate that the thermal conductivity is massively reduced in monolayer C₃N as compared to isostructural graphene.

Abstract Using density functional theory with van der Waals dispersion correction, the adsorption behavior of common gaseous pollutants (CO, NO, NO 2 , and NH 3 ) on monolayer C 3 N is investigated. The adsorption sites and energies, binding distances, charge transfers, and electronic band structures are calculated to understand the influence of the adsorbed molecules on the transport properties of monolayer C 3 N. The current–voltage characteristics are calculated using the nonequilibrium Green's function formalism. It turns out that all investigated molecules are physisorbed on monolayer C 3 N and that NO and NO 2 gases can be sensed with high sensitivity. The recovery time of the sensor is found to be outstanding in the case of NO sensing (2.4 μs at room temperature) and competitive to other materials in the case of NO 2 sensing.