C3N monolayers as promising candidates for NO2 sensors

Searching for suitable materials for NO2 sensing has important scientific significance and application value. First-principles calculations have been performed on the adsorption of NO2 and its various interfering gases on the pristine C3N monolayer (p-C3N) and the B-doped C3N monolayer. The studies on the adsorption stability, geometric structure, charge transfer, and electronic structure indicate that the p-C3N is a promising room-temperature NO2 sensor, with high selectivity and sensitivity, and good reversibility. For the B-doped C3N monolayer, the calculated formation energies suggest that B doping into the C3N lattice is thermodynamically highly favorable. Furthermore, B doping by replacing the N atom in the C3N monolayer should can further improve the sensing selectivity and sensitivity of the C3N monolayer toward NO2. However, it is noted that a large adsorption energy for NO2 indicates that the B-doped C3N monolayer may be reversibly operated above the room temperature. The possible reason for the distinct adsorption behaviors of the various molecules is also provided. Our theoretical studies indicate the great potential of the C3N-based two-dimensional semiconductor as good NO2 gas sensors.