Highly sensitive and selective room-temperature gas sensors based on B6N6H6 monolayer for sensing SO2 and NH3: A first-principles study

Abstract

We applied first-principles calculations and studied the structures and electronic properties of SO2, NH3, H2, N2, CH4, H2O, N2O, CO, CO2, HCN, and H2S molecules adsorbed on the B6N6H6 monolayer to understand its performance as a sensor. The crystalline structure of the B6N6H6 monolayer remains thermodynamic stable under T = 1000 K, and the rippled structure is more stable than the planar one. The NH3 and SO2 molecules are chemically and physically, respectively, adsorbed on the B6N6H6 monolayer with moderate adsorption energy and charge transfer. By adsorbing NH3 and SO2, B6N6H6 monolayer electronic properties (especially conductivity) could be adjusted. Adsorption of other molecules did not have any similar effects. The recovery times of NH3 and SO2 desorption from the monolayer were only 0.42 ms and 1.1 s, respectively, at room temperature. The existence of humidity would have, to a certain extent, influence on the sensing of SO2 or NH3 gas using B6N6H6 monolayer. It is thus predicted that the B6N6H6 monolayer could be a room-temperature NH3 and SO2 sensor in a dry environment with high selectivity and sensitivity and fast response and recovery time. We also believe that the B6N6H6 monolayer will be a good candidate for NH3 work-function-type gas sensors.