Ab initio study of CNT NO2 gas sensor

NO2 gas adsorption, diffusion, and reaction on a single walled carbon nanotube (SWNT) surface are studied using ab initio simulations. The small diffusion barriers of NO2 on SWNT surface suggest that NO2 molecules can produce NO and NO3 through chemical reactions. From the estimation of diffusion barriers and binding energies of NO2, NO, and NO3 on a SWNT surface, we show that NO3 is the most likely long-lived species on SWNT. This finding enables us to explain why the experimental recovery times of NO2 gas sensors have been measured to be as long as 12 h.