▎ 摘　　要

Conducting polymers such as polyaniline (PANI) are potential sensing materials for ammonia due to their fast response and low cost, however, the corresponding sensing mechanism needs to be studied further. In this paper, molecular dynamic and first-principles simulations are carried out to investigate ammonia sensing mechanisms of polyaniline/graphene heterostructure. The adsorption of ammonia at different locations of pure polyaniline and graphene/PANI composites is analyzed. The band gap for graphene/PANI system shows more significant change after adsorption than that of pure polyaniline, which indicates higher sensitivity for detecting ammonia, and the results of sorption isotherm imply that graphene/PANI system exhibits more adsorption capacity for ammonia. Moreover, diffusion coefficient of ammonia in polyaniline/graphene system is much large than that of pure polyaniline, demonstrating that gas diffusion occurs more easily in the heterostructure. The results are verified by experimental data, and the proposed computational frame can be used to evaluate and design nanocomposite materials for gas sensor. (C) 2019 Elsevier B.V. All rights reserved.