Gas Sensing Properties Study Of Graphene/Polyaniline Composites Basedon Multi Scale Analysis

Conducting polymers such as polyaniline（PANI）are suitable sensing materials for ammonia due to its fast response and low cost,while the interaction mechanism between ammonia and Graphene-based system is still not clear.In this work,the interaction mechanism between NH₃ and Graphene/PANI nanocomposites was investigated by using multi-scale analysis method combining molecular dynamics and first-principles,and the adsorption of ammonia at different locations of pure polyaniline and Graphene/PANI composites are analyzed.The band gap for Graphene/PANI system shows more significant change after adsorption than that of pure polyaniline,which indicates a higher sensitivity for detecting ammonia.The results of sorption isotherm imply that Graphene/PANI system exhibits more adsorption capacity for ammonia.Moreover,the diffusion coefficient of ammonia in Graphene/PANI is much large than pure polyaniline,which demonstrating that that gas diffusion occurs more easily in nanocomposite structures.The results are verified by experimental data.The gas sensing properties of multiple gases（CO,NO,H₂）of Graphene/PANI are calculated and compared with those of NH₃ Analyses of adsorption energy,Mulliken charge,and density of states indicated that the sensitivity of interaction between the gas molecules and the Graphene/PANI nanocomposite as follows:NH₃>NO>CO>H₂.By comparing the sorption isotherms and diffusion coefficients,the Graphene/PANI exhibit excellent adsorption capacity towards NH₃ gas molecules.These results mean that Graphene/PANI is more selective for NH₃ because of its high sensitivity and adsorption energy.These calculation theories will provide an effective reference for the development and production of high performance composite gas sensors.