Ammonia gas adsorption study on graphene oxide based sensing device under different humidity conditions

Abstract

Herein, we investigated ammonia (NH3) sensitivity of graphene oxide (GO) based sensing device through experimental and theoretical techniques. The Modified Hummer's method was employed for the preparation of GO. The physical and chemical properties of GO were studied by using XRD, SEM/TEM, FT-IR, Raman, TGA/DSC. The BET surface area of GO sheets was found to be 37.24 m2/g. The GO sensing device was exposed to various ammonia concentrations ranging from 100 to 400 ppm. We have found the ammonia gas sensitivity of the GO has increased from 45 to 58% when the ammonia concentration was increased from 100 to 400 ppm. The ammonia sensitivity measurements were carried out under different humidity conditions and the sensitivity of GO was found to increase from 36 to 68% when the humidity level was increased from 11% to 75%. The interaction energy for the adsorption of NH3 by different functional groups (such as OH, -O-, COOH) on GO was calculated by using density functional theory. The interaction energy of carboxyl and hydroxyl groups found to be 46 kJ/mol and 37 kJ/mol respectively. The computation results were revealed that the hydroxyl and carboxyl groups are energetically more favorable for the adsorption of NH3 than the epoxy group on GO.