Room temperature ammonia gas sensor using ester functionalization of graphene oxide

Abstract

A room temperature ammonia gas sensor has been fabricated by depositing the thin film of Functionalized Graphene Oxide (GO) using Langmuir Blodgett (LB) technique on SiO2/Si wafers. Thermal evaporation technique was used for deposition of aluminum (Al) contacts for measuring the resistance of fabricated thin film. Different concentration of Meta Toluic acid (15 mM, 50 mM, 75 mM) has been used for functionalization of GO. X-Ray Diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR) and Raman spectroscopy were used to characterize the Graphene Oxide (GO) after functionalization. Also, Scanning Electron Microscopy (SEM) was carried out for both GO and functionalized GO. Gas sensing behavior of functionalized GO has been investigated for different concentration of ammonia gas. Sensor response was studied for low concentration (100 ppm) of ammonia gas. Highest response at 100 ppm concentration was found to be ∼12%. Higher concentration of MTA in GO leads to higher response of ammonia gas. This enhanced gas response is attributed to the enhanced ester formation reaction at the surface of sensing film, and more defects and carbon vacancy in functionalized GO, which eventually leads to more interaction with NH3 gas molecules.