Nanoporous Activated Carbon Functionalized Graphene Sensors for Selective Detection of Ethanol

Abstract

Graphene surface functionalization enables the facile detection of low concentration volatile organic compounds (VOCs). Herein, activated carbon functionalization of chemical vapour deposition (CVD) graphene is shown to enhance ethanol gas sensing in CVD graphene by three orders of magnitude. The presence of activated carbon was confirmed via Helium Ion Microscopy, and Raman spectroscopy and porosity were confirmed via Transmission Electron Microscopy (TEM). Unlike CVD graphene, the activated carbon functionalized graphene field effect transistor (aCF-GFET) had a sensitivity of 50 ppb with performance improving with increase in temperature. The extreme activated carbon-induced sensitivity is attributed to the catalytic activity and oxidation of the adsorbed ethanol molecules, consequently inducing higher graphene-ethanol charge transfer and Van der Waals bonding. The dependence of this charge transfer on the applied tuning voltage was investigated using the charge neutrality point disparity (CNPD) method, which shows an increase in CNPD values with increasing concentration, confirming the activated carbon-induced oxidation of adsorbed ethanol molecules.