Carbon molecular sieve-functionalized graphene sensors for highly sensitive detection of ethanol

Abstract

The surface functionalisation of graphene enables its application for the facile detection of low-concentration volatile organic compounds. Herein, we demonstrated that the carbon molecular sieve (CMS) functionalisation of graphene nanoribbons (GNRs) prepared using chemical vapour deposition (CVD) enhances their ethanol gas sensing performance by three orders of magnitude. The presence of the CMS layer on the GNRs was confirmed using helium ion microscopy and Raman spectroscopy. The porosity of the CMS functionalization of GNRs was confirmed using transmission electron microscopy. Unlike the CVD GNR field-effect transistor (FET), the CMS-functionalised GNR FET (CMSF-GFET) showed a sensitivity of 50 ppb, and the sensing performance improved with an increase in temperature. The high sensitivity of the CMSF-GFET can be attributed to the catalytic activity of the CMSs and the dipole interaction between the adsorbed ethanol molecules, which led to enhanced graphene-ethanol charge transfer and van der Waals interaction. The dependence of this charge transfer on the applied tuning voltage was investigated using the charge neutrality point disparity (CNPD) method. It was found that the CNPD value increased with an increase in the ethanol gas concentration, confirming that the CMS functionalisation induced the dipole interaction between the adsorbed ethanol molecules and the GNR surface.