Amperometric Detection of NH3 by Aromatic SAM Modified Graphene

Ammonia (NH 3 ) is a toxic substance resulting in various acute and chronic effects on individuals. NH 3 detection, monitoring methods, and detection tools are desperately needed. In this work, we improved the ammonia sensing capabilities of graphene films deposited by chemical vapor deposition (CVD) by modifying aromatic self-assembled monolayer (SAM) molecules such as 5-[(3-methylphenyl) (phenyl) amino] isophthalic acid (MeIPA) and 5-(diphenyl)amino] isophthalic acid (PhIPA) on amperometric detection method. Morphological investigations of the films were carried out by optical and scanning electron microscopy (SEM). Surface potential was characterized with Kelvin Probe Force Microscopy (KPFM), and vibrational properties were characterized with Raman Spectroscopy. MeIPA modification increased NH 3 uptake by two times compared to unmodified graphene. The results indicated that the SAM modification enhanced NH 3 molecule adsorption and improved its periodic reversible and reproducible response using the amperometric detection system, indicating that SAM molecules might be a feasible probe for ammonia.