Enhanced ammonia/amines sensitivity at room temperature using plasma polymerized polyvinyl acetate-reduced graphene oxide composite film sensors

Abstract

Amines and ammonia can harm the environment, even in small concentrations. Efficient amine sensors are required to monitor the quality of food and air. A growing number of industries need sensors that can recognize a particular gas. Here, we demonstrate composite films made of plasma polymerized vinyl acetate (PVAc) and reduced graphene oxide (rGO) to address the crucial issues of limited selectivity, long-term instability, and temperature instability in chemoresistive gas sensors. Change in resistance of the sensor was studied in presence of analyte gas. An inductively linked plasma polymerization setup prepares PVAc films under carefully calibrated deposition conditions. Several samples are analysed to determine the ideal PVAc to rGO ratio for the composite film. Compared to individual PVAc and rGO films, final samples have demonstrated a sensitivity to ammonia and amines up to 15 times higher. The sensitivity of measuring ammonia/amines ranges from 628 for trimethylamine to a maximum of 3389 for methylamine. The sensitivity of measuring ammonia is 1621, while the sensitivity of measuring dimethylamine is 2041. The redox reaction, charge transfer, and swelling of polymer films explain potential sensing processes. Ammonia/amine selectivity has been enhanced by up to 160 compared to other volatile organic compounds (VOCs) using PVAc-rGO composite films. Based on unique selectivity, these films may also successfully distinguish between ammonia and other amines. It is shown that fluctuations in temperature between 30 °C and 150 °C did not affect the sensitivity of PVAc-rGO films. These films remain sensitive for far longer than three months. As a result, composite films of PVAc-rGO may be used to fabricate exceptionally sensitive and reliable gas sensors for ammonia/amines environmental monitoring.