NH3 Sensor Based on rGO-PANI Composite with Improved Sensitivity

Abstract

This work reports on a reduced graphene oxide and poly(aniline) composite (rGO-PANI), with rGO clusters inserted between PANI chains. These clusters were formed due the plasticizing effect of N-methyl-2-pyrrolidone (NMP) solvent, which was added during the synthesis. Further, this composite was processed as thin film onto an interdigitated electrode array and used as the sensitive layer for ammonia gas, presenting sensitivity of 250% at 100 ppm, a response time of 97 s, and a lowest detection limit of 5 ppm. The PANI deprotonation process, upon exposure to NH3, rGO, also contributed by improving the sensitivity due its higher surface area and the presence of carboxylic acids. This allowed for the interaction between the hydrogen of NH3 (nucleophilic character) and the -COOH groups (electrophilic character) from the rGO surface, thereby introducing a promising sensing composite for amine-based gases.

Phthalocyanines and Porphyrins/Polyaniline Composites (PANI/CuPctBu and PANI/TPPH2) as Sensing Materials for Ammonia Detection

“…It is also worth noting that exposure times are relatively short in some of these examples, meaning that the steady state is sometimes not achieved [ 39 ]. The short response times reported by some studies in Table 1 are explained by either the ultra-thin film structure [ 35 ], the combination of the different elements of the composites [ 37 ], or the synergetic effect of the protonation process [ 40 ].…”

Pt/MoS2/Polyaniline Nanocomposite as a Highly Effective Room Temperature Flexible Gas Sensor for Ammonia Detection

“…Whereas, the low sensitivity, slow response/recovery rate, and unsatisfactory long-term stability is still lacking for the pristine PANI NH 3 gas sensors. Some strategies have been proposed to design ideal PANI-based composites NH 3 sensors, including constructing p–n heterojunctions with metal oxide semiconductors (WO 3 , SnO 2 , CeO 2 , TiO 2 , ZnO, Fe 2 O 3 ) to change the energy band structure, composites with conductive carbon materials (rGO, CNTs) to accelerate charge transfer, and form Schottky barrier with noble metals (Au, Pd) to exert a synergistic effect between the components. However, there are few reports on the combination of PANI with two-dimensional (2D) materials to achieve highly sensitive detection of NH 3 .…”

Fabrication of flexible carbon dioxide gas sensor with conductive polymer/reduced graphene oxide hybrids: Effects of substrate type and mass ratio

“…13 In addition to that, the interaction/ affinity of the gas molecules with the nanomaterials used for the sensing application will decide the ultimate selectivity and sensitivity. [14][15][16] For instance, graphene is highly selective to NH 3 due to the interaction between the H of NH 3 (nucleophilic character) and the COOH (electrophilic character) of the graphene. 16,17 Despite having excellent properties, pristine rGO has longer response and recovery time possibly due to the slow desorption of the target gas molecules on the rGO surface; hybridizing rGO with foreign substances to form a nanocomposite can potentially increase the gas sensing properties.…”

“…[14][15][16] For instance, graphene is highly selective to NH 3 due to the interaction between the H of NH 3 (nucleophilic character) and the COOH (electrophilic character) of the graphene. 16,17 Despite having excellent properties, pristine rGO has longer response and recovery time possibly due to the slow desorption of the target gas molecules on the rGO surface; hybridizing rGO with foreign substances to form a nanocomposite can potentially increase the gas sensing properties. 18,19 One of the most promising candidates to cross-link with rGO is polyaniline (PANI), which exhibits excellent electrical conductivity, redox properties, superior flexibility, and good stability at room temperature.…”

“…The availability of such defects will improve the adsorption and interaction of rGO with the different type of gases, leading to improved gas sensing properties 13 . In addition to that, the interaction/affinity of the gas molecules with the nanomaterials used for the sensing application will decide the ultimate selectivity and sensitivity 14–16 . For instance, graphene is highly selective to NH 3 due to the interaction between the H of NH 3 (nucleophilic character) and the COOH (electrophilic character) of the graphene 16,17 …”