Interlinked Polyaniline/ZnO Nanorod Composite for Selective NO₂ Gas Sensing at Room Temperature

Abstract

Chemiresistive gas sensing has attracted extensive research attention in recent years, and the facile low-cost synthesis of sensitive materials is important for realizing practical use. One feasible approach is to create a gas-sensing nanocomposite network by infusing an easily processable conducting polymer into a solution-grown interlinking metal oxide nanomaterial. In this work, a polyaniline (PANi) and ZnO nanorod (NR) composite is synthesized for selective UV-activated NO2 gas sensing at room temperature. The nanocomposite comprises interlinking ZnO NRs that are partially covered by PANi, thus forming a charge transport network with abundant gas adsorption sites. Uniform and interlinking ZnO NRs are grown on a prepatterned silicon substrate by using a hydrothermal method, and PANi is prepared by using an in situ oxidative polymerization method. A PANi/ZnO 0.5 nanocomposite with uniform morphology is obtained by drop-casting a PANi solution on the ZnO NRs. The nanocomposite exhibits selective NO2 gas toward various gases including CH2O, NO, and NH3. The responses are 130% and 20920% for 0.05 and 2.5 ppm NO2, respectively. The low-concentration linear sensitivity is 11.7% ppb–1. Based on the Langmuir adsorption model, the adsorption and the desorption constants are determined to be 7.65 × 10–3 ppm–1 s–1 and 1.07 × 10–2 s–1, respectively. The excellent gas-sensing performance of the PANi/ZnO 0.5 nanocomposite is attributed to the formation of abundant p–n heterojunction adsorption sites.

Improved Ethanol Sensing Performance of α-MnO2 Nanorods at Room Temperature Enabled through PPy Embedding

“…Thus, it occupies the active sites of the pyrrole ring, and therefore, the sensor response decreases. The base resistance of the sensor moderately decreases with increasing relative humidity. − …”

“…Exposure to ethanol increases the base resistance of the sensor, as shown in Figure S8. In considering MP50, a p–n heterojunction is formed by PPy and MnO 2 , resulting in increased electron mobility . The band gap energies of polypyrrole and MnO 2 are 3.8 and 2.3 eV, respectively. , Due to the Fermi energy ( E f ) of MnO 2 differing from that of PPy, electrons in the conduction band of MnO 2 will flow across the interface to the LUMO (lowest unoccupied molecular orbital) of PPy until their Fermi energies equilibrate.…”

NASICON-type Na3Fe2(PO4)3 material for an excellent room temperature CO sensor

“…The linear I-V curve indicated that the current conduction is mainly enforced by the bulk sensing material instead of Schottky contacts. 39,40 Different gases have different response characteristics towards a particular material. First, we observed the influence of various gases (CO, C 2 H 5 OH, SO 2 , NO 2 , H 2 S, NH 3 and CO 2 ) on the gas sensing performance of the NFP sensor in prospect of variation in electrical resistance at room temperature ( 27 1C).…”

Recent advances and potential applications of flexible adsorption and separation materials: A review

“…139 Similarly, enhanced host-guest interactions can effectively improve the material's affinity for NH 3 and SO 2 by functionalizing the microporous polymeric framework with carboxylic acid and amidoxime functional groups. 140 Removal of specific contaminant molecules by directional modulation of the chemical composition of the flexible adsorption framework is a straightforward, efficient strategy. For example, polyaniline and its composites exhibit high NO 2 removal efficiency due to the interaction between amino groups and NO 2 molecules.…”

“…This was attributed to the strong interaction between OS…Br in the flexible frame and SO 2 and the framework swelling of IUPs during adsorption (Figure 8B). 139 Similarly, enhanced host–guest interactions can effectively improve the material's affinity for NH 3 and SO 2 by functionalizing the microporous polymeric framework with carboxylic acid and amidoxime functional groups 140 …”