Highly Sensitive Sub-ppm CH3COOH Detection by Improved Assembly of Sn3O4-RGO Nanocomposite

Abstract

Detection of sub-ppm acetic acid (CH3COOH) is in demand for environmental gas monitoring. In this article, we propose a CH3COOH gas sensor based on Sn3O4 and reduced graphene oxide (RGO), where the assembly of Sn3O4-RGO nanocomposites is dependent on the synthesis method. Three nanocomposites prepared by three different synthesis methods are investigated. The optimum assembly is by hydrothermal reactions of Sn4+ salts and pre-reduced RGO (designated as RS nanocomposite). Raman spectra verified the fingerprint of RGO in the synthesized RS nanocomposite. The Sn3O4 planes of (111), (210), (130), ( 1¯3¯2) are observed from the X-ray diffractogram, and its average crystallite size is 3.94 nm. X-ray photoelectron spectroscopy on Sn3d and O1s spectra confirm the stoichiometry of Sn3O4 with Sn:O ratio = 0.76. Sn3O4-RGO-RS exhibits the highest response of 74% and 4% at 2 and 0.3 ppm, respectively. The sensitivity within sub-ppm CH3COOH is 64%/ppm. Its superior sensing performance is owing to the embedded and uniformly wrapped Sn3O4 nanoparticles on RGO sheets. This allows a massive relative change in electron concentration at the Sn3O4-RGO heterojunction during the on/off exposure of CH3COOH. Additionally, the operation is performed at room temperature, possesses good repeatability, and consumes only ~4 µW, and is a step closer to the development of a commercial CH3COOH sensor.

A Polyvinylpyrrolidone Nanofibrous Sensor Doubly Decorated with Mesoporous Graphene to Selectively Detect Acetic Acid Vapors

“…However, they may encounter limitations related to sensitivity, selectivity, response time, susceptibility to environmental interference, and sensing material stability. To address these limitations, as elucidated in the Introduction paragraph, integrating graphene (RGO or G) with metals [32] or ceramics [33] has enabled chemiresistors to operate effectively at room temperature, achieving remarkable sensitivity with detection limits of up to 1 ppb [34].…”

“…Conversely, sensors based on GQDs-ZnO composites (GQDs: graphene quantum dots) could be operated at room temperature and exhibited a stronger response to acetic acid gas compared to a pure ZnO sensor, detecting up to 1 ppm at room temperature [30]. The mesoporosity of a metal oxide (CuO) was utilized to create a sensor operating at 200 • C [31], whereas the incorporation of graphene (RGO or G) in conjunction with metals [32] or ceramics [33] enabled chemiresistors to function at room temperature with exceptional sensitivity (achieving a limit of detection of up to 1 ppb [34]). Avossa et al (2018) reported that a chemiresistor based on ES nanofibers of a blend of polystyrene and polyhydroxybutyrate (PS-PHB) hosting MGC (0.93% mass ratio) was sensitive and selective to acetic acid vapors, but only worked at a temperature slightly higher than room temperature (T = 40 • C).…”