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

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), (13 over bar 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 similar to 4 mu W, and is a step closer to the development of a commercial CH3COOH sensor.