Highly Sensitive Sub-ppm CHCOOH Detection by Improved Assembly of SnO-RGO Nanocomposite.

Detection of sub-ppm acetic acid (CHCOOH) is in demand for environmental gas monitoring. In this article, we propose a CHCOOH gas sensor based on SnO and reduced graphene oxide (RGO), where the assembly of SnO-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 Sn salts and pre-reduced RGO (designated as RS nanocomposite). Raman spectra verified the fingerprint of RGO in the synthesized RS nanocomposite. The SnO planes of (111), (210), (130), (13¯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 SnO with Sn:O ratio = 0.76. SnO-RGO-RS exhibits the highest response of 74% and 4% at 2 and 0.3 ppm, respectively. The sensitivity within sub-ppm CHCOOH is 64%/ppm. Its superior sensing performance is owing to the embedded and uniformly wrapped SnO nanoparticles on RGO sheets. This allows a massive relative change in electron concentration at the SnO-RGO heterojunction during the on/off exposure of CHCOOH. 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 CHCOOH sensor.