Highly Sensitive Sub-ppm CH 3 COOH Detection by Improved Assembly of Sn 3 O 4 -RGO Nanocomposite.

Detection of sub-ppm acetic acid (CH ₃ COOH) is in demand for environmental gas monitoring. In this article, we propose a CH ₃ COOH gas sensor based on Sn ₃ O ₄ and reduced graphene oxide (RGO), where the assembly of Sn ₃ O ₄ -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 ⁴⁺ salts and pre-reduced RGO (designated as RS nanocomposite). Raman spectra verified the fingerprint of RGO in the synthesized RS nanocomposite. The Sn ₃ O ₄ 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 Sn ₃ O ₄ with Sn:O ratio = 0.76. Sn ₃ O ₄ -RGO-RS exhibits the highest response of 74% and 4% at 2 and 0.3 ppm, respectively. The sensitivity within sub-ppm CH ₃ COOH is 64%/ppm. Its superior sensing performance is owing to the embedded and uniformly wrapped Sn ₃ O ₄ nanoparticles on RGO sheets. This allows a massive relative change in electron concentration at the Sn ₃ O ₄ -RGO heterojunction during the on/off exposure of CH ₃ COOH. 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 CH ₃ COOH sensor.