Organometallic-derived metal oxide sensors for H₂S detection in an electronic nose for odor abatement assessment

Abstract

We present the development and application of novel metal oxide gas sensors derived from organometallic and ion-exchange synthesis routes, integrated into an electronic nose platform for the detection of hydrogen sulfide (H₂S) and odorous compounds. The CuO, SnO₂, and WO₃ nanoparticles were characterized using transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). These nanomaterials were deposited as single and double-layer structures forming engineered p–n and n–n heterojunctions. The sensors were evaluated in a wide H₂S concentration range (5 ppb to 50 ppm) under controlled humidity and temperature conditions. Double-layer configurations exhibited significantly enhanced sensitivity, selectivity, and stability compared to commercial MOS sensors. Selected sensors were integrated into a custom-built gas sensing array and used to construct an e-nose system. The system was trained using dynamic olfactometry and applied for odor quantification in real samples from a Municipal Solid Waste Treatment Plant (MSWTP). The e-nose achieved high accuracy in estimating odor concentrations and deodorization efficiency in two full-scale biofilters, outperforming commercial sensor systems. This study presents a complete sensor-to-application workflow, combining nanomaterial design, sensor engineering, statistical modelling, and real-world environmental monitoring. It highlights the potential of organometallic-derived MOS sensors as key components in advanced gas sensing platforms for reliable odor detection in complex industrial environments.