Scalable Fabrication of Cataluminescent Sensing Films with Enhanced Selectivity for Iso -Butanol over Structural Isomers

The broad use of gas sensors requires high selectivity and sensitivity together with scalable, reproducible fabrication of sensing films. Here, we report a slurry blade-coating route to thick-film MgO, SiO 2, and MgO–SiO 2 composite cataluminescence (CTL) sensing layers with controlled thickness and consistent performance. The MgO–SiO 2 composite exhibited enhanced markedly selectivity for iso -butanol (IBA) over its structural isomers, while maintaining rapid and reversible response characteristics. The calibration was linear from 15 to 580 mg/m 3, with a detection limit of 8.4 mg/m 3 ( S / N = 3). Practical applicability was demonstrated by online monitoring of IBA production during Saccharomyces cerevisiae fermentation, where the sensor outputs closely matched gas chromatography–mass spectrometry measurements. Mechanistic investigations revealed that acid–base bifunctional ensembles formed at interfacial Mg–O–Si domains can moderate the surface basicity of MgO, tune adsorption energetics, and redirect the oxidation pathway, which potentially contribute to the observed enhancement in selectivity. This work pioneers a scalable route to high-performance CTL sensor fabrication and provides molecular-level insights into selective gas sensing, paving the way for next-generation sensors tailored for complex environments.