Tuning Gas Sensor Selectivity via Morphological Engineering of Au Catalysts on TiO₂-based Nanosheets

Recent studies on catalyst development have primarily focused on discovering novel catalyst compositions, rather than exploiting the morphology and interface effects of existing catalytic materials. This study develops a novel material-driven gas sensor selectivity strategy by tailoring the surface energy of TiO_{2- y} (TO) and Ti_{1- x}Pt_xO_{2- y} (TPO) nanosheet (NS) supports to control the morphology of decorated Au catalysts. Through precise modulation of the substrate surface energies of TO/TPO NSs, the sizes and shapes of the Au catalysts can be engineered from nanoparticles (NPs) to micro-sized sheets without significant changes in chemical composition. This morphological control enables the realization of molecular weight-dependent gas selectivity, achieving enhanced detection of target gases, such as CO₂, ethanol, benzene, and toluene, with molecular weights of 40 or higher. In contrast to conventional approaches reliant on passive material properties, this strategy leverages engineered material interfaces and catalyst morphologies to actively direct gas sensing behavior. Furthermore, these results overturn the conventional notion that smaller catalysts necessarily yield higher reactivity, demonstrating that catalyst size and shape, governed by substrate-material interactions, can be key determinants of chemical reactivity. This finding provides a new pathway for the rational design of selective gas sensors through advanced materials engineering.