Tuning Gas Sensing Properties through Metal-Nanocluster Functionalization of 3D SnO₂ Nanotube Arrays for Selective Gas Detection

The demand for highly sensitive and selective gas sensors for the detection of target gases in complex environments is rapidly increasing. In this study, we present a novel approach utilizing atomic layer deposition (ALD) technology to fabricate gas sensors based on metal-nanocluster functionalized 3D SnO₂ nanotube arrays. Pd/Au-nanocluster-sensitized SnO₂ sensors exhibit high sensitivity to formaldehyde, toluene, and acetone at room temperature, with detection limits of 1.2, 0.75, and 2.9 ppb, respectively. The selectivity of these sensors is due to the catalytic effect of metal nanoclusters on the SnO₂ surface, which changes the density of states near the Fermi level and influences gas adsorption and electronic transfer. The interactions between gas molecules and the Pd or Au nanoclusters are explored through theoretical calculations, revealing the role of metal atom d-orbitals in enhancing the gas-sensing performance. Furthermore, by incorporating the metal-nanocluster decorated sensors into a sensor array and employing a pattern recognition algorithm, we achieve successful discrimination of the target gases in real-time. This study offers a promising method for selectively detecting low-concentration gases in various complex environments.