Enhanced cataluminescence sensing of iso-butyraldehyde via phase-specific oxygen vacancies engineering in BaTiO3

Understanding the relationship between oxygen vacancies (V_OS) and gas sensing performance is pivotal for advancing high-performance gas sensors. In this study, we synthesized two cubic phase barium titanate (BaTiO₃) samples (BTO-1 and BTO-2) and one tetragonal phase BaTiO₃ sample (BTO-3). BTO-1 was subjected to additional nitrogen calcination to enhance its V_O concentration, while BTO-2 was prepared without this calcination step. Morphological and structural analyses confirmed that BTO-1 possesses the highest V_O concentration and surface-adsorbed oxygen content. Gas sensing investigations revealed that all BaTiO₃ samples exhibit excellent cataluminescence specificity toward iso-butyraldehyde (IBD), with response sensitivity that is strongly correlated to V_O concentration. Notably, BTO-1 demonstrated the highest sensitivity, achieving a detection limit of 7.3 mg/m³. Density functional theory calculations showed that cubic BaTiO₃ more readily forms V_O compared to its tetragonal counterpart, and the introduction of V_O enhances the adsorption and activation of both oxygen and IBD molecules. Reaction pathway analyses indicated that the primary oxidative decomposition of IBD on BaTiO₃ surfaces produces formic acid and acetone, with triplet acetone likely serving as the luminescent intermediate. These findings emphasize the significance of crystal phase-dependent V_O engineering in enhancing sensor performance and establish BaTiO₃-based materials as promising candidates for precise IBD detection. This work provides critical insights into designing next-generation gas sensors with tailored V_O properties for environmental and industrial applications.