Structure–Activity Relationship in UV-Driven Gas-Phase VOC Degradation Over Nanostructured SrTiO3 Photocatalysts

Strontium titanate (SrTiO3, STO) is a thermally perovskite semiconductor with growing potential in heterogeneous photocatalysis, yet its structure–activity relationships in gas-phase VOC degradation remain insufficiently understood. This study investigates how structural and morphological properties influence STO's photocatalytic performance toward different volatile organic compounds. Three STO samples were examined: two commercial powders (micro- and nanosized) and a nanostructured material synthesized via a sol–gel method and calcined at 900°C (STO@900). Ethanol, acetone, and propionic acid were used as model pollutants, with TiO2 as a benchmark. Characterization revealed that STO@900 possesses high phase purity, nanometric crystallite size, and a hierarchical meso–macroporous structure, enhancing surface accessibility, and charge transport. Photocatalytic tests showed that performance depends strongly on both catalyst properties and pollutant type. STO@900 achieved high degradation efficiency for ethanol and propionic acid, comparable to TiO2, while all STO samples showed limited activity toward acetone. Mechanistic insights were obtained by monitoring acetaldehyde formation, highlighting different reaction pathways on STO and TiO2. Overall, the results demonstrate that synthesis-controlled structural features critically determine STO photocatalytic behavior, offering guidance for designing efficient perovskite-based materials for air purification applications.