Tartaric acid-assisted synthesis and acetone gas sensing properties of hierarchical WO3 phase junctions

Acetone is a hazardous substance that can directly impact vital human organs. Accurate detection is crucial for ensuring air quality, monitoring the environment, and conducting medical diagnostics. Herein, hierarchical WO₃ phase junctions assembled with nanoparticals and nanosheets were synthesized by a simple tartaric acid-assisted hydrothermal method. The morphology, phase, and band gap of WO₃ are influenced by the use of different chiral tartaric acids (L(+)-tartaric acid, D(-)-tartaric acid, DL-tartaric acid). Compared with the sample prepared with L(+)-tartaric acid, D(-)-tartaric acid, hierarchical WO₃ phase junctions prepared with DL-tartaric acid have the higher exposed crystal faces, and the sensor with this structure shows the highest response (R_a/R_g = 162.3), short response/recovery time (16 s/15 s) to 50 ppm acetone, along with low practical detection limit (300 ppb) at the operating temperature of 180 °C. Additionally, it possesses favorable selectivity, satisfactory reproducibility, stability, and resistance to moisture. The reaction process of acetone is revealed using in situ diffuse reflectance infrared fourier transform spectroscopy (DRIFT) and validated through density functional theory (DFT) calculations. Such enhanced acetone sensing mechanism mainly roots from its unique structure, the narrow band gap, high exposed crystal faces, phase junctions and oxygen vacancies. This work provides a novel design method to construct hierarchical WO₃ phase junctions with high gas-sensing performance.