Ultrasonic Spray Pyrolysis of Functional Zn─Sn─O Matrix Semiconductors: Stoichiometric Design for Enhanced Acetone Selectivity in VOC Sensing

Abstract Tin oxide (SnO 2 ), zinc oxide (ZnO), and zinc stannate (ZnSnO 3 , Zn 2 SnO 4 ) thin films are synthesized via ultrasonic spray pyrolysis, employing stoichiometric control to tailor Zn─Sn─O compositional matrices. Five samples are designed to transition from pure SnO 2 through intermediate Zinc stannate configurations (S25Z, S50Z, S75Z) to pure ZnO. Structural, morphological, and compositional analyses are performed using X‐ray diffraction (XRD), including Rietveld refinement, Fourier‐transform infrared spectroscopy (FTIR), X‐ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and energy‐dispersive spectroscopy (EDS). Qualitative and quantitative analysis confirms the formation of ZnSnO 3 and Zn 2 SnO 4 phases, along with additional Zn─Sn─O matrix compounds whose precise identification remains inconclusive. Acetone adsorption energy is calculated using DFT and compared with experimental results. Machine learning models (XGBoost regression) predict acetone sensing performance with high precision (MAE: 3.19, R 2 : 0.97), while SHAP analysis identifies key parameters influencing sensor response and stability. Acetone is used as the target analyte to evaluate sensing capabilities at 200 and 300 °C. Among the samples, the S50Z thin film exhibits the highest performance at 300 °C, with response/recovery times of 193/207 s, respectively, and a sensing response of 87%. These findings highlight Zn─Sn─O materials as promising candidates for selective VOC detection, with potential applications in medical diagnostics via breath analysis.