Effect of Zn and Mo concentration in nanostructured ZnMoO4 synthesized by the hydrothermal method on the detection of acetone

abstract

This research investigates the gas-sensing behavior of nanostructured ZnO, MoO3, and ZnMoO4-based materials synthesized via the hydrothermal method at 140 °C for 10 h. Structural analysis using X-ray diffraction (XRD) reveals the formation of ZnO with a wurtzite structure in the Zn-100 sample, while the incorporation of Mo leads to the formation of ¿-ZnMoO4 and Zn3Mo2O9 phases in the Zn-75, Zn-50, and Zn-25 samples. Scanning electron microscopy (SEM) shows a transition from ZnO nanorods in Zn-100 to well-defined nanoplate morphology in Zn-50, which is optimal for gas interaction. Energy-dispersive X-ray spectroscopy (EDS) confirms elemental homogeneity in all samples. Fourier-transform infrared spectroscopy (FTIR) identifies Zn¿O and Mo¿O vibrational bands, while X-ray photoelectron spectroscopy (XPS) reveals a higher concentration of surface oxygen and the presence of structural defects in ZnMoO4-based samples, particularly Zn-50. Gas-sensing tests conducted at an optimal temperature of 300 °C with 200,000 ppm of acetone show that the Zn-50 sample achieves a maximum response of 92.88 %, outperforming ZnO and MoO3. This superior performance is attributed to the predominant Zn3Mo2O9 phase and enhanced structural disorder, which increase the number of active adsorption sites. In contrast, the Mo-100 sample exhibits negligible response due to low surface oxygen and the intrinsic limitations of MoO3 as a gas-sensing material. These findings highlight the critical role of precursor concentration in tuning the structural, morphological, and chemical properties of ZnMoO4-based sensors and demonstrate their potential for high-capacity, stable acetone detection in industrial and environmental monitoring applications. © 2025 Elsevier B.V.