THERMODYNAMIC MODELING OF THE PROCESSES OF MOLECULAR LAYERING OF MoO3 ON β-CRISTOBALITE AND MONOLAYERS OF MoOX AND AlOX BY THE DFT METHOD: COMPARATIVE EVALUATION OF THE REACTIONS OF MoOCl4 AND MoO2Cl2 WITH H2O

In this work, quantum chemical modeling was applied to study the surface reactions of molecular layering of molybdenum (VI) oxide on the surface of β-cristobalite and amorphous monolayers of MoOx and AlOx on β-cristobalite using gaseous MoOCl4, MoO2Cl2, and H2O as reagents. Using the generalized gradient approximation method of density functional theory, the Gibbs energy changes of the molecular layering reactions (ΔG°) in the temperature range from 273.15 to 650.15 K were calculated. The calculations were carried out considering the aggregate state of the reacting substances — in the approximation of an ideal gas for gaseous substances and excluding the translational and rotational contributions for the solid phase components. According to the obtained data, the highest reactivity of the surface of the amorphous aluminum oxide monolayer on β-cristobalite is predicted in the considered temperature range. Additionally, it was found that the MoOCl4 compound has greater chemical activity compared to MoO2Cl2 towards the studied substrates. An explanation is provided for the absence of molybdenum oxide structure growth on the surface of β-cristobalite and the possible reasons for the higher reactivity of the aluminum oxide monolayer compared to the β-cristobalite surface and the amorphous MoOx monolayer. Our computational approach can generally aid in understanding the fundamental aspects of nucleation and growth of MoO3 films and mixed oxide materials like AlxMoyOz on various surfaces. Additionally, the vibrational mode frequencies in molybdenum-containing structures on the substrate surfaces were calculated in the anharmonic approximation: vSi-O-Mo = 901-1002 cm⁻1, vAl-O-Mo = 921-1015 cm⁻1, vMo-O-Mo = 716-889 cm⁻1, vMo=O = 972-1010 cm⁻1. For citation: Gadjimuradov S.G., Suleymanov S.I., Maksumova A.M., Drozdov Ye.O., Abdulagatov I.M., Abdulagatov A.I. Thermodynamic modeling of the processes of molecular layering of MoO3 on β-cristobalite and monolayers of MoOx and AlOx by the DFT method: comparative evaluation of the reactions of MoOCl4 and MoO2Cl2 with H2O. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2025. V. 68. N 3. P. 50-63. DOI: 10.6060/ivkkt.20256803.7132.