An efficient and controllable ultrasonic-assisted microwave route for flower-like Ta(V)–MOF nanostructures: preparation, fractional factorial design, DFT calculations, and high-performance N2 adsorption

Abstract

With respect to different applications of metal–organic framework (MOF) in the medical, industrial and environmental fields, it is very important to choose a new structure that can be synthesized by fast, eco-friendly and affordable methods with distinctive properties so that the properties could be systematically controlled. In this study, new Ta–MOF nanostructures are synthesized by novel methods of microwave (Mw) and ultrasonic assisted microwave (UAMw) in environmental conditions. The final products are characterized by relevant techniques. Although in the both methods, the synthesized products have favourable properties; the use of the UAMw method would produce samples with distinct features such as high thermal stability of 240 °C, average particle size distribution (PSD) of 23 nm and significant specific surface area (SSA) of 2012 m2/g. For a better comprehension of the Ta–MOF formation, computational studies are performed using DFT calculations. In order to investigate the effect of the synthesis parameters on different features of the products, the fractional factorial design is used. The results of analysis of variance confirm that the parameters such as Mw power, Mw duration, ultrasonic temperature, ultrasonic power and ultrasonic duration have a significant effect on PSD and SSA of Ta–MOF samples. Due to the fractional factorial design of the experiments, response surface methodology would optimize the probability of producing samples with the small PSD of 15 nm and high SSA of 2588 m2/g; this desirable amount would provide situations to use these compounds in diverse fields.