Combining microwave and ultrasound irradiation for rapid synthesis of nanowires: a case study on Pb(OH)Br

Abstract

BACKGROUND: One-dimensional (1D) nanostructures such as wires, tubes and belts have attracted much attention in recent years because of their fascinating properties and promising applications, and various methods have been developed to prepare 1D nanostructures. Microwave and ultrasound, two methodologies for rapid synthesis, have both been applied to fabricate nanostructures. This paper reports on combining microwave and ultrasound irradiation as a new strategy for rapid synthesis of nanowires. Using Pb(OH)Br as a study case, nanowires were rapidly synthesized under the combined irradiation. The use of the ionic liquid 1-butyl-3-methylimidazolium bromide as a structure-directing agent and microwave absorbent significantly simplified the preparation procedure.

Microwave–ultrasound assisted synthesis of β-FeOOH and its catalytic property in a photo-Fenton-like process

“…The kinetic constant for the MO degradation increases when the microwave power increases and/or the ultrasound power decreases. Under combined microwave and ultrasound radiation condition, the b-FeOOH nuclei form and grow quickly on the one hand due to rapidly changing electric field of the microwave irradiation, on the other hand, the microjets and shockwaves generated by the ultrasound radiation stir the reaction solution and reduce the agglomeration of nanoparticles to a certain extent [26,29]. Therefore, the interaction between microwave and ultrasound has important effect on the morphology and catalytic activity of the prepared b-FeOOH sample, although the mechanism of interaction is not clear now.…”

“…It can rapidly transfer energy directly to the reactants, and causes an internal and external temperature rise almost at the same time, in contrast with conventional conductive heating. This allows rapid decomposition of the precursors, thus creating highly supersaturated solutions where nucleation and growth can take place to produce the desired nanocrystalline products [26,27]. Ultrasonic process can bring about instantaneous generation, growth and collapse of micrometer-sized bubbles in liquid medium [28][29][30].…”

The Combined Use of Microwaves and Ultrasound: Methods and Practice

“…Combined MW-US irradiation (50 W each) was also instrumental in accelerating the preparation of Pb(OH)Br nanowires [73]. The process was conducted in an IL (1-butyl-3-methylimidazolium bromide) which acted as both a solvent and a structure-directing agent.…”

Microwave and Ultrasounds Together – A Challenge

“…In an apparatus similar with those described in figure 1, Shen [11] proposed a rapid synthesis of Pb(OH)Br nanowires. Heating alone provide 0.02 -0.03 mm diameter and 2 -3 mm length nanowires, while MW (50 W) the diameter is ten times smaller and rather short nanowires.…”

“…Combining MW and US (50 W -50 W) the diameter drops to 80 -800 nm, and the length to 50 -100 μm. If the MW power is higher -250 W, (higher heating contribution) and US power maintained the same, the diameter narrowed (100 -500 nm) while the length became rather short Table 1 in reference [11]). After 2010 a number of papers were published having as topic either two steps processes, like metal organic framework IRMOF-1 synthesis [12], (in a separate reactors as stated by Lionelli and Mason), synthesis of polysubstituted pyridines under combined microwave and ultrasound irradiation [13], porous manganese dioxide (MnO2) synthesized via an ultrasound-microwave-intensified precipitation [14] (perhaps in a single reactorthe papers do not offers details of equipment), or even for biodiesel preparation emphasizing the synergetic effects of combining both source of energy in one device [15].…”