Ultrasonic-assisted synthesis of highly dispersed MoO3 nanospheres using 3-mercaptopropyltrimethoxysilane

Nanostructured MoO3 for Efficient Energy and Environmental Catalysis

This paper mainly focuses on the application of nanostructured MoO₃ materials in both energy and environmental catalysis fields. MoO₃ has wide tunability in bandgap, a unique semiconducting structure, and multiple valence states. Due to the natural advantage, it can be used as a high-activity metal oxide catalyst, can serve as an excellent support material, and provide opportunities to replace noble metal catalysts, thus having broad application prospects in catalysis. Herein, we comprehensively summarize the crystal structure and properties of nanostructured MoO₃ and highlight the recent significant research advancements in energy and environmental catalysis. Several current challenges and perspective research directions based on nanostructured MoO₃ are also discussed.

An elevated concentration of MoS2 lowers the efficacy of liquid-phase exfoliation and triggers the production of MoOx nanoparticles

The oxidation of MoS₂ with a simultaneous decrease of MoS₂ content.

Solvothermal synthesis of ultrasmall tungsten oxide nanoparticles

The synthesis of catalytically useful, ultrasmall oxide nanoparticles (NPs) of group 5 and 6 metals is not readily achievable through reported methods. In this work, we introduce a one-pot, two-precursor synthesis route to <2 nm MO(x) NPs in which a polyoxometalate salt is decomposed thermally in a high-boiling organic solvent oleylamine. The use of ammonium metatungstate resulted in oleylamine-coated, crystalline WO(x) NPs at consistently high yields of 92 ± 5%. The semicrystalline NPs contained 20-36 WO(x) structural units per particle, as determined from aberration-corrected high-resolution scanning transmission electron microscopy, and an organic coating of 16-20 oleylamine molecules, as determined by thermogravimetric analysis. The NPs had a mean size of 1.6 ± 0.3 nm, as estimated from atomic force microscopy and small-angle X-ray scattering measurements. Carrying out the synthesis in the presence of organic oxidant trimethylamine N-oxide led to smaller WO(x) NPs (1.0 ± 0.4 nm), whereas the reductant 1,12-dodecanediol led to WO(x) nanorods (4 ± 1 nm × 20 ± 5 nm). These findings provide a new method to control the size and shape of transition metal oxide NPs, which will be especially useful in catalysis.

Ultrasonic-assisted preparation of metastable hexagonal MoO3 nanorods and their transformation to microbelts

Metastable hexagonal h-MoO(3) nanorods were synthesized by a simple sonochemical method, and then were transformed into thermodynamically stable a-MoO(3) microbelts by calcination. The obtained samples were characterized by X-ray diffraction (XRD), differential thermal analysis (DTA), field-emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). It was found that the as-prepared h-MoO(3) nanorods were of 0.2-1.2 μm in width and 1-6 μm in length. A possible formation and growth mechanism of hexagonal MoO(3) nanorods is proposed, in which ultrasound plays a crucial role and cannot be ignored. Moreover, the effect of temperature on the transformation process by calcination is investigated and a possible growth process of microbelts is also discussed.