Morphology-Controllable Synthesis and Characterization of Single-Crystal Molybdenum Trioxide

Abstract

Molybdenum trioxide nanobelts and prism-like particles with good crystallinity and high surface areas have been prepared by a facile hydrothermal method, and the morphology could be controlled by using different inorganic salts, such as KNO3, Ca(NO3)2 , La(NO3)3, etc. The possible growth mechanism of molybdenum trioxide prism-like particles is discussed on the basis of the presence of H+ and the modification of metal cations. The as-prepared nanomaterials are characterized by means of powder X-ray diffraction (PXRD), field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), Fourier transformation infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and ultraviolet and visible spectroscopy (UV-vis). TEM and HRTEM micrographs show that the molybdenum trioxide nanobelts and prism-like particles have a relatively high degree of crystallinity and uniformity. BET specific surface areas of the as-prepared molybdenum trioxide nanocrystals are 67-79 m2 g-1. XPS analysis indicates that the hexavalent molybdenum is predominant in the nanocrystals. UV-vis spectra reveal that the direct band gap energy of the annealed molybdenum trioxide prism-like particles shows a pronounced blue shift compared to that of bulk MoO3 powder. Interestingly, molybdenum trioxide nanobelts exhibit a red shift under this condition.

Performance of 3%Mo/ZSM-5 catalyst in the presence of water during methane aromatization in supersonic jet expansion

“…For the as-prepared catalyst, the molybdenum species on the surface of HZSM-5 exist mainly as molybdenum oxide. One can see that the Mo 3d 5/2 (B.E ¼ 232.7 eV) and Mo 3d 3/2 (B.E ¼ 235.6 eV) peaks of fresh catalyst can be attributed to Mo 6þ (MoO 3 ) species ( Figure 9a), a kind similar to that of Mo (VI) reported by Xia et al 26 The result is in agreement with the picture depicted by Tessonnier et al 27 that during catalyst synthesis, the MoO 3 crystallites first dispersed on HZSM-5 and then 95 Mo NMR technique, Zheng et al 20 confirmed that there were exchanged Mo species on the zeolite framework. The result of pure CH 4 collected under SJE condition (Figure 9b) differs from those collected under normal condition where MoO 3 species on the surface and/or in the channels of HZSM-5 are completely converted to Mo 2 C. 8,30 This is understandable because in the former case, there is a fast diffusion of methane towards the region of low pressure, and the extent of reduction of catalyst by CH 4 is less effective.…”

Systematic study on the influence of the morphology of α-MoO3 in the selective oxidation of propylene

“…The method is, however, particularly attractive for (mixed) molybdenum oxides, which have high potential as catalysts in the selective oxidation of hydrocarbons [17][18][19][20][21][22]. Various preparation routes are known for the hydrothermal synthesis of molybdenum trioxide in the shape of ribbons, rods or nanobelts [12,[23][24][25][26][27][28].…”

“…Furthermore, the crystal morphology can be altered by using different inorganic salts like NaNO3 and KNO3 in the synthesis solution [23,24]. However, they have been hardly tested in catalysis and the use of inorganic salts or hydrochloric acid may have a negative influence on the catalytic activity of the synthesized molybdenum oxides due to potential sodium, potassium, or chlorine residues in the product.…”

Rapid synthesis of free-standing MoO3/Graphene films by the microwave hydrothermal method as cathode for bendable lithium batteries

“…The There are several reports on the hydrothermal synthesis of MoO 3 nanostructures to produce materials with high purity, homogeneity, good crystallinity, and unique properties [20,[38][39][40]. Microwave irradiation can be used as an alternative heat source for the 5 hydrothermal process [41,42].…”