Single-crystalline MoO3 nanoplates: topochemical synthesis and enhanced ethanol-sensing performance

Abstract

Molybdate-based inorganic-organic hybrid disks with a highly ordered layered structure were synthesized via an acid-base reaction of white molybdic acid (MoO 3 $H 2 O) with n-octylamine (C 8 H 17 NH 2 ) in ethanol at room temperature. The thermal treatment of the as-obtained molybdatebased inorganic-organic hybrid disks at 550 C in air led to formation of orthorhombic a-MoO 3 nanoplates. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermal analysis (TG-DTA), Fourier-transform infrared (FT-IR) spectra, Raman spectra, and a laser-diffraction grain-size analyzer were used to characterize the starting materials, the intermediate hybrid precursors and the final a-MoO 3 nanoplates. The XRD, FT-IR and TG-DTA results suggested that the molybdate-based inorganic-organic hybrid compound, with a possible composition of (C 8 H 17 NH 3 ) 2 MoO 4 , was of a highly ordered lamellar structure with an interlayer distance of 2.306(1) nm, and the n-alkyl chains in the interlayer places took a double-layer arrangement with a tilt angle of 51 against the inorganic MoO 6 octahedra layers. The SEM images indicated that the molybdate-based inorganic-organic hybrids took on a well-dispersed disk-like morphology, which differed distinctly from the severely aggregated morphology of their starting MoO 3 $H 2 O powders. During the calcining process, the disk-like morphology of the hybrid compounds was well inherited into the orthorhombic a-MoO 3 nanocrystals, showing a definite plate-like shape. The a-MoO 3 nanoplates obtained were of a single-crystalline structure, with a side-length of 1-2 mm and a thickness of several nanometres, along a thickness direction of [010]. The above a-MoO 3 nanoplates were of a loose aggregating texture and high dispersibility. The chemical sensors derived from the as-obtained a-MoO 3 nanoplates showed an enhanced and selective gas-sensing performance towards ethanol vapors. The a-MoO 3 nanoplate sensors reached a high sensitivity of 44-58 for an 800 ppm ethanol vapor operating at 260-400 C, and their response times were less than 15 s.

Síntese, caracterização e aplicação do trióxido de molibdênio na fotocatálise de efluente têxtil sintético

“…7 e 8. Os picos intensos foram atribuídos à alta cristalinidade do material, sendo possível identificar os três principais picos (994, 818 e 290 cm -1 ) característicos da estrutura ortorrômbica em camadas [20,39,43]. Na Fig.…”

Tuning the interlayer of transition metal oxides for electrochemical energy storage

“…In a related experiment, Na 0.5 (H 2 O) y MoO 3 bronze was used to intercalate various organic compounds; interlayer spacings as large as 37.9 Å were reported for MoO 3 intercalated with tetradecylamine. 86 Chen et al 87 utilized MoO 3 ÁH 2 O as the precursor for the solvent exchange of water with n-octylamines in ethanol. The reaction was described as an acid-base reaction between the water molecules and amines.…”

Topochemical Conversion of Inorganic–Organic Hybrid Compounds into Low-Dimensional Inorganic Nanostructures with Smart Control in Crystal-Sizes and Shapes

“…This chapter deals with the synthesis of WO 3 and MoO 3 nanoplates using H 2 WO 4 , H 2 W 2 O 7 , and MoO 3 ·H 2 O solid powders as the starting materials. [1][2][3][4][5][6][7] The synthesis of carbides and nitrides of tungsten is also introduced using the as-obtained tungstate-based inorganic-organic hybrid compounds as precursors. [8,9] The applications of WO 3 and MoO 3 nanoplates in sensors are also introduced.…”

“…14d shows a typical HRTEM image of the edge of the WO 3 nanoplate. [7] 4.1 Material synthesis and characterization MoO 3 H 2 O powders reacted with n-octylamine at room temperature to form molybdatebased inorganic-organic hybrid compounds. Typically, 10.3 mL of n-octylamine was firstly mixed with 113.7 mL of ethanol in a conical flask under magnetic stirring, and then 5.0 g of MoO 3 H 2 O powders was dispersed into the above mixture to form a white suspension.…”

“…[6,10,11] The related mechanisms are discussed in some details. [1][2][3][4][5][6][7][8][9][10][11] [1][2][3][4] …”