Hydrothermal Synthesis of Self-Assembled Hierarchical Tungsten Oxides Hollow Spheres and Their Gas Sensing Properties

Abstract

Hierarchical self-assembled hollow spheres (HS) of tungsten oxide nanosheets have been synthesized via a template-free hydrothermal method. Morphology evolution of the products is determined by the amount of H2C2O4 (oxalic acid) which serves as chelating agent. Structural features of the products were characterized by X-ray diffraction (XRD), and morphology was investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). In addition, the porous structure was analyzed using the Brunauer-Emmett-Teller (BET) approach. The synthesis mechanism of the products with self-assembled hierarchical structures was proposed. The NO2 gas sensing properties of self-assembled hierarchical WO3 HS materials were investigated, the gas sensing properties of WO3 synthesized by a variety of formulations were compared, and the possible gas sensing mechanism was discussed. The obvious enhancement of the gas sensing properties was ascribed to the structure of the hierarchical HS.

Hydrothermal preparation and supercapacitive performance of flower-like WO3·H2O/reduced graphene oxide composite

“…Under hydrothermal condition, tungsten acid precursors further, decompose and grow to form WO 3 ·H 2 O nanosheets and GO was reduced to rGO by oxalic acid. Afterwards, the WO 3 ·H 2 O nanosheets could experience a self-assmbly process to form WO 3 microflowers [11].…”

“…Tungsten trioxide (WO 3 ) and its hydrates (WO 3 ·xH 2 O, x = 0∼2), as one of the important transition metal oxides, are extensively investigated due to the promising properties and a wide spectrum of applications in gas sensors [11,12], photocatalysis [13,14], electrochromic devices [15,16], electronic devices [17], dye-sensitized solar cells [18,19], adsorbent [20] and lithium ion batteries [21,22]. The capacitive behaviors of the nanostructured tungsten oxides have been also investigated as supercapacitor electrodes [23][24][25][26][27][28][29].…”

A novel low temperature gas sensor based on Pt-decorated hierarchical 3D SnO2 nanocomposites

“…Furthermore, Fig. 1d is the corresponding HRTEM image of the support, and the clearly resolved lattice fringes are calculated to be around 0.333 nm, which can be indexed to the (110) plane of the 11 tetragonal SnO 2 phase [54].…”

“…Multiple nanomaterials based on semiconducting metal oxides have demonstrated attracting properties in magnetics [3], optics [4], electrocatalysts [5], photocatalysts [6], chemical sensors [7][8][9][10][11], lithium ion batteries [12], biomedical research [13,14], et. al.…”

Facile Synthesis of Cu/Cu2O Nanoparticles–Graphene Composites for Efficient Detection of NO2 at Room Temperature

“…To date, the most e®ective NO 2 sensing materials are semiconductor metal oxides such as In 2 O 3 , ZnO, SnO 2 , WO 3 , etc. [2][3][4][5] Amongst these metal oxides, copper oxide (Cu 2 O) which is an environmentally friendly p-type semiconductor with a direct bandgap of 2.0 eV, has been reported as a promising candidate for detecting NO 2 gas. 6 However, it is still important to improve the sensibility, detection limit and operation temperature of gas sensors.…”