The template-free synthesis of square-shaped SnO₂nanowires: the temperature effect and acetone gas sensors

Abstract

Square-shaped single-crystalline SnO(2) nanowires and their sphere-like hierarchical structures were synthesized successfully with a template-free hydrothermal approach. It was found that an intermediate phase-Na(2)Sn(OH)(6)-is first produced because it is slow to dissolve in ethanol/water media. The intermediate phase gradually decomposes and converts into SnO(2) at temperatures higher than 200 °C. The reaction temperature also affects the microstructure of SnO(2) nanomaterials. Uniform square-shaped SnO(2) nanowires, which form sphere-like hierarchical structures in 100% structure yield, can be produced at 285 °C on a large scale. The diameter of the nanowires shows a decrease accompanying the increase of the reaction temperature. The temperature effect could be a result of the faster and oriented growth of SnO(2) nanowires along their [Formula: see text] direction at higher temperature. Chemical sensors constructed with square-shaped SnO(2) nanowires exhibit excellent stability, good sensitivity and selectivity, as well as a quick response and short recovery times under exposure to acetone gas in practical applications.

Synthesis of hierarchical SnO2 nanoflowers with enhanced acetic acid gas sensing properties

“…6. The complex precursor Sn(OH) 4 2− anions are formed from the Sn 2+ of SnCl 2 and the OH − of NH 3 ·H 2 O under the hydrothermal according to reaction (1), and then the SnO 2 nanocrystal is formed from the hydrolysis of Sn(OH) 4 2− according to reaction (2). When the Na 3 C 6 H 5 O 7 is introduced into the SnCl 2 solution, due to the chelating between Sn 2+ and sodium citrate, Sn 2+ ions are partly precipitated into Sn(OH) 2 [35].…”

“…As we all know, changing texture, size and morphology of the materials can impact its physicochemical properties [1][2][3][4][5]. Therefore, the nanoscale assemblies, including nanoparticles [6], nanotubes [7], nanorods [8], nanosheets [9], nanocones [10] and hollow microspheres [11] are widely studied due to their various properties and potential applications [12][13][14][15][16][17][18].…”

Hydrothermal Synthesis of a CaNb2O6 Hierarchical Micro/Nanostructure and Its Enhanced Photocatalytic Activity

“…[1][2][3][4] Research on hierarchical structures provides potential applications in the bottom-up fabrication of advanced functional devices, including sensors, [5,6] fuel cells, [7] and photocatalysts. [8][9][10] The photocatalytic superiority of the hierarchical micro/ nanostructures can be attributed to their special structural features.…”

“…The corresponding optical absorption and photocatalytic activities of CaNb 2 O 6 samples with different morphologies were also studied. We used a soluble and active Nb V precursor which is prepared by a relatively simple and convenient hydrothermal treatment of Nb 2 [30,32] Since the hexaniobate ion [Nb 6 O 19 ] 8-has been known as the dominant species in alkaline solutions [41,42] and the solution of [Nb 6 O 19 ] 8-could be obtained by hydrothermal process, [43,44] we chose the alkali salt of [Nb 6 O 19 ] 8-as the water-soluble precursor for the synthesis of CaNb 2 O 6 . Additionally, it has been mentioned above that the pH value of the solution as well as the niobium oxide concentration determines the specific niobium ionic species present in aqueous solution, [45] tions of pH = 3.65-6.5.…”

Soft template synthesis of high selectivity mesoporous SnO2 gas sensors

“…It is well known that the sensing mechanism of SnO 2 is the surface controlled type. The response based on the reaction between adsorbed oxygen species on the surface of SnO 2 materials and the gas molecules may be detected [11][12][13] . Hence, the synthesis of thermally stable mesoporous SnO 2 with high surface areas is of great importance.…”