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

TLDR

The reaction temperature influences the microstructure of SnO₂ nanomaterials. A template‑free hydrothermal method produced square‑shaped single‑crystalline SnO₂ nanowires and sphere‑like hierarchical structures, with higher temperatures accelerating oriented growth along the [Formula: see text] direction. The study shows that Na₂Sn(OH)₆ forms first and converts to SnO₂ above 200 °C, enabling uniform square‑shaped nanowires with 100 % yield at 285 °C, whose diameter shrinks with temperature, and that sensors made from these nanowires exhibit excellent stability, sensitivity, selectivity, and rapid response to acetone.

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.