Hydrothermal syntheses and gas sensing properties of cubic and quasi-cubic Zn 2SnO 4

Abstract

Zinc stannates (Zn 2SnO 4) with different morphologies and crystal structures were synthesized via low-temperature hydrothermal method in the presence of various alkaline mineralizers. Zn 2SnO 4 generally crystallizes into an inverse spinel crystal structure (cubic phase). However, we found that Zn 2SnO 4 could assembly into a slightly distorted cubic structure (quasi-cubic phase) for the first time by using tetrabutylammonium hydroxide as an alkaline mineralizer. In addition, we successfully tuned the morphologies of the as-prepared Zn 2SnO 4 particles, from cube, cuboctahedron, truncated octahedron, to octahedron, by adjusting the type and the concentration of alkaline mineralizers and surfactants. Compared with cubic Zn 2SnO 4, the quasi-cubic Zn 2SnO 4 showed a noticeable red shift of the band gap, and the gas sensors based on quasi-cubic Zn 2SnO 4 exhibited high sensitive performance to alcohol. XPS analyses revealed that the shift of Zn 2p 3/2 binding energy in the quasi-cubic Zn 2SnO 4, which indicated some Zn ions in quasi-cubic Zn 2SnO 4 adopted different coordination environments from regular tetrahedral/octahedral ones adopted in cubic Zn 2SnO 4.