Enhanced formaldehyde sensing properties of SnO2 nanorods coupled with Zn2SnO4

Abstract

Ternary oxide Zn₂SnO₄ was introduced to a rod-like nanostructured SnO₂ gas sensor for formaldehyde detection by a facile one-step hydrothermal synthesis. The effects of the Zn₂SnO₄ additive on the structure, morphology and gas-sensing property of SnO₂ were investigated in this study. It was confirmed that control of the Zn amounts in the precursor solution was effective in realizing well-developed one- and two-dimensional coexisting structured SnO₂–Zn₂SnO₄ (SnZn) nanocomposites. The gas sensing properties of the resulting SnZn composites to HCHO vapor were tested. The results showed that the presence of Zn₂SnO₄ species in SnO₂ powders could effectively enhance electrical conductivity, reduce optimal operating temperature and improve the gas response of the sensors. The composite exhibited the highest response towards HCHO in the case of 35 at% Zn₂SnO₄ nanoplates coupling with hierarchical branched structures of SnO₂ nanorods (SnZn₃₅) at a relatively lower operating temperature of 162 °C. The good gas-sensing performance of the SnZn₃₅ composite can be ascribed to the smaller particle size, the larger surface area and the more absorbed O_x⁻ species, which all are favorable for gas diffusion and sensing reactions. This work renders great potential in the fabrication of gas sensors using a binary–ternary oxide composite, which can be further applied in indoor pollution detection.