Hierarchical nanostructured WO3–SnO2 for selective sensing of volatile organic compounds

Abstract

It remains a challenge to find a suitable gas sensing material that shows a high response and shows selectivity towards various gases simultaneously. Here, we report a mixed metal oxide WO₃–SnO₂ nanostructured material synthesized in situ by a simple, single-step, one-pot hydrothermal method at 200 °C in 12 h, and demonstrate its superior sensing behavior towards volatile organic compounds (VOCs) such as ammonia, ethanol and acetone. SnO₂ nanoparticles with controlled size and density were uniformly grown on WO₃ nanoplates by varying the tin precursor. The density of the SnO₂ nanoparticles on the WO₃ nanoplates plays a crucial role in the VOC selectivity. The responses of the present mixed metal oxides are found to be much higher than the previously reported results based on single/mixed oxides and noble metal-doped oxides. In addition, the VOC selectivity is found to be highly temperature-dependent, with optimum performance obtained at 200 °C, 300 °C and 350 °C for ammonia, ethanol and acetone, respectively. The present results on the cost-effective noble metal-free WO₃–SnO₂ sensor could find potential application in human breath analysis by non-invasive detection.