Fabrication of SnO2–SnO nanocomposites with p–n heterojunctions for the low-temperature sensing of NO2 gas

Abstract

In this report, the fabrication of a novel SnO₂–SnO nanostructure with p–n heterojunctions has been achieved through a facile one-pot and low-cost hydrothermal process. The structure and properties of the nanocomposite were analyzed with X-ray techniques and electron microscopy. HRTEM characterization showed that the p–n heterojunctions were formed with small n-type SnO₂ nanocrystals dispersed on the surface of large p-type SnO crystals. Compared to the single SnO₂-based material, a gas sensor fabricated from the SnO₂–SnO composite exhibited an enhanced sensing performance for NO₂ gas detection, with a limit of detection and sensitivity of 0.1 ppm and 0.26 ppm⁻¹, respectively, at a relatively low operating temperature (50 °C). Moreover, the p–n heterojunctions exhibited high sensing selectivity for NO₂. Such a high sensing sensitivity and a low operating temperature make the SnO₂–SnO p–n nanomaterial a promising gas sensor for practical NO₂ gas detection. The improved sensing response characteristics of the hybrid material could be attributed to the p–n junctions formed through the in situ growth of SnO₂ nanocrystals on SnO nanoplates. The present study is helpful for the design of novel gas sensing materials and the development of NO₂ gas sensors.