Defect-rich ultrathin Sn2O3 nanosheets with dominant polar (100) facets for efficient gas and humidity sensor applications.

Defect-rich ultrathin heterovalent tin oxide (Sn 2 O 3) nanosheets with dominant polar (100) facets were synthesized via a facile hydrothermal method for the first time. The structure, morphology, chemical state, bandgap, defects, and specific surface area of these Sn 2 O 3 nanosheets were characterized by XRD, FE-SEM, TEM, XPS, UV–Vis, PL, N 2 -adsorption, respectively. Taking inspiration from the morphology, defects, and exposed facets that facilitate adsorption-interaction of molecules on the surface, gas and humidity sensors were fabricated based on Sn 2 O 3 nanosheets. The gas sensor response to 200 ppm ethanol at 200 °C is as high as 70.1, and response and recovery times are only 6 s and 3 s, respectively. At room temperature, the humidity sensor exhibits a response up to 2.76 × 103 with a small humidity hysteresis of 1.95%, and the response and recovery times are divided into 27 s and 124 s, respectively. Additionally, both gas and humidity sensors demonstrate excellent repeatability and stability. Finally, gas and humidity sensing mechanisms of the Sn 2 O 3 sensor have been discussed. This work provides a practical candidate for gas and humidity sensors and further develops a new promising application for heterovalent metal oxides in electrical sensory devices. In this contribution, defect-rich ultrathin Sn 2 O 3 nanosheets with dominant polar (100) facets are synthesized via a hydrothermal method for the first time that can be used as an attractive bifunctional sensing material. The enhanced gas and humidity response are mainly attributed to the ultrathin nanosheet morphology, large specific surface area, abundant intrinsic surface defects, and dominant polar (100) facets. [Display omitted] • Defect-rich ultrathin Sn 2 O 3 nanosheets with dominant polar (100) facets are synthesized for the first time. • Sn 2 O 3 nanosheets exhibit excellent gas sensing properties to 5-800 ppm ethanol at 200 °C. • Sn 2 O 3 nanosheets also show wonderful humidity sensing performance under different relative humidity at room temperature. • Enhanced gas/humidity response is attributed to the unique morphology, abundant defects, and dominant (100) facets. [ABSTRACT FROM AUTHOR]