Gas sensing properties of individual SnO₂ nanowires and SnO₂ sol–gel nanocomposites

Abstract

This work is an investigation of the properties of semiconductor materials based on metal oxides, their catalytic properties, and their application as gas sensors, which were shown to exhibit high sensitivity, stability, and selectivity to target gases. The aim of this work is the comparison of gas sensing properties of tin dioxide in the form of individual nanowires and nanopowders obtained by sol–gel synthesis. This comparison is necessary because the traditional synthesis procedures of small particle, metal oxide materials seem to be approaching their limit. Because of this, there is increasing interest in the fabrication of functional materials based on nanowires, i.e., quasi-one-dimensional objects. In this work, nanocrystalline tin dioxide samples with different morphology were synthesized. The gas-transport method was used for the fabrication of well-faceted wire-like crystals with diameters ranging between 15–100 nm. The sol–gel method allowed us to obtain fragile gels from powders with grain sizes of about 5 nm. By means of X-ray photoelectron spectroscopy (XPS) it was proven that the nanowires contain considerably smaller amounts of hydroxy groups compared to the nanopowders. This leads to a decrease in the parasitic sensitivity of the sensing materials to humidity. In addition, we demonstrated that the nanowires are characterized by a nearly single-crystalline structure, ensuring higher stability of the sensor response due to the unlikelihood of sample recrystallization. The results from the ammonia detection experiments showed that the ratio of the sensor response to the surface area exhibits similar values for both the individual nanowire and nanopowders-based sensor materials.

Review: Influences of Semiconductor Metal Oxide Properties on Gas Sensing Characteristics

“…The most common methods of obtaining 1D SnO 2 nanostructures reported in the literature include the solvo/hydrothermal synthesis (Hien et al, 2011;Tan et al, 2011;Sial et al, 2017), chemical vapor deposition (Müller et al, 2012;Sayago et al, 2015;Stuckert et al, 2016;Shaposhnik et al, 2019), thermal evaporation (Shen et al, 2009;Thong et al, 2010;El-Maghraby et al, 2013), and sol-gel method (Li et al, 2017).…”

Tracking Structure and Composition Changes in Oxide Derived Cu-Sn Catalysts During CO2 Electroreduction Using X-Ray Spectroscopy

“…[42][43][44] For CuNW-SnHIGH (which are coated by approximately 20 nm ALD SnO2) the Cu Ledge region is completely featureless due to blocking of Cu photoelectrons by the SnO2 overlayer, providing evidence of both the surface sensitivity of the method and of the conformal nature of the ALD SnO2 film. The Sn M-edge spectra (Figure 4b) of as-synthesized CuNW-SnLOW and CuNW-SnHIGH display signals in the expected positions for the main peaks in SnO (487.9 eV and 495.5 eV) 45,46 and SnO2 (~492 eV and ~500 eV). 45,46 The spectra best resemble the SnO reference; however, the SnO reference spectrum is likely to display a mixture of SnO and SnO2 features due to surface oxidation during handling in air (see ESI S.3.2 and Figure S11).…”

“…The Sn M-edge spectra (Figure 4b) of as-synthesized CuNW-SnLOW and CuNW-SnHIGH display signals in the expected positions for the main peaks in SnO (487.9 eV and 495.5 eV) 45,46 and SnO2 (~492 eV and ~500 eV). 45,46 The spectra best resemble the SnO reference; however, the SnO reference spectrum is likely to display a mixture of SnO and SnO2 features due to surface oxidation during handling in air (see ESI S.3.2 and Figure S11). On the other hand, CuNW-Sn samples composed of SnO2 ALD layers, as confirmed by Sn 3d XPS spectra (vide infra), can display SnO features due radiation induced (partial) reduction of SnO2 layer.…”

Current Trends in Nanomaterials for Metal Oxide-Based Conductometric Gas Sensors: Advantages and Limitations. Part 1: 1D and 2D Nanostructures

“… ( a ) SEM image of SnO 2 nanowires after the synthesis using the gas transport method based on the vapor-liquid-solid (VLS) mechanism, and ( b ) SEM image of a single SnO 2 nanowire. Reproduced from Shaposhnik et al [ 292 ]. Published by Beilstein Sci.…”