Synergistic enhancement effect on surface Au nanoparticles decoration on Co-doped SnO2 nanobelts: High-response and selection for VOC gas sensing

Abstract

The surface of Au nanoparticles (NPs) modified materials can greatly improve the physical and chemical properties of materials. Herein, enabling excellent sensing performances via the decoration of Au NPs on 0.5 wt% Co-doped SnO₂ nanobelts (NBs) sensors is demonstrated. After decorating the content of Au NPs into three different ratios by controlling different sputtering times, denoted by Au-Co-SnO₂-1, Au-Co-SnO₂-1.5, and Au-Co-SnO₂-2, respectively. According to the characterization results, the Au-Co-SnO₂-1.5 based sensor exhibits the best gas sensing performances, for example, it achieves the highest response, which is nearly twenty times from 41 to 793, while the optimal operating temperature is reduced from 340 °C to 280 °C, and the response and recovery times have been reduced from 66 s to 63 s–44 s and 31 s in comparison with the pure SnO₂ based sensor for 50 ppm 1-butanol. The morphological and microstructural properties of these NBs were analyzed through X-ray diffraction (XRD), Raman spectroscopy, Scanning electron microscopy (SEM), Brunauer–Emmet–Teller (BET) nitrogen adsorption–desorption isotherms measurement and X-ray Photoelectron Spectroscopy (XPS). The XPS results show that the corresponding response magnitude is positively correlated with the proportion of adsorbed oxygen. On the basis of the investigation, the mechanism for enhanced gas sensing performances of Au-Co-SnO₂-1.5 based sensor can be primarily ascribed to the synergistic effect of increasing surface-active sites caused by oxygen vacancies, promoting the formation of additional adsorbed oxygen.