Decoration of Gold Nanoparticles on TiO₂ Thin Films for Enhanced Response of Ethanol Gas Sensors

Abstract

This work investigated the decoration of the gold (Au) nanoparticles (NPs) on the TiO2 thin films for the applications in ethanol gas sensors. The Au-decorated TiO2 thin films (Au-TiO2) were prepared by the DC magnetron sputtering on the silicon (100) wafers and alumina substrates, interdigitated with Au electrodes. The distribution and size of Au nanoparticles were controlled by varying the sputtering time. Morphologies and element composition of the Au-TiO2 films were examined by field-emission scanning electron microscopy (FE-SEM) and energy-dispersive X-ray spectroscopy (EDX) respectively. The FE-SEM micrographs when the sputtering time was increased, the average size of the Au NPs was also increased. On the other hand, the distribution of the Au NPs was decreased. The change in size and distribution of the Au NPs consequently improved the response of ethanol gas sensors. The prepared Au-TiO2 was tested, in comparison with TiO2 reference films, as the ethanol sensors at 250-350oC in 50-1,000 ppm gas concentration. The results showed that the TiO2 thin film with Au-decorated at 6 sec sputtering time yielded the highest response of 514 at 350oC operating temperature and 1,000 ppm gas concentration.

Wearable, Flexible Ethanol Gas Sensor Based on TiO2 Nanoparticles-Grafted 2D-Titanium Carbide Nanosheets

“…Especially, ethanol gas detection has been widely recognized in various fields, such as industrial emission control, medical diagnosis, food processing, environmental pollution monitoring, etc. − Most commonly used ethanol gas sensing materials are wide band gap n-type semiconductors (e.g., TiO 2 , ZnO, etc. ), − which generally work at very high operating temperature (>150 °C). These semiconducting metal oxide gas sensing materials also exhibit high resistance and low reactive surfaces at room temperature which adversely affects their gas sensing performances resulting in poor sensitivity and long response and recovery times under atmospheric conditions. , Among various semiconducting metal oxide materials, nanostructured TiO 2 has been widely used for ethanol gas sensing application due to its low cost, less power consumption, wide band gap (3.1 eV), and high chemical and mechanical stability .…”

Nanoplasmonic response of porous Au-TiO2 thin films prepared by oblique angle deposition

“…The main advantage in the use of LSPR phenomenon for optical sensors is the fact that it is basically supported by nanoparticles that can be directly coupled to light, in contrast to Surface Plasmon Resonance (SPR) systems, which are dependent on prisms, optical fibres or gratings to be coupled with light [18][19][20]. Since the plasmon decay length in LSPR is much lower than in SPR [21], LSPR-based sensors have a much higher potential to be sensitive to subtle changes of the RI, as those induced by the adsorption of a few layers of analyte (bio)molecules [22][23][24] or even gas molecules [25][26][27][28]. Furthermore, in the particular case of gas sensing there are extremely low RI changes, which require the production of highly sensitive plasmonic thin films (i.e.…”

Enhancing the Sensitivity of Nanoplasmonic Thin Films for Ethanol Vapor Detection

“…A titanium dioxide (TiO 2 ) matrix and noble metal nanoparticles (Au or/and Ag) may be used independently in sensing applications [23][24][25][26][27][28][29][30], but it is known that their sensing capabilities are enhanced when they are combined [31]. Moreover, by using a mixture of these materials, the mechanical stability of TiO 2 is combined with the plasmonic sensing properties of Au.…”