Seed-Assisted Growth of TiO2 Nanowires by Thermal Oxidation for Chemical Gas Sensing

Abstract

Herein, we report the catalyst assisted growth of TiO2 one-dimensional (1D) nanowires (NWs) on alumina substrates by the thermal oxidation technique. RF magnetron sputtering was used to deposit a thin Ti metallic layer on the alumina substrate, followed by an Au catalytic layer on the Ti metallic one. Thermal oxidation was carried out in an oxygen deficient environment. The optimal thermal growth temperature was 700 °C, in a mixture environment composed by Ar and O2. As a comparison, Ti films were also oxidized without the presence of the Au catalyst. However, without the Au catalyst, no growth of nanowires was observed. Furthermore, the effect of the oxidation temperature and the film thickness were also investigated. SEM, TEM, and EDX studies demonstrated the presence of Au nanoparticles on top of the NWs, indicating that the Au catalyst drove the growth process. Raman spectroscopy revealed the Rutile crystalline phase of TiO2 NWs. Gas testing measurements were carried out in the presence of a relative humidity of 40%, showing a reversible response to ethanol and H2 at various concentrations. Thanks to the moderate temperature and the easiness of the process, the presented synthesis technique is suitable to grow TiO2 NWs for many different applications.

Recent Advancements in TiO2 Nanostructures: Sustainable Synthesis and Gas Sensing

“…These sensors have a wide range of potential applications, ranging from environmental monitoring to industrial process control and health and safety. This highlights the significance of 1D TiO 2 gas sensors as a promising technology for sensing various gases, including volatile organic compounds (VOCs), nitrogen oxides (NOx), and others [112][113][114][115][116].…”

Fabrication of ZnO and TiO2 Nanotubes via Flexible Electro-Spun Nanofibers for Photocatalytic Applications

“…They can be easily prepared in different morphologies (nanowires, nanofibers, nanoflowers, nanotubes, nanorods, etc.) by various facile and low-cost methods [ 8 , 10 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 ], making them adequate for a broad range of applications, such as photovoltaics [ 26 ], electronic devices [ 27 ], photocatalysis [ 28 ], water purification [ 29 ], dye-sensitized solar cells [ 30 ], sensors [ 31 ], and renewable energy [ 32 ].…”

Optimized Technologies for Cointegration of MOS Transistor and Glucose Oxidase Enzyme on a Si-Wafer

“…A technological solution to produce TiO 2 nanowires on a solid-state surface can be thermal oxidation for chemical gas sensing [ 18 ] or anodization for a glucose sensor [ 15 ]. By cointegration of the GOx enzyme with a flexible organic transistor, another glucose detector was produced [ 19 ]. A drain current increase was observed from 1 μA (in the absence of glucose) to 4 μA (in the presence of glucose) at V G = 3 V. However, the organic structure was a FET but not a MOS-FET.…”

“…By a separate experimental study, we investigated the nanostructured TiO 2 synthesis and the sensitive enzymatic membrane deposition on a Si-wafer. The following targets were exceeded versus the previous states [ 15 , 16 , 17 , 18 , 19 ]: (i) the fabrication steps of the ENFET include a channel conductivity correction, (ii) nanostructured Al 2 O 3 [ 20 ] or Si-porous [ 21 ] films are replaced by nanostructured TiO 2 films, (iii) nanostructured TiO 2 films and GOx membranes are characterized by SEM and FTIR, (iv) GOx membrane immobilization is optimized by alternative crosslink agents, and (v) a calibration curve is provided, and it is accompanied by an experimental model.…”