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

Hashitha M M Munasinghe Arachchige,Nanda Gunawardhana,Dario Zappa,Nuwan H Attanayake,Nicola Poli,Elisabetta Comini

doi:10.3390/nano10050935

Hashitha M M Munasinghe Arachchige, Nanda Gunawardhana + Show 4 more

Open Access

https://doi.org/10.3390/nano10050935

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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.

Highlights

The field of one-dimensional (1D) nanomaterial research has witnessed a remarkable growth in its attempt to drive new technologies and improve existing ones
We report for the first time the seed-assisted synthesis of TiO2 NWs directly on the alumina substrate by thermal oxidation, starting from a thin Ti layer deposited on the substrate and using only small amounts of oxygen as oxidizing gas
Morphological and Structural Characterization As pointed out in the previous section, TiO2 NWs were grown on the alumina substrate by thermAasl opxoiidnatteidonoiuntainn othxyegpernevdieofuicsiesnetcetinovni,roTniOm2enNt.WFsigwureere2 igllruoswtrnatoens tthheeSaElMumainnda TsuEbMstirmataegbesy othf eTrim(2a0l0oxnimdatthioicnkinneassn) osaxmygpelnesd, egfircoiwennt aetn7v0ir0o°nCmwenitth

Summary

Introduction

The field of one-dimensional (1D) nanomaterial research has witnessed a remarkable growth in its attempt to drive new technologies and improve existing ones. There has been a significant interest over the past decade in 1D nanomaterials owing to their unique physical and chemical properties These unique properties are impelled by an enhanced surface area and surface electronic properties that can vary enormously from those of their bulk counterparts [1,2]. Among these materials, TiO2 1D nanostructures received enormous attraction in the fields of photo electrochemical water spitting [3], solar cells [4], and optical devices [5] due to their compatible band-edge positions, high resistance to photo corrosion, high photocatalytic activity, lack of toxicity, and low cost [6]. TiO2 exhibits a great potential for the fabrication of gas sensors due to its high stability at a high working temperature and low cost [10,11,12]

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