Issue 46, 2009
From the journal:

Physical Chemistry Chemical Physics

A model for the response towards oxidizing gases of photoactivated sensors based on individual SnO2nanowires

Joan Daniel Prades,†*a   Roman Jimenez-Diaz,a   Marta Manzanares,a   Francisco Hernandez-Ramirez,†b   Albert Cirera,a   Albert Romano-Rodriguez,a   Sanjay Mathurcd  and  Joan Ramon Moranteae  

* Corresponding authors

a EME/XaRMAE/IN2UB, Departament d’Electrònica, Universitat de Barcelona, C/ Martí i Franquès 1, Planta 2, E-08028 Barcelona, Spain
E-mail: dprades@el.ub.es

b Electronic Nanosystems S. L., Barcelona, Spain
E-mail: fhernandezra@e-nanos.com

c Department of Inorganic Chemistry, University of Cologne, D-50939 Cologne, Germany

d Nanocrystalline Materials and Thin Film Systems, Leibniz-Institute of New Materials, D-66123 Saarbruecken, Germany

e Institut de Recerca en Energia de Catalunya (IREC), C/ Josep Pla 2, B2, Ground Floor, E-08019 Barcelona, Spain
E-mail: jrmorante@irec.cat

Abstract

The paper presents a quantitative model to elucidate the role of impinging photons on the final response towards oxidizing gases of light-activated metal oxide gas sensors. The model is based on the competition between oxygen molecules in air and oxidizing target gases (such as NO2) for the same adsorption sites: the surface oxygen vacancies (OV). The model fairly reproduces the experimental measurements of both the steady-state and the dynamic response of individual SnO2nanowires towards oxidizing gases. Quantitative results indicate that: (1) at room temperature NO2 adsorbs onto OV more avidly than oxygen; (2) the flux of photons and the NO2 concentration determine the partition of the two gas populations at the surface; and (3) the band-to-band generation of electron-hole pairs plays a significant role in the photodesorption process of gas molecules. The model also offers a methodology to estimate some fundamental parameters, such as the adsorption rates and the photodesorption cross sections of oxidizing molecules interacting with the nanowires’ surface. All these results, enabled by the use of individual nanowires, provide deep insight about how to control the response of metal oxide nanowires towards oxidizing gases, paving the way to the development and consolidation of this family of low consumption conductometric sensors operable at room temperature.

Graphical abstract: A model for the response towards oxidizing gases of photoactivated sensors based on individual SnO2nanowires

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Article information

DOI
https://doi.org/10.1039/B915646A
Article type
Paper
Submitted
30 Jul 2009
Accepted
16 Sep 2009
First published
14 Oct 2009

Phys. Chem. Chem. Phys., 2009,11, 10881-10889

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A model for the response towards oxidizing gases of photoactivated sensors based on individual SnO2nanowires

J. D. Prades, R. Jimenez-Diaz, M. Manzanares, F. Hernandez-Ramirez, A. Cirera, A. Romano-Rodriguez, S. Mathur and J. R. Morante, Phys. Chem. Chem. Phys., 2009, 11, 10881 DOI: 10.1039/B915646A

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