The role of surface stoichiometry in NO2 gas sensing using single and multiple nanobelts of tin oxide

Author(s)

Masteghin, Mateus G. ; Silva, Ranilson A. ; Cox, David C. ; Godoi, Denis R. M. ; Silva, S. Ravi P. ; Orlandi, Marcelo O.

• Document type: Journal article
• Source: Physical Chemistry Chemical Physics; v. 23, n. 16, p. 10-pg., 2021-04-19.

Abstract

Typically used semiconducting metal oxides (SMOs) consist of several varying factors that affect gas sensor response, including film thickness, grain size, and notably the grain-grain junctions within the active device volume, which complicates the analysis and optimisation of sensor response. In comparison, devices containing a single nanostructured element do not present grain-grain junctions, and therefore present an excellent platform to comprehend the correlation between nanostructure surface stoichiometry and sensor response to the depletion layer (Debye length, L-D) variation after the analyte gas adsorption/chemisorption. In this work, nanofabricated devices containing SnO2 and Sn3O4 individual nanobelts of different thicknesses were used to estimate their L-D after NO2 exposure. In the presence of 40 ppm of NO2 at 150 degrees C, L-D of 12 nm and 8 nm were obtained for SnO2 and Sn3O4, respectively. These values were associated to the sensor signals measured using multiple nanobelts onto interdigitated electrodes, outlining that the higher sensor signal of the Sn4+ surface (up to 708 for 100 ppm NO2 at 150 degrees) in comparison with the Sn2+ (up to 185) can be explained based on a less depleted initial state and a lower surface electron affinity caused by the Lewis acid/base interactions with oxygen species from the baseline gas. To support the proposed mechanisms, we investigated the gas sensor response of SnO2 nanobelts with a higher quantity of oxygen vacancies and correlated the results to the SnO system. (AU)

• FAPESP's process: 17/26219-0 - Study of Single Element Chemical Sensor Devices based on Semiconducting Metal Oxide Materials
• Grantee: Marcelo Ornaghi Orlandi
• Support Opportunities: Regular Research Grants
• FAPESP's process: 13/07296-2 - CDMF - Center for the Development of Functional Materials
• Grantee: Elson Longo da Silva
• Support Opportunities: Research Grants - Research, Innovation and Dissemination Centers - RIDC
• FAPESP's process: 17/12870-0 - Gas sensor response of devices made up by multiples and single tin dioxide-based nanobelts
• Grantee: Mateus Gallucci Masteghin
• Support Opportunities: Scholarships abroad - Research Internship - Master's degree
• FAPESP's process: 15/21033-0 - Comparison of the gas sensor response of devices with single and multiple tin oxide nanobelts
• Grantee: Mateus Gallucci Masteghin
• Support Opportunities: Scholarships in Brazil - Master