Issue 3, 2023

Operando monitoring of a room temperature nanocomposite methanol sensor

Abstract

The sensing of volatile organic compounds by composites containing metal oxide semiconductors is typically explained via adsorption–desorption and surface electrochemical reactions changing the sensor's resistance. The analysis of molecular processes on chemiresistive gas sensors is often based on indirect evidence, whereas in situ or operando studies monitoring the gas/surface interactions enable a direct insight. Here we report a cross-disciplinary approach employing spectroscopy of working sensors to investigate room temperature methanol detection, contrasting well-characterized nanocomposite (TiO2@rGO-NC) and reduced-graphene oxide (rGO) sensors. Methanol interactions with the sensors were examined by (quasi) operando-DRIFTS and in situ-ATR-FTIR spectroscopy, the first paralleled by simultaneous measurements of resistance. The sensing mechanism was also studied by mass spectroscopy (MS), revealing the surface electrochemical reactions. The operando and in situ spectroscopy techniques demonstrated that the sensing mechanism on the nanocomposite relies on the combined effect of methanol reversible physisorption and irreversible chemisorption, sensor modification over time, and electron/O2 depletion–restoration due to a surface electrochemical reaction forming CO2 and H2O.

Graphical abstract: Operando monitoring of a room temperature nanocomposite methanol sensor

Supplementary files

Article information

Article type
Paper
Submitted
05 8 2022
Accepted
13 12 2022
First published
14 12 2022
This article is Open Access
Creative Commons BY license

Catal. Sci. Technol., 2023,13, 624-636

Operando monitoring of a room temperature nanocomposite methanol sensor

Q. Maqbool, N. Yigit, M. Stöger-Pollach, M. L. Ruello, F. Tittarelli and G. Rupprechter, Catal. Sci. Technol., 2023, 13, 624 DOI: 10.1039/D2CY01395A

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