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Cover page for Operando Studies of a Nanocomposite Methanol Sensor

Collaborative research from Professor Gϋnther Rupprechter’s group and the laboratory of Professor Francesca Tittarelli, Department of Materials, Environmental Sciences and Urban Planning, Università Politecnica delle Marche, Ancona, Italy was recently highlighted on the front cover of the journal Catalysis Science & Technology. The first author Qaisar Maqbool spent 6 months at IMC from June 2021 to December 2021. The short term scientific mission (STSM) aimed at realtime time (operando) monitoring of working nanocomposite (TiO2@rGO-NC) and reduced-graphene oxide (rGO) methanol sensors. A dedicated operando-experimental design was realized for the first time by combining a customized chemiresistive gas sensor chamber with DRIFTS and MS.

Cover CST

In a themed issue on “In situ and operando spectroscopy in catalysis”, Q. Maqbool et al. report operando vibrational spectroscopy of working nanocomposite methanol sensors at room temperature. The analysis of molecular processes on chemiresistive gas sensors is typically based on indirect evidence, whereas in situ or operando studies monitoring the gas/surface interactions would enable a direct insight. The described cross-disciplinary approach thus applied 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 electrical resistance. The sensing mechanism was further studied by mass spectroscopy (MS), revealing the surface electrochemical reactions. The operando and in situ spectroscopies demonstrated that the sensing mechanism on the nanocomposite relies on the combined effect of methanol reversible physisorption and irreversible chemisorption, formation of a conduction layer, sensor modification over time, and electron/O2 depletion-restoration due to a surface electrochemical reaction forming CO2 and H2O.

Methanol interactions

Methanol interactions with the sensors at room temperature were examined by (quasi) operando-DRIFTS and Operando MS.

Original publication

Qaisar Maqbool, Nevzat Yigit, Michael Stöger-Pollach, Maria Letizia Ruello, Francesca Tittarelli, and Günther Rupprechter, Catal. Sci. Technol., 2023, 13, 624-636, opens an external URL in a new window

link to cover page:, opens an external URL in a new window

Research partially supported by COST ACTION CA19118 “High-performance Carbon-based composites with Smart properties for Advanced Sensing Applications (EsSENce)”, funded by COST (European Cooperation in Science and Technology;  Instrumental access was in part supported by the Austrian Science Fund (FWF) (SFB TACO F81-P08).