Solution-Processed Functionalized Graphene Film Prepared by Vacuum Filtration for Flexible NO2 Sensors

Mbaye Dieng; Siva Sankar; Pingping Ni; Ileana Florea; Pedro Alpuim; Andrea Capasso; Abderrahim Yassar; Fatima Zahra Bouanis

doi:10.3390/s23041831

Solution-Processed Functionalized Graphene Film Prepared by Vacuum Filtration for Flexible NO₂ Sensors

Sensors (Basel). 2023 Feb 7;23(4):1831. doi: 10.3390/s23041831.

Authors

Mbaye Dieng^{1

2}, Siva Sankar³, Pingping Ni^{1

2}, Ileana Florea², Pedro Alpuim^{3

4}, Andrea Capasso³, Abderrahim Yassar², Fatima Zahra Bouanis^{1

2}

Affiliations

¹ COSYS-IMSE, Univ. Gustave Eiffel, 77454 Marne-la-Vallée, France.
² Laboratory of Physics of Interfaces and Thin Films, UMR 7647 CNRS/Ecole Polytechnique, IP Paris, 91128 Palaiseau, France.
³ International Iberian Nanotechnology Laboratory, 4715-330 Braga, Portugal.
⁴ Center of Physics, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal.

Abstract

Large-scale production of graphene nanosheets (GNSs) has led to the availability of solution-processable GNSs on the commercial scale. The controlled vacuum filtration method is a scalable process for the preparation of wafer-scale films of GNSs, which can be used for gas sensing applications. Here, we demonstrate the use of this deposition method to produce functional gas sensors, using a chemiresistor structure from GNS solution-based techniques. The GNS suspension was prepared by liquid-phase exfoliation (LPE) and transferred to a polyvinylidene fluoride (PVDF) membrane. The effect of non-covalent functionalization with Co-porphyrin and Fe-phthalocyanines on the sensor properties was studied. The pristine and functionalized GNS films were characterized using different techniques such as Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), X-ray diffraction (XRD), and electrical characterizations. The morphological and spectroscopic analyses both confirm that the molecules (Co-porphyrin and Fe-phthalocyanine) were successfully adsorbed onto the GNSs surface through π-π interactions. The chemiresistive sensor response of functionalized GNSs toward the low concentrations of nitrogen dioxide (NO₂) (0.5-2 ppm) was studied and compared with those of the film of pristine GNSs. The tests on the sensing performance clearly showed sensitivity to a low concentration of NO₂ (5 ppm). Furthermore, the chemical modification of GNSs significantly improves NO₂ sensing performance compared to the pristine GNSs. The sensor response can be modulated by the type of adsorbed molecules. Indeed, Co-Por exhibited negative responsiveness (the response of Co-Por-GNS sensors and pristine GNS devices was 13.1% and 15.6%, respectively, after exposure to 0.5 ppm of NO₂). Meanwhile, Fe-Phc-GNSs induced the opposite behavior resulting in an increase in the sensor response (the sensitivity was 8.3% and 7.8% of Fe-Phc-GNSs and pristine GNSs, respectively, at 0.5 ppm NO₂ gas).

Keywords: Co-porphyrin; Fe-Phthalocyanine; functionalization; gas sensor; graphene nanosheets; liquid-phase exfoliation; nitrogen dioxide.

Grants and funding

This research was partially funded by COMPETE 2020—Operational Programme for Competitiveness and Internationalization and FCT—Science and Technology Foundation under the Portugal 2020 Partnership Agreement through the European Regional Development Fund, within the project “GEMIS-Graphene-enhanced Electro Magnetic Interference Shielding” with grant number POCI-01-0247-FEDER-045939. FCT also supported this research in the framework of the Strategic Funding UIDB/04650/2020. The authors acknowledge financial support from the French state managed by the National Research Agency under the Investments for the Future program under the references ANR-10-EQPX-50, pole NanoMAX, and pole NanoTEM. Part of the TEM analysis was carried out at Centre Interdisciplinaire de Microscopie électronique de l’X (CIMEX), gratefully acknowledged. This work has benefited from a French government grant by ANR within the frame of the national program Investments for the Future ANR-11-LABX022-01 (LabEx MMCD project).