Ternary Nanocomposites Based on Oxidized Carbon Nanohorns as Sensing Layers for Room Temperature Resistive Humidity Sensing

Bogdan-Catalin Serban; Cornel Cobianu; Octavian Buiu; Marius Bumbac; Niculae Dumbravescu; Viorel Avramescu; Cristina Mihaela Nicolescu; Mihai Brezeanu; Cristina Pachiu; Gabriel Craciun; Cristiana Radulescu

doi:10.3390/ma14112705

Ternary Nanocomposites Based on Oxidized Carbon Nanohorns as Sensing Layers for Room Temperature Resistive Humidity Sensing

Materials (Basel). 2021 May 21;14(11):2705. doi: 10.3390/ma14112705.

Authors

Bogdan-Catalin Serban^{1

2}, Cornel Cobianu^{1

2

3}, Octavian Buiu^{1

2}, Marius Bumbac^{4

5}, Niculae Dumbravescu^{1

2}, Viorel Avramescu¹, Cristina Mihaela Nicolescu⁵, Mihai Brezeanu⁶, Cristina Pachiu¹, Gabriel Craciun¹, Cristiana Radulescu^{4

5}

Affiliations

¹ National Institute for Research and Development in Microtechnologies-IMT Bucharest, 126 A Erou Iancu Str., 077190 Voluntari, Romania.
² Research Center for Integrated Systems, Nanotechnologies, and Carbon-Based Nanomaterials (CENASIC)-IMT, Str. Erou Iancu Nicolae 126A, 077190 Voluntari, Romania.
³ Academy of Romanian Scientists, Science, and Technology of Information Section, Ilfov Str., nr. 3, Sector 5, 050044 Bucharest, Romania.
⁴ Sciences and Advanced Technologies Department, Faculty of Sciences and Arts, Valahia University of Targoviste, 13 Sinaia Alley, 130004 Targoviste, Romania.
⁵ Institute of Multidisciplinary Research for Science Technology, Valahia University of Targoviste, 13 Sinaia Alley, 130004 Targoviste, Romania.
⁶ Faculty of Electronics, Telecommunications, and I.T., University Politehnica of Bucharest, Romania, 1-3 Iuliu Maniu Blvd., 6th district, 061071 Bucharest, Romania.

Abstract

This paper presents the relative humidity (RH) sensing response of a resistive sensor employing sensing layers based on a ternary nanocomposite comprising graphene oxide-oxidized carbon nanohorns-polyvinylpyrrolidone (GO-CNHox-PVP), at 1/1/1, 1/2/1, and 1/3/1 w/w/w mass ratios. The sensing structure is composed of a silicon substrate, a SiO₂ layer, and interdigitated transducers (IDT) electrodes, on which the sensing layer is deposited via the drop-casting method. The morphology and the composition of the sensing layers are investigated through scanning electron microscopy (SEM) and RAMAN spectroscopy. The RH sensing capability of each carbonaceous nanocomposite-based thin film was analyzed by applying a current between the two electrodes and by measuring the voltage difference when varying the RH from 0% to 100% in humid nitrogen. The sensors have a room temperature response comparable to that of a commercial humidity sensor and are characterized by a rapid response, excellent linearity, good sensitivity, and recovery time. The manufactured sensing devices' transfer functions were established, and we extracted the response and recovery times. While the structures with GO/CNHox/PVP at 1/1/1 ratio (w/w/w) had the best performance in terms of relative sensibility, response time, and recovery time, the sensors employing the GO/CNHox/PVP nanocomposite at the 1/2/1 ratio (w/w/w) had the best linearity. Moreover, the ternary mixture proved to have much better sensing properties compared to CNHox and CNHox-PVP-based sensing layers in terms of sensitivity and linearity. Each component of the ternary nanocomposites' functional role is explained based on their physical and chemical properties. We analyzed the potential mechanism associated with the sensors' response; among these, the effect of the p-type semiconductor behavior of CNHox and GO, correlated with swelling of the PVP, was dominant and led to increased resistance of the sensing layer.

Keywords: graphene oxide (GO); oxidized carbon nanohorns (CNHox); p-type semiconductor; polyvinylpyrrolidone (PVP); resistive humidity sensor; swelling.

Abstract

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