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. 2016 Dec 7;16(12):2079.
doi: 10.3390/s16122079.

Standardization, Calibration, and Evaluation of Tantalum-Nano rGO-SnO₂ Composite as a Possible Candidate Material in Humidity Sensors

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Free PMC article

Standardization, Calibration, and Evaluation of Tantalum-Nano rGO-SnO₂ Composite as a Possible Candidate Material in Humidity Sensors

Subbiah Karthick et al. Sensors (Basel). .
Free PMC article

Abstract

The present study focuses the development and the evaluation of humidity sensors based on reduced graphene oxide-tin oxide (rGO-SnO₂) nanocomposites, synthesized by a simple redox reaction between GO and SnCl₂. The physico-chemical characteristics of the nanocomposites were analyzed by XRD, TEM, FTIR, and Raman spectroscopy. The formation of SnO₂ crystal phase was observed through XRD. The SnO₂ crystal phase anchoring to the graphene sheet was confirmed through TEM images. For the preparation of the sensors, tantalum substrates were coated with the sensing material. The sensitivity of the fabricated sensor was studied by varying the relative humidity (RH) from 11% to 95% over a period of 30 days. The dependence of the impedance and of the capacitance with RH of the sensor was measured with varying frequency ranging from 1 kHz to 100 Hz. The long-term stability of the sensor was measured at 95% RH over a period of 30 days. The results proved that rGO-SnO₂ nanocomposites are an ideal conducting material for humidity sensors due to their high sensitivity, rapid response and recovery times, as well as their good long-term stability.

Keywords: nanocomposites; rGO-SnO2; relative humidity; sensor.

Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Schematic diagram of (a) the Humidity sensor; (b) the Measurement system.
Figure 2
Figure 2
FTIR spectra for (a) GO; (b) SnO2; (c) rGO-SnO2.
Figure 3
Figure 3
XRD pattern for (a) GO; (b) SnO2; (c) rGO-SnO2.
Figure 4
Figure 4
Raman spectra for (a) GO; (b) SnO2; (c) rGO-SnO2.
Figure 5
Figure 5
TEM image for (a) GO; (b) SnO2; (c) rGO-SnO2.
Figure 6
Figure 6
(a) The dependence of impedance on the RH for the rGO-SnO2 sensor measured at various frequencies; (b) The dependence of capacitance on the RH for the rGO-SnO2 sensor measured at various frequencies; (c) The sensitivity of the rGO-SnO2 sensor for different tested RH and frequencies.
Figure 7
Figure 7
Response and recovery curves of the rGO-SnO2 sensor.
Figure 8
Figure 8
The long-term stability of the rGO-SnO2 sensor after being exposed to 95% RH for 30 days.
Figure 9
Figure 9
The schematic of the proposed humidity sensing mechanism of the rGO-SnO2 nanocomposite.
Figure 10
Figure 10
SEM microstructure image for (a) SnO2; (b) rGO-SnO2.

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