Abstract:
NO2 gas is a harmful vapor that, when present in
large quantities, can impose severe threats on health and
environment. Gas sensors for NO2 have been in development
over the past few decades albeit selectivity towards the gas still
remains somewhat unperfected. A method was suggested to
improve selectivity towards NO2 by registering a unique and
recurring feature of the signal behavior as the selection criterion
i.e. gradient of sensor response. A parallel plate capacitive gas
sensor was fabricated taking graphene oxide as the dielectric
medium and was tested for NO2. Graphene oxide was
synthesized adhering to the Improved Hummer’s Method
(Tours Method) which produced sufficiently oxidized graphene
with a yield of 193% with respect to the starting material.
Synthesized graphene oxide was characterized by Fourier
Transform Infrared Spectroscopy (FTIR), Thermo Gravimetric
Analysis (TGA) and X-ray Diffractometry (XRD) techniques
ascertaining that the products were well oxidized with
acceptable d-spacing values. Sensor assembly was tested for
capacitance variation in the frequency domain, time domain and
under the influence of constant temperature ramp. The results
showed an average response time of about 1 minute to reach the
steady state signal and an equal time to go back to the initial
reference signal level once the target gas was evacuated.
Keywords— graphene oxide, capacitive sensor, selective
sensing, FTIR
