Abstract
Natural carbon powder has been used as a precursor to prepare two main types of sensitising agents of nitrogen-doped carbon nanoparticles (N-CNPs) and nitrogen-doped graphene quantum dots coupled to nanosheets (N-GQDs-NSs) by using simple treatments of chemical oxidation and centrifugation separation. Characterization based on FTIR, XPS, XRD, Raman spectroscopy, FE-SEM, HR-TEM, AFM, UV-Vis and FL, revealed successful doping carbon nanoparticle with nitrogen with an average plane dimension of 50 nm and relatively smooth surface. The versatility of the prepared samples as sensitising agents was developed and established by exploiting its ability for detection of volatile organic compounds via simple optical fibre based sensing configuration. The comparative experimental studies on the proposed sensor performance indicate fast response achieved at a few tens of seconds and excellent repeatability in exposure to the methanol vapour. The low limit of detection of 4.3, 4.9 and 10.5 ppm was obtained in exposure to the methanol, ethanol and propanol vapours, respectively, in the atmosphere condition. This study gives insights into the chemical/physical mechanism of an enhanced economic optical fibre based gas sensor and illustrates it for diverse sensing applications, especially for chemical vapour remote detection and future air quality monitoring.
Highlights
Specific advantages such as electromagnetic immunity, multiplexation capacity, online monitoring and remote introduce optical fibre sensors as a real alternative in recent years[16,17,18]
The obvious broad peak extended from 1000 cm−1 to 1400 cm−1 for natural carbon which is converted to the peaks centered at 1390 cm−1, 1244 cm−1 and a notable peak of 1050 cm−1 for nitrogen-doped carbon nanoparticles (N-CNPs) implying the presence of C-N, C-O-C and C-O groups, respectively
They were disappeared in N-GQDs-NSs structure in consistence with the X-ray photoelectron spectroscopy (XPS) results displaying less oxo-and nitro-groups
Summary
Specific advantages such as electromagnetic immunity, multiplexation capacity, online monitoring and remote introduce optical fibre sensors as a real alternative in recent years[16,17,18]. G. evanescent field-based optical fibre sensors, can significantly modify the interaction between the device and the surrounding environment and supply an attractive opportunity for sensing application In other words, this sensor takes advantage of the synergy between both the properties of nanostructure active layers as well as the ones that www.nature.com/scientificreports/. The evanescent field optical fibre sensor often suffers from lower sensitivity caused by both the inherent limitation of the employed nanostructures coated on the optical fibre and the optical sensing setup that does not satisfy the rigorous detection demands of a specific analyte with fractional contents In this regard, two main lines have to be traced in the optical fibre-based sensors roadmap: (a) providing a suitable optical fibre sensor configuration to make an efficient transducer; (b) maximizing the analyte interaction with the sensing surface by choosing a proper nanostructure for its efficient deposition on the optical fibre in accordance with the analyte. Combination of such reactive centres in cooperation with hydrogen bonding and van der Waals forces control the selecting pattern and sensing performance
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