Abstract
Owing to the fast responsive fiber optic pH sensing, silica nanomatrix (SNM) and titania nanomatrix (TNM) are synthesized by the sol–gel method at low temperatures. Cresol red (CR) is immobilized within SNM and TNM for sensing evaluation. Crack-free, crystallinity and porous surfaces with an average particle size of CR-SNM ~45 ± 0.4 nm and CR-TNM ~24 ± 0.4 nm are observed through microscopic analysis. The is observed in CR immobilized matrices. The CR-SNM shows lower roughness ~7 nm, a large surface area ~380 m2/g, thermal stability at ≤400 °C, and a refractive index 1.47. Whereas, CR-TNM revealed high roughness 48 nm, surface area 211 m2/g, and refractive index 1.76. The sensitivity of the CR-SNM coated fiber is estimated at around 52.8 counts/pH which is greater than CR-TNM coated fiber sensitivity 14.53 counts/pH. Moreover, CR-SNM shows response time 0.17 s at pH 12 which is faster than CR-TNM time response 0.48 s.
Highlights
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Owing to fast responsive fiber optic pH sensing, silica nanomatrix (SNM) and titania nanomatrix (TNM) is synthesized by sol–gel method.
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CR immobilized SNM and TNM revealed crack-free and porous surfaces with average particle size 45 ± 0.4 nm and 24 ± 0.4 nm, respectively.
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CR-SNM shows lower roughness 7 nm, large surface area 380 m2/g, thermally stable at ≤400 °C, and refractive index 1.47.
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CR-TNM revealed high roughness 48 nm, surface area 211 m2/g, and refractive index 1.76 at 632 nm.
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The sensitivity of the CR-SNM and response time 0.17 s is observed higher than CR-TNM coated fiber 0.48 s at pH 12.
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This work is financially supported by a Fundamental Research Grant Scheme by Malaysia Ministry of Higher Education with a reference code of FRGS/1/2019/STG02/UTM/02/7 or a cost center number of R.J130000.7854.5F191.
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Islam, S., Aziz, M.S., Bakhtiar, H. et al. Thermally stable and fast responsive mesoporous cresol red functionalized silica and titania nanomatrices: fiber optic pH sensors. J Sol-Gel Sci Technol 99, 497–511 (2021). https://doi.org/10.1007/s10971-021-05604-z
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DOI: https://doi.org/10.1007/s10971-021-05604-z