Sol-gel based thermally stable mesoporous TiO2 nanomatrix for fiber optic pH sensing

Abstract

Thermally stable acid catalyzed mesoporous titania (TiO2) nanomatrices are obtained by sol–gel method for fiber optic pH sensing. These synthesized nanoparticles are annealed at 300 °C, at two time intervals i.e., 1 h and 2 h, characterized with several analytical techniques such as FE-SEM/EDS, AFM, XRD, FTIR, TGA, and Brunauer–Emmett–Teller (BET) analysis. Microscopic analysis shows that synthesized nanoparticles have crack-free, dense and homogeneous surface with low surface roughness (4.4–5.9 nm). EDS mapping confirms the uniform distribution of Ti in all samples. XRD findings revealed the TiO2 anatase phase. BET analysis shows that the mesoporous synthesized TiO2 nanoparticles have surface areas 169 m2/g and average pore diameter 39.2 Å. However, surface area is decreased to 113 and 102 m2/g and average pore diameter increased up to 62.36 and 68.18 Å after 1 h and 2 h heat treatment, respectively. Furthermore, the sensing activity of phenolphthalein (phph) doped mesoporous TiO2 nanoparticles/matrix is found to be high at pH 12 without any leaching/cracking.