Thermally stable mesoporous pH dyes encapsulated titania nanocomposites for opto-chemical sensing

Abstract For opto-chemical sensing, sol-gel-based phenol red encapsulated titania nanocomposite (PRTC) and creosol red encapsulated titania nanocomposite (CRTC) are synthesized and coated on optical fiber. Both nanocomposites revealed porous and crack-free structures, thermal stability, homogeneous distribution of nanocomposites elements, crystallinity, and chemical bonding between functional groups and Ti, validates PR and CR dye encapsulation in the titania matrix. The sensing mechanism relies on evanescent wave absorption and interpretation is to suppress the dye leaching at a dynamic pH range. The PRTC and CRTC matrix demonstrated sensitivity 1.66 counts/pH and 4.24 counts/pH at 453 nm, respectively, good linear response, reversibility, repeatability, and non-leaching behavior. The PRTC and CRTC sol exhibit pka values ∼ 8 and 7.5 at 570 nm and 577 nm, respectively. The CRTC sol revealed a time response around 0.28 s which is faster than PRTC ∼ 0.41 s. Experimental findings indicated that the prepared fiber sensors have practical function's ability.