Optically active-thermally stable multi-dyes encapsulated mesoporous silica aerogel: A potential pH sensing nanomatrix

• Published in: Microporous and mesoporous materials Vol. 274; pp. 183 - 189
• Main Authors: Islam, Shumaila, Bakhtiar, Hazri, Shukri, W. Norsyuhada W., Aziz, Muhammad Safwan abd, Riaz, Saira, Naseem, Shahzad
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 15.01.2019
• Subjects: Indicator dyes; pH sensing; Silica matrix; Sol-gel method; Structural properties; Silica matrix; pH sensing; Indicator dyes; Sol-gel method; Structural properties
• ISSN: 1387-1811; 1873-3093
• DOI: 10.1016/j.micromeso.2018.07.049

Owing to the pH sensing applications, a mixture of four pH dyes (phenol red, bromophenol blue, creosol red, and phenolphthalein) is encapsulated in mesoporous silica aerogel by sol-gel method. FE-SEM analysis shows that dyes have great influence on the morphology of silica matrix. After encapsulation, silica aerogel matrix has low surface roughness ∼ 1.76 nm, ultra-thin layer 8.26 nm, high surface area of 433 m2/g, high optical transparency 77%, low refractive index ∼1.37 at 550 nm and thermally stable. The sensor response is optimized at pH 1–12 with the high value of pKa ∼8.35 at 565 nm without any leaching traces. The fast response time 0.71s in acidic medium (pH 1) and 0.36 s in basic medium (pH 12) is observed. From experimental findings, it can be concluded that fusion of sol-gel and nano-technologies can thus open a new way to synthesize thermally stable, high quality nano-porous optical material for sensing applications at dynamic pH range. [Display omitted] •Indicator dyes encapsulated mesoporous silica aerogel matrix is synthesized by sol-gel method for pH sensing.•Microscopic analysis shows that indicator dyes has great influence on the morphology of host silica matrix aerogel.•BET analysis confirmed that silica matrix has a high surface area of ∼433 m2/g after dyes encapsulation.•Thermally stable matrix has optical transparency 77 % and low refractive index ~ 1.37 at 550 nm after encapsulation.•The sensor response is optimized at pH 12 with pKa ~ 8.35 value at 565 nm. The fast response time 0.36 s is reported.