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

摘要

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 similar to 1.76 nm, ultra-thin layer 8.26 nm, high surface area of 433 m(2)/g, high optical transparency 77%, low refractive index similar to 1.37 at 550 nm and thermally stable. The sensor response is optimized at pH 1-12 with the high value of pKa similar to 8.35 at 565 nm without any leaching traces. The fast response time 0.71s in acidic medium (pH 1) and 0.36 sin 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.