Thermally stable Au decorated silica-titania mesoporous nanocomposite for pH sensing evaluation

Abstract

Herein, doping/decoration of gold nanoparticles (AuNPs) within mesoporous silica-titania nanocomposite is achieved via a facile and co-assembly sol-gel method. Polyethylene glycol is used as a co-structure-directing-agent. For sensing analysis, a mixture of organic dyes i.e., bromophenol blue, phenol red, and cresol red is encapsulated in the AuST nanocomposite matrix. FESEM/EDX analysis shows a crack-free surface, porous network and uniform distribution of Au, Ti, Si, along with dye species. FTIR and XRD suggested the heterogeneous chemical bonding and crystallite size 24 nm after encapsulation. AuST nanocomposite shows thermally stable behavior after 450 °C even after co-dyes encapsulation. High surface area 322 ± 2.5 m2/g, pore diameter 30.2 Å, and pore volume 0.24 cm3/g, average surface roughness 10 nm, and refractive index 1.29 is advantageous for good sensing response at pH 1–12. The sensitivity is measured as 10 counts/pH at 441 nm. Moreover, good reversible response, fast response time 2.1 sec in acidic media, and 0.9 sec in basic media is observed.