Mesoporous and thermally stable phenol red encapsulated Ag-SiO2 and zincite decorated Ag-SiO2 opto-chemical Sensor

Abstract

Sol-gel-based silver-doped silicon dioxide (Ag-SiO2) and zincite-decorated silver-doped silicon dioxide (Z-Ag-SiO2) are synthesized at low temperatures (80 °C). The pH indicator dye phenol red (PR) is encapsulated in Ag-SiO2 (AS) and Z-Ag-SiO2 (ZAS) for pH assessment at dynamic pH 12. Thermally stable PR encapsulated AS nanocomposite and PR encapsulated ZAS nanocomposite revealed porous nanostructure with a crystallite size of approximately 0.85 nm and 1.21 nm. The PR/AS and PR/ZAS nanocomposites also feature a surface area of about 438 m2g−1 and 370 m2g−1, respectively. The PR/AS and PR/ZAS demonstrate a pKa of 10.9 and 10.2 at 560 nm, and a rapid color response of approximately 0.46 s and 0.25 s at pH 12.