Organic dyes influence on structural, optical, and pH sensing characteristics of gold-supported titania nanoparticles at low temperature

In arrears to pH sensing functions, gold-supported titania nanoparticles (AuTNPs) are synthesized at a low temperature 90 degrees C by the sol-gel technique. Two different dyes phenol red and creosol red dye are encapsulated in AuTNPs nanocomposite. Void-free AuTNPs exhibited the particle size 45 nm which is reduced to 28 nm and 29 nm after PR and CR encapsulation. Heterogeneous bonding confirms the good interaction of PR and CR dye within AuTNPs. The transmittance decreased from 80% to 71% and 65% because of pores presence after dye encapsulation, while the refractive index increased from 1.06 to 1.07 and 1.09 at 633 nm, and bandgap energy varied from 3.17 eV to 3.1 eV and 3.42 eV of AuTNPs, PR-AuTNPs, and CR-AuTNPs, respectively. The CR-AuTNPs exhibited a color time response 0.2 s at pH 12 and a high pKa 9.9 which is greater than PR-AuTNPs' pka similar to 8 and a time response of 0.4 s. Experimental findings suggested that CR-AuTNPs possessed fast responses as pH sensors. [GRAPHICS] .