Influence of bimetallic titanium and silver nanoparticles on physical and self-cleaning properties of zinc-silicate-tellurite glass

Abstract

In this study, the influence of two types of metallic (bimetallic) nanoparticles (NPs) including the pure silver (Ag) and titania (TiO2) on the feasibility of improving the self-cleaning properties of some silicate zinc tellurite glasses were determined. To achieve this goal, the best from 3 series of glasses with the composition of (79.93-z) TeO2 + 20ZnO + 0.06 SiO2 + 0.01TiO2 + z Ag, where (0.01 ≤ z ≤ 0.05 mol%) were prepared via the standard melt-quenching method. As-quenched samples were characterized using diverse analytical measurements. The role of the varying Ag NPs and TiO2 NPs (fixed content) on the hydrophobic and hydrophilic properties of the proposed glasses was evaluated. Highly transparent samples were obtained. The physical properties of the glasses such as the density, molar volume, theoretical crystalline volume, ionic and oxygen packing density of the best sample (S13) corresponded to 6.632 gcm-3, 21.716 cm3 mol-1, 12.729 cm3 mol-1, 0.586 and 82.946 molL-1, respectively. The surface plasmon resonance (SPR) absorption bands of these NPs were probed using the UV-Vis-NIR absorption spectroscopy. The X-ray diffraction (XRD) patterns verified the amorphous nature of the as-quenched samples. The energy dispersive X-ray (EDX) spectral analyses revealed the presence of the right elements in the composition. The scanning tunneling microscopy (STM) images and selected area electron diffraction (SAED) patterns confirmed the existence of the Ag and TiO2 NPs inside the glass matrix. The measured thermal parameters (the glass transition, crystallization, and melting temperatures) of the samples obtained using the differential thermal analyzer (DTA) exhibited their good thermal stability over a wide glass formation region. The recorded Fourier transform infrared (FTIR) spectra of the glasses were complemented via the Raman analysis. The mechanical properties of the studied glasses including the Vickers hardness, fracture toughness, and brittleness were calculated which showed optimum values of 3268.08 MPa, 4.794 MPa mm1/2, and 681.76 MPa mm1/2, respectively for the S13 sample. The surface structure, texture, and morphology of the samples were evaluated using the field-emission scanning electron microscopy (FESEM), atomic force microscopy (AFM) and water contact angle (WCA) measurements. The experimental results on the self-cleaning traits (WCA and surface tension) of the glasses were compared with the theoretical calculation using the Young, Young-Dupre, Wenzel and Cassie-Baxter models. The sample S3 disclosed hydrophobic nature (with Young WCA of 112.39°) and the sample S6 displayed hydrophilic nature (with Young WCA of 86.27°) when included with TiO2 NPs. It is affirmed that by manipulating the Ag NPs and TeO2 concentrations in the proposed glasses, an improved self–cleaning properties can be achieved. The S13 sample showed the optimum hydrophobic traits with normalized roughness of 0.733 Nm; WCA of Young 97.47°, Wenzel 95.47°, Cassie-Baxter 130.13°. The optimal surface tension for the Young, Wenzel and surface energy of Young-Dupre for the S13 sample corresponded to 0.1727 Nm-1, 0.1761 Nm-1, and 0.0626 Nm-1, respectively. The results were analyzed, interpreted, compared and discussed. The mechanism behind the nanoparticles inclusion in assisting the improvement of the self-cleaning characteristics was understood.