Enhanced Gd Doped TiO2 NPs-PDMS Nanocomposites as Protective Coatings for Bio-Calcarenite Stone: Preliminarily Analysis

Abstract

The main objectives of this research are the development and characterization of pure and Gd-doped TiO2 nanoparticles (NPs) with low doping amounts (doping ions/Ti ratio varies between 0.1 and 3 mol%) and self-cleaning activity to be used when mixed with binder as protective coatings on monument surfaces. The prime objectives of this study are to synthesize nanopowders with controllable nanosize particles, spherical shape, anatase phase, and enhanced photo-response activity. Different coatings composed of as-synthesized nanoparticles and binder were applied to stone samples (Lecce stone). The developed coatings are intended to induce negligible colourimetric variation on the treated surface, have a good water repellence feature, and have a good distribution on the studied stone. XRD, DLS, SEM, and UV-Vis analyses were performed to analyze TiO2 NPs. The efficiency of the as-prepared NPs was estimated by testing their photocatalytic activity under UV and visible light. Chromatic measurements, static contact angle measurements, optical microscope observations, and SEM-EDS analysis were performed to analyze thin films applied to Lecce stone. The results showed that samples doped with low concentrations (≤1 mol%) of gadolinium in conjunction with PDMS can be considered as good candidates for protecting monument surfaces for this type of stone.