Environmentally friendly YIn0.9Fe0.1O3-ZnO yellow pigment displaying near infra red (NIR) reflectance and photocatalytic activity

In this research, we produced ochre/yellow pigments of YIn0.9Fe0.1O3, combined with ZnO pigments, through a citrate-assisted sol-gel approach. We investigated the impact of varying ZnO addition methods (incorporated into the sol-gel bath and physically mixed with YIn0.9Fe0.1O3 pigments) on their color properties, near-infrared (NIR) reflectance and photocatalytic activity. The effect of the different ZnO addition methods was investigated on pprecursors and final calcined pigments through X-ray diffraction (XRD), Vis-NIR reflectance, Fourier transform infrared spectroscopy (FT-IR) Scanning Electron Microscope (SEM) and thermal analyses such as thermogravimetry (TGA), and differential scanning calorimetry (DSC). The synthesized nanocomposites were evaluated for their photocatalytic characteristics by examining the degradation of 4-Nitrophenol (4-NP) when exposed to UV radiation. The potential environmental applications of the pigments were investigated not only for direct pollutant degradation but also in terms of energetic sustainability. In fact, the developed pigments can be employed as passive cooling materials to mitigate the temperature of buildings, thus dramatically reducing energy consumption. For this reason, the pigments were embedded into a polymeric binder and coated onto roofing aluminum sheets. The obtained coatings were investigated in terms of NIR reflectance and heat adsorption. The photocatalytic ability of the coatings was assessed by the degradation of 4-NP and methylene blue (MB) under xenon arc lamp. The results obtained indicate the feasibility of producing a pale yellow pigment with both NIR reflectance and photocatalytic capabilities.