Nanocomposite of hematite-doped titanium dioxide on carbon for use in cold pigments paints

[Display omitted] •Nanocomposites of hematite doped TiO2 on carbon were successfully synthesized by the Pechini method.•The pH during synthesis could effectively improve the dispersion of Fe2O3-TiO2 nanoparticles in the carbon matrix.•The nanocomposites exhibited improved optical properties, with higher absorption coefficient and broader absorption band.•The Fe2O3-TiO2@carbon nanocomposites could be a suitable pigment for low temperature applications. The use of cold pigments is an effective strategy for minimizing energy consumption in buildings. This study describes the synthesis of a hematite-doped titanium dioxide (Fe2O3-TiO2@carbon) nanocomposite (NC) using the Pechini method. Glycerol and citric acid were utilized in the synthesis of the initial polymeric matrix of this NC. The weight ratio of iron (0, 0.6, 0.8, and 1 %) was varied in the synthesis of the nanoparticles (NPs) of TiO2. Thermal treatments at 700 °C and 800 °C were used to eliminate the polymeric templates. X-ray diffraction, scanning electron microscopy, near infrared Fourier transform spectroscopy, and UV–Vis spectroscopy techniques were utilized to analyze the optical and morphological properties of the samples. The NC obtained at pH 0.5 comprised a mix of rutile and pseudobrookite phases of TiO2, while those grown at pH 5 consisted of rutile and anatase phases. In both situations, the average size of the TiO2-NPs was within the range of 18–45 nm. Samples grown at pH 5 with 0.6 % iron addition exhibited the highest NIR reflectance. These findings suggest that the NC of Fe2O3-TiO2@carbon could be a suitable pigment for low-temperature applications.