Amorphous and Crystalline Titanium-Ammonium Phosphates: Synthesis, Photocatalytic and Photoprotective Properties

Amorphous and crystalline titanium-ammonium phosphates TiOH(PO)[(NH)PO] were synthesized by the hydrothermal method. It is shown that the minimum temperature and processing time for the crystallization of the TiOH(PO)[(NH)PO] phase are 160°C and 12 hours, respectively. At the same time, NH and PO ions are present in X-ray amorphous samples, similar to the crystalline compound, and during crystallization, a decrease in the content of water or hydroxyl groups and an increase in molar ratio of P : Ti are observed. X-ray amorphous samples consist of isotropic particles 10–15 nm in size, while crystalline samples contain rhombus-shaped plates with smaller primary particles in their structure. X-ray amorphous and crystalline titanium-ammonium phosphates have low photocatalytic activity. The sun protection factor of X-ray amorphous samples, determined according to the international standard ISO 24443, is comparable to the sun protection factor of commercially available titanium dioxide.