Conformal Titanyl Phosphate Surface Passivation for Enhancing Photocatalytic Activity

A conformal titanyl phosphate passivation with the thickness of ca. 5 nm on the surface of TiO2 nanoparticles for enhancing the photocatalytic degradation of organic pollutants and hydrogen production is described. The phosphate anion species bound to the surface of TiO2 promote the favorable kinetics of photocatalytic activity and influence the catalytic reaction pathway. By using a facile surfactant-assisted sol-gel process, the surface defects of TiO2 associated with deep traps was reduced and passivated by the phosphate anion species to form the titanyl phosphate. The strong bonds between the titanyl phosphate shell and TiO2 core provided a long-term photochemical stability in aqueous electrolytes with enhanced photocatalytic activities. The titanyl phosphate contributed to the production and stabilization of hydroxyl radicals on the surface of photocatalyst, which facilitated the efficient photooxidation of the organic pollutants. Further, enhancing the photocatalytic hydrogen production was achieved by the titanyl phosphate modified TiO2 (TP-TiO2). Consequently, the conformal titanyl phosphate passivation enhanced photocatalytic activity of TiO2. Comparing to the bare TiO2 nanoparticles, approximately two-fold higher photocatalytic H2 production rate was achieved by the TP-TiO2.