Novel thermally stable phosphorus-doped TiO2 photocatalyst synthesized by hydrolysis of TiCl4

A novel thermally stable phosphorous-doped TiO2 has been successfully synthesized by liquid hydrolysis of TiCl4 with ammonia, with hypophosphorous acid as the precursor of the dopant. The materials were characterized by X-ray diffraction, transmission electron microscopy, differential thermal analysis–thermogravimetry, N2 physical adsorption at 77 K, X-ray photoelectron spectroscopy and point of zero charge determination. It was found that increased calcination temperature gave an improvement of the anatase crystallinity and an enrichment of phosphorus species on the titania surface. The increased surface P content led to a linear enhancement of the specific adsorption capacity of methylene blue (MB) because of the Coulombic attractive force between the cationic dye and the negatively charged P-doped TiO2 surface. Importantly, the P-doped anatase TiO2 was stable even after calcination at 900 °C for 4 h, much more stable than the sample by the sol–gel method. This may be attributed to the partial transformation of amorphous titania to anatase during the hydrolysis of TiCl4. Photocatalytic tests showed that the P-doped TiO2 retained its high specific activity for the degradation of MB even after calcination at temperatures of 700–900 °C.

A simple, low-cost and reproducible method was developed for the synthesis of novel thermally stable P-doped TiO2 by liquid hydrolysis of TiCl4 and ammonia, with hypophosphorous acid as the precursor of the dopant. Photocatalytic tests showed that the P-doped TiO2 kept its superior specific activity at high calcination temperature (700–900 °C).Figure optionsDownload high-quality image (168 K)Download as PowerPoint slide