Preparation of porous titanium phosphate glass-ceramics for NH3 gas adsorption with self-cleaning ability

Porous glass-ceramics with a skeleton of γ-Ti(HPO4)2·2H2O crystals are derived from glasses in the Li2O–CaO–TiO2–P2O5 system by utilizing spinodal-type phase separation, crystallization and subsequent acid treatment of the resulting glass-ceramics. The glass-ceramics have both micro-sized (1–2 μm) and nano-sized pores (5–30 nm), and they adsorb polar molecules. In the present work, porous TiO2 layers of 200–500 nm thickness were successfully deposited on the surfaces of the glass-ceramics by an infiltration of Ti(OCH(CH3)2)4 and water vapor treatment at 100 °C under 100% relative humidity. X-ray diffractometry and laser Raman spectroscopy revealed the formation of anatase crystals. The resulting anatase-modified porous glass-ceramics show high activities for NH3 adsorption as well as for photodecomposition of the adsorbed NH3 molecules.