Titania-lanthanum phosphate photoactive and hydrophobic new generation catalyst

Abstract

Titania-lanthanum phosphate nanocomposites with multifunctional properties have been synthesized by aqueous sol-gel method. The precursor sols with varying TiO(2):LaPO(4) ratios were applied as thin coating on glass substrates in order to be transparent, hydrophobic, photocatalytically active coatings. The phase compositions of the composite powders were identified by powder X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HR-TEM). The anatase phase of TiO(2) in TiO(2):LaPO(4) composite precursors was found to be stable even on annealing at 800 degrees C. The glass substrates, coated with TL1 (TiO(2):LaPO(4) composition with 1 mol% LaPO(4)) and TL50 (composite precursor containing TiO(2) and LaPO(4) with molar ratio 1:1) sols and annealed at 400 degrees C, produced contact angles of 74 degrees and 92 degrees, respectively, though it is only 62 degrees for pure TiO(2) coating. The glass substrates, coated with TL50 sol, produced surfaces with relatively high roughness and uneven morphology. The TL1 material, annealed at 800 degrees C, has shown the highest UV photoactivity with an apparent rate constant, k(app)=24 x 10(-3) min(-1), which is over five times higher than that observed with standard Hombikat UV 100 (k(app)=4 x 10(-3) min(-1)). The photoactivity combined with a moderate contact angle (85.3 degrees) shows that this material has a promise as an efficient self-cleaning precursor.