Direct formation of new, phase-stable, and photoactive anatase-type Ti_(1-2X)Nb_XSc_XO_2 solid solution nanoparticles by hydrothermal method

摘要

A new anatase phase of photoactive Ti_(1-2X)Nb_XSc_XO_2 (X = 0-0.2) solid solutions was directly formed as nanoparticles from precursor solutions of TiOSO_4, NbCl_5, and Sc(NO_3)_3 under mild hydrothermal conditions at 180 ℃ for 5 h using the hydrolysis of urea. With the increase of the content of niobium and scandium from X = 0 to 0.2, the lattice parameters a_0 and c_0, the crystallite size, and the optical band gap of anatase gradually increased. Their photocatalytic activity and adsorptivity were evaluated separately by the measurement of the concentration of methylene blue (MB) remained in the solution in the dark or under UV-light irradiation. The anatase-type Ti_(1-2X)Nb_XSc_XO_2 (X = 0.05) showed approximately two times and three times as high photocatalytic activity as those of the hydrothermal anatase-type pure TiO_2 and commercially available reference pure TiO_2 (ST-01), respectively. The anatase phase of Ti_(1-2X)Nb_XSc_XO_2 (X = 0-0.2) existed stably up to 900 ℃ during heat treatment in air. New rutile-type Ti_(1-2X)Nb_XSc_XO_2 solid solutions are formed through the phase transformation. The starting temperature of anatase-to-rutile phase transformation for Ti_(1-2X)Nb_XSc_XO_2 (X = 0-0.2) solid solutions was delayed but its completing temperature was accelerated.