Photocatalytic Nb2O5-doped TiO2 nanoparticles for glazed ceramic tiles

Abstract TiO 2 nanoparticles are currently used as coating for self-cleaning building products. In order to achieve high self-cleaning efficiency for outdoor applications, it is important that titania is present as anatase phase. Moreover, it is desirable that the particle sizes are in nano-range, so that a large enough surface area is available for enhanced catalytic performance. In this work, TiO 2 nanoparticles doped with 0–5 mol% Nb 2 O 5 were synthesized by co-precipitation. Nb 2 O 5 postponed the anatase to rutile transformation of TiO 2 by about 200 °C, such that after calcination at 700 °C, no rutile was detected for 5 mol% Nb 2 O 5 -doped TiO 2 , while undoped TiO 2 presented 90 wt% of the rutile phase. A systematic decreasing on crystallite size and increasing on specific surface area of TiO 2 were observed with higher concentration of Nb 2 O 5 dopant. Photocatalytic activity of anatase polymorph was measured by the decomposition rate of methylene blue under ultraviolet and daylight illumination and compared to commercial standard catalyst (P25). The results showed enhanced catalysis under UV and visible light for Nb 2 O 5 -doped TiO 2 as compared to pure TiO 2 . In addition, 5 mol% Nb 2 O 5 -doped TiO 2 presented higher photocatalytic activity than P25 under visible light. The enhanced performance was attributed to surface chemistry change associated with a slight shift in the band gap.