0.7 mol% Er-TiO2 nanotubes were prepared using a sol-gel derived electrospinning and subsequent calcination at intervals of 50 oC from 500 oC to 650 oC to investigate the effect of calcination temperature on the crystal structure and the photocatalytic activity of methylene blue (MB). X-ray diffraction (XRD) results indicated that Er-TiO2 nanotubes calcined at 500 oC were composed of anatase only. However, mixed phases of anatase (51%, 55%, 96%) and rutile (49%, 45%, 4%) were observed for the nanotubes calcined at 550 oC, 600 oC and 650 oC, respectively. As the calcination temperature rose from 500 oC to 600 oC, the Barrette-Emmett-Teller (BET) surface area and degradation kinetic constant increased from 97.77 m2/g to 117.62 m2/g and from 1.2 × 10−2 min−1 to 1.6 × 10-2 min-1, respectively. The Er-TiO2 nanotubes calcined at 600 oC exhibited enhanced MB degradation (87%) compared to that of Er-TiO2 nanofibers (37%) due to the synergic combinations of tailored mixed crystals and larger BET area.
Keywords: Er-doped TiO2, Electrospinning, Nanotube, Methylene blue, Photodegradation