| 저자(한글) |
Meksi, M.,Turki, A.,Kochkar, H.,Bousselmi, L.,Guillard, C.,Berhault, G. |
| 초록 |
The influence of lanthanum on the thermal stability and photocatalytic activity of calcined hydrogenotitanate nanotubes (HNT) was herein evaluated. HNT samples were prepared through the hydrothermal treatment of TiO 2 P25 in a concentrated NaOH solution (11.25M) at 130 o C during 20h followed by acid washing. La-doped titanates nanotubes (La-HNT) photocatalysts with optimum 1wt% of La were then elaborated by incipient wetness impregnation method using lanthanum nitrate as precursor. La-HNT and HNT samples were then calcined at temperatures varying between 400 o C and 700 o C. Samples were characterized by means of nitrogen adsorption-desorption isotherms at 77K, X-ray diffraction (XRD), Raman spectroscopy, diffuse reflectance spectroscopy (DRS), photoluminescence spectroscopy (PL), transmission electron microscopy (TEM), ICP analysis and photocurrent experiments. The photocatalytic activities of La-HNT and HNT derived nanomaterials were then evaluated through the photocatalytic degradation of formic acid (FA). Main results reveal that lanthanum inhibits TiO 2 crystallite growth and retards anatase transformation into the less active rutile phase. The addition of La ions to TiO 2 results in a charge imbalance creating a high proportion of oxygen vacancies as evidenced by photocurrent, photoluminescence and Raman experiments. The photocatalytic experiments reveal that La-doped TiO 2 helps to maintain a high photocatalytic activity level even after calcination at high temperatures contrary to La-free photocatalysts. The determination of kinetic parameters reveals that the maintaining of a high photocatalytic activity results from the synergetic effect between restriction of TiO 2 crystallite size growth and formation of a high proportion of oxygen vacancies. |
