Study on the Influence of Ni Modifying on Phase Transformation and Photocatalytic Activity of TiO2

The Ni-modified TiO2 was synthesized using two methods including co-precipitation (Ni doped TiO2, Ni-TiO2) and wet impregnation (Ni loaded TiO2, Ni/TiO2). The surface and bulk crystalline phases of Ni-modified TiO2 were investigated by using X-ray diffractometry (XRD), UV Raman spectroscopy, TEM, and SEM. It is observed that Ni doping can promote the phase transition and grain size growth of TiO2. Moreover, the propagation of the rutile phase from the bulk into the surface region of TiO2 is increased when the Ni doping amount reaches up to 3%. However, in Ni/TiO2, it is found out that the surface and bulk phase transformation of TiO2 can be inhibited after impregnation of 1% of Ni on the TiO2. Compared with the co-precipitation method, Ni species may be more enriched in the surface of the Ni/TiO2 sample upon adoption of the impregnation method, and the direct contact of anatase particles of TiO2 is avoided. As a consequence, the phase transition in the surface and bulk region of TiO2 can be effectively inhibited by Ni loading. Additionally, the activity of the photocatalytic degradation of RhB on the 3Ni-TiO2-600 degrees C sample is higher than that on the 3 Ni/TiO2-600 degrees C sample. The phase junction formed between anatase and rutile in the surface region of 3Ni-TiO2-600 degrees C may the main reason for its high photocatalytic activity.