Cerium- and Europium-Doped Titanium Nanotube Arrays: Synthesis and Photoelectrochemical Activity

Cerium- and Europium-doped titanium nanotube (Ce and Eu-TNTs) were obtained by one-step electrochemical anodization. The arrays were characterized by SEM–EDS, X-ray diffraction (XRD) and Raman spectroscopy. The results show that pure TNTs, Ce-TNTs and Eu-TNTs thin films exhibit (101) XRD peak corresponding to the TiO₂ anatase phase. The latter is consistent with the recorded Raman signal observed at 143 cm⁻¹ (Eg mode) and 394 cm (B_1g mode), respectively. The morphology and surface studies reveal a nanotubular structure. The photoactivity of Ce- and Eu-doped TNTs was evaluated by a comparison of the photoelectric behaviors in an alkaline medium. EIS plots indicated that doped TNT photocatalyst possesses a lower electron transfer resistance than pure TNTs, which can lead to an effective separation of photogenerated electron/hole pairs. Under optimal conditions, a maximum photodegradation efficiency of AB dye, as pollutant model, was achieved at pH = 3, reaching about 94.79% and 96.77% respectively for Eu-TNTs (2mM) and Ce-TNTs.