Cerium and europium doped TiO2 thin films deposited by a sol-gel dip-coating process: characterization and photocatalytic activity toward dye degradation

Abstract

Cerium (Ce) and europium (Eu)-doped TiO2 thin films were obtained by sol-gel dip-coating technique. SEM micrographs showed that the surfaces are covered by agglomerated particles due to the repeating coating process. XRD patterns showed the presence of TiO2 anatase phase. Raman spectra revealed that the peaks recorded at 146 cm-1(Eg) and 397 cm-1(B1g) were related to the anatase phase. EIS measurements proved that Ce-TiO2 (1wt%) and Eu-TiO2 (0.1wt%) photocatalysts possessed a lower electron transfer resistance than pure TiO2, which can lead to effective separation of electron/ hole pairs during the photoreactions. The photoactivity of Ce and Eu-doped TiO2 was investigated by the degradation of amido black10B dye (AB) under UV excitation and varying the initial pH and concentrations. It was found that Eu-TiO2 (0.1wt%) exhibited higher photocatalytic activity, reaching a first-order reaction rate of kapp(0.036min-1), t1/2 was around 12 min and AB removal was 98.94%, under optimal pH of 3.5 and AB concentration of 10ppm compared to (t1/2 = 45 min, t1/2=30 min), (kapp = 0.022 min-1, kapp = 0.026min-1) and AB removal (94.78%, 96.44%), respectively for pure TiO2 and Ce-TiO2 (1wt%). Further increase in Eu/Ce amount up to optimal concentration (1wt% Ce and 0.1wt% Eu) led to a decrease in the AB removal. The mineralization of AB using Eu-TiO2 photocatalyst was confirmed by HPLC analysis.