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

Authors: DALANDA HAMDI, LOBNA MANSOURI, VARSHA SRIVASTAVA, MIKA SILLANPAA, LATIFA BOUSSELMI

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(E_g) and 397 cm^-1(B_1g) 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 k_app(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 (t_1/2 = 45 min, t_1/2=30 min), (k_app = 0.022 min^-1, k_app = 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.

Keywords: TiO₂, cerium, europium, sol-gel, dip coating, silicon, photodegradation

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