Enhanced photocatalytic and photoelectrochemical investigation of Ce and Eu modified titanium nanotube arrays towards dye removal

Abstract

ABSTRACT Cerium and europium-doped titanium nanotube (Ce and Eu-TNTs) were obtained by one-step electrochemical anodization. SEM micrographs show highly ordered nanotubes for pure- TNTs but less organized and more spaced nanotubes for Ce and Eu-TNTs. The XRD results show that anatase is the dominant phase, and the doping does not change the crystalline phase. EIS plots indicated that Ce/Eu doped TNTs photocatalysts possesses a lower electron transfer resistance than pure TNTs, which is related to an effective separation of photogenerated electron/hole pairs. The photodegradation results showed that Ce-TNTs (0.5 mM) and Eu-TNTs (2 mM) photocatalysts exhibit the best enhancement of AB removal reaching a reaction rate of (kapp = 0.026 min−1, t1/2 = 19 min) and (kapp = 0.020 min−1, t1/2 = 20 min), respectively, under initial pH = 3 and CAB = 10 mg.L−1, compared to (kapp = 0.014 min−1, t1/2 = 35 min) for pure TNTs. The adsorption efficiency carried out in the dark after 30 min is enhanced by Ce and Eu-doping and reaches its maximum to 52.08% for Eu-TNTs (2 mM) compared to only (31.11% and 32.96%), respectively, for Ce-TNTs (0.5 mM) and pure TNTs catalyst. Graphical Abstract