Cerium oxide (CeO2) is of particular interest as a photocatalyst due in part to the low redox potential between Ce3+ and Ce4+ in the solid state and the subsequent creation of oxygen vacancies in the lattice. The addition of europium (as Eu3+) further increases the oxygen vacancies in the lattice, potentially increasing catalytic activity, while also adding a fluorescent tag to the nanomaterial. The combination of these features makes europium-doped cerium oxide (EuCeO2) nanomaterials an interesting candidate for investigation. In this work, a series of europium-doped and undoped cerium oxide nanomaterials were synthesized via a hydrothermal reaction to compare the effect of morphology on nanomaterial-mediated dye remediation. These morphologies include rods, annealed rods, cubes, and needles, with the materials characterized using transmission electron microscopy (TEM), energy dispersive x-ray spectroscopy (EDAX), and powder x-ray diffraction (XRD). Dye degradation is often used to test a material’s ability as a photocatalyst, in addition to potential environmental uses to remedy water pollution by dyes. As such, the photocatalytic and adsorption capabilities of the characterized EuCeO2 and CeO2 materials were evaluated through dye degradation, using malachite green as a model dye. There is significant literature on dye degradation by cerium oxide, as well as the degradation of malachite green by other semiconductor materials. However, few specifically examine the degradation of malachite green by cerium oxide and most experiments are limited to spherical nanoparticles. UV-Vis spectroscopy was used to measure the decrease in dye-associated absorbance due to dye adsorption and photolytic degradation following irradiation by a tungsten-halogen lamp. The addition of EuCeO2 nanorods resulted in a 73% decrease in dye concentration, of which 58% and 15% were due to adsorption and degradation after irradiation, respectively. Annealing these nanorods lowered their effectiveness with an overall 56% decrease, with 46% due to adsorption and 10% due to degradation. Nanocubes showed comparable results to the annealed nanorods, but at one fifth the catalyst loading. The nanoneedles, while not exhibiting notable photocatalytic activity, removed over 85% of the dye, the highest of all materials. In comparing cerium oxide materials with their europium-doped counterparts, it was found that the addition of europium does not affect the photocatalytic activity of the materials.

Europium-doped cerium oxide nanomaterials for the photocatalytic degradation of malachite green

2019 Spring National Meeting

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