The Role of Pluronic Copolymer on the Physicochemical Characteristics of ZnO-CeO2 Photocatalysts

CeO2-ZnO nanocrystalline powders were prepared using Pluronic-assisted precipitation, followed by calcination at 500 °C. Different amounts of tri-block Pluronic copolymer (P123—2.5 g (P2.5), 5 g (P5), and 0 g (P0)) were used. PXRD, XPS, TEM, EDS, DRS, EPR, FT-IR spectroscopy, and the BET method were performed to determine the physicochemical characteristics of the prepared samples. They showed that the increased amount of P123 leads to an increased degree of crystallinity and polarity. The addition of the polymer in appropriate quantity plays a role as a structure-directing agent, thus preventing agglomeration processes and leading to changes in the structural features of the composites, which result in an increase in the band gap values. The adsorption edges of P0, P2.5, and P5 are 389.5 nm, 386.2 nm, and ~385.3 nm, which prove a blue shift. The photocatalytic discoloration of the Reactive Black 5 dye in the presence of all powders under UV-A illumination was studied. The P5 powder possessed the highest degree of discoloration (86% for 2 h illumination). These results could be assigned to the increased band gap value, polarity, and degree of crystallinity, as well as the increased quantity of Ce3+, oxygen vacancies, and hydroxyl groups of the Pluronic-modified powders.