Simultaneous Controlled Seeded-Growth and Doping of ZnO Nanorods with Aluminum and Cerium: Feasibility Assessment and Effect on Photocatalytic Activity

Doped and undoped ZnO nanorods (ZnO-NRs) are highly investigated materials for their numerous applications in catalysis, in optoelectronics, and in analytical chemistry. Seeded growth using well-defined ZnO nanomaterials represents a useful approach to control the size and morphology of undoped ZnO-NRs; however, the possibility to use such a strategy to produce size-defined doped ZnO-NRs was not previously investigated. In this work, we show that it is possible to prepare aluminum- A nd cerium-doped ZnO-NRs with well-defined length and diameter by a controlled hydrolytic seeded growth. The synthesized materials were characterized by various analytical techniques such as XPS, EDS, SEM/EDS, XRD, Raman, UV-vis, and photoluminescence (PL), which evidenced the correlation between the loading of dopant, the morphology of the nanorods, their optoelectronic properties, and the amount and nature of lattice defects. Given its smaller ionic radius, the doping with aluminum was more efficient than with cerium. Indeed, for the latter element, dopant concentrations above a certain threshold led to phase separation and coprecipitation of ceria particles during synthesis. In addition, the effect of our preparation strategy on the photocatalytic activity of doped and undoped ZnO-NRs was investigated by studying the photodegradation of methyl orange (MO) under UV light. The study revealed that aluminum-doped ZnO-NRs generally performed better than cerium-doped ZnO-NRs and that moderate aluminum concentrations could lead to an improvement of the photocatalytic performance compared to undoped ZnO-NRs, an observation that could be related to the occurrence and abundance of specific defect sites in the lattice.