Selenium Zinc Oxide (Se/ZnO) Nanoparticles: Synthesis, Characterization, and Photocatalytic Activity

A facile synthesis of undoped and 2.0 % selenium-doped zinc oxide nanoparticles (NPs) was efficaciously accomplished through a mechanochemical route using zinc acetate dihydrate, oxalic acid, and Se powder in a solid state reaction. After calcination at 450 °C, the obtained nanostructures were probed by X-ray diffraction, where the acquired data revealed the pertinence of the wurtzite hexagonal ZnO for both undoped (ZnO) and doped (Se/ZnO) NPs and crystallite sizes of 30 and 24 nm for ZnO and Se/ZnO, respectively. The formation of the target NPs was confirmed by the scanning and transmission electron microscopy, energy-dispersive X-ray analysis, and the Fourier transformation infrared molecular vibrations data. The porosity investigations indicated 33.65 m²/g Brunauer–Emmett–Teller surface area, 197 Å pore diameter, and 0.172 cm³/g pore volume for the Se/ZnO NPs compared to lower values for the pristine ZnO. The band gap energies were 3.19 and 3.15 eV for ZnO and Se/ZnO as perceived from the Tauc plots of the UV-visible absorption measurements. The photodegradation of methylene blue dye under UV illumination was found to follow the pseudo–first-order kinetics with an enhanced performance by the doped samples as reflected by the higher (3.2 × 10⁻³ s⁻¹) rate constant relative to the undoped sample (1.7 × 10⁻³ s⁻¹). A photodegradation mechanism was suggested in the light of the band gap energy investigation. The obtained findings indicate the improvement of ZnO properties by doping with Se through a simplistic and inexpensive approach.