Photocatalytic Performance of Undoped and Al-Doped ZnO Nanoparticles in the Degradation of Rhodamine B under UV-Visible Light:The Role of Defects and Morphology

Abstract

Quasi-spherical undoped ZnO and Al-doped ZnO nanoparticles with different aluminum content, ranging from 0.5 to 5 at% of Al with respect to Zn, were synthesized. These nanoparticles were evaluated as photocatalysts in the photodegradation of the Rhodamine B (RhB) dye aqueous solution under UV-visible light irradiation. The undoped ZnO nanopowder annealed at 400 °C resulted in the highest degradation efficiency of ca. 81% after 4 h under green light irradiation (525 nm), in the presence of 5 mg of catalyst. The samples were characterized using ICP-OES, PXRD, TEM, FT-IR, 27Al-MAS NMR, UV-Vis and steady-state PL. The effect of Al-doping on the phase structure, shape and particle size was also investigated. Additional information arose from the annealed nanomaterials under dynamic N2 at different temperatures (400 and 550 °C). The position of aluminum in the ZnO lattice was identified by means of 27Al-MAS NMR. FT-IR gave further information about the type of tetrahedral sites occupied by aluminum. Photoluminescence showed that the insertion of dopant increases the oxygen vacancies reducing the peroxide-like species responsible for photocatalysis. The annealing temperature helps increase the number of red-emitting centers up to 400 °C, while at 550 °C, the photocatalytic performance drops due to the aggregation tendency.

Quasi‐Diamond Platelet‐Shaped Zinc Oxide Nanostructures Display Enhanced Antibacterial Activity

“…Both stacked particles exhibited similar average stacked sizes. Previous reports suggest that spherical ZnO nanoparticles tend to agglomerate into larger particles when a heat treatment is applied [14,40,41] . Sayed et al.…”

“…Previous reports suggest that spherical ZnO nanoparticles tend to agglomerate into larger particles when a heat treatment is applied. [14,40,41] Sayed et al reported a morphologic study related to nanostructures with antibacterial activity. These authors suggest platelets with diamond-type-shape showing the highest antibacterial activity, compared to the large platelets and spherical structures.…”

Optimization of ZnO Nanoparticles’ Synthesis via Precipitation Method Applying Taguchi Robust Design

“…The remaining half of the tetrahedral sites and all octahedral sites remain unoccupied. Undoped ZnO exhibits n-type conductivity, which is commonly attributed to inherent defects such as excess zinc at interstitial positions and oxygen deficiencies [15].…”

Recent Advances in Synthesis, Characterization and Applications of Innovative Materials in Removal of Water Contaminants

“…In this Special Issue, Piras et al reported the influence of the defects and morphology of undoped and Al-doped ZnO nanoparticles on the photocatalytic degradation efficiency of Rhodamine B under UV-Visible [20]. The undoped ZnO nanopowder, annealed at 400 • C, resulted in the highest degradation efficiency of ca.…”

“…The undoped ZnO nanopowder, annealed at 400 • C, resulted in the highest degradation efficiency of ca. 81% after 4 h under green light irradiation (525 nm) in the presence of 5 mg of catalyst [20]. Photoluminescence showed that the insertion of a dopant increases the oxygen vacancies, reducing the peroxide-like species responsible for photocatalysis [20].…”