Impact on the Photocatalytic Dye Degradation of Morphology and Annealing-Induced Defects in Zinc Oxide Nanostructures

In this study, three different morphologies, nanoflower (NF), nano sponge (NS), and nano urchin (NU), of zinc oxide (ZnO) nanostructures were synthesized successfully via a mild hydrothermal method. After synthesis, the samples were annealed in the atmosphere at 300, 600, and 800 ?. Although annealing provides different degradation kinetics for different morphologies, ZnO NS performed significantly better than other morphologies for all annealing temperatures we used in the study. When the photoluminescence, electron paramagnetic resonance spectroscopy, BET surface, and X-ray diffraction analysis results are examined, it is revealed that the defect structure, pore diameter, and crystallinity cumulatively affect the photocatalytic activity of ZnO nanocatalysts. As a result, to obtain high photocatalytic activity in rhodamine B (RhB) degradation, it is necessary to develop a ZnO catalyst with fewer core defects, more oxygen vacancies, near band emission, large crystallite size, and large pore diameter. The ZnO NS-800 ? nanocatalyst studied here had a 35.6 x 10(-3) min(-1) rate constant and excellent stability after a 5-cycle photocatalytic degradation of RhB.

Automated summary

Three different morphologies of ZnO nanostructures, nanoflower (NF), nano sponge (NS), and nano urchin (NU), were successfully synthesized via a mild hydrothermal method. Annealing at different temperatures showed that ZnO NS performed significantly better in terms of degradation kinetics compared to the other morphologies. The photocatalytic activity of ZnO nanocatalysts was found to be influenced by defect structure, pore diameter, and crystallinity. The ZnO NS-800 ? nanocatalyst exhibited a rate constant of 35.6 x 10(-3) min(-1) and excellent stability after a 5-cycle photocatalytic degradation of RhB.