Photo-degradation of organic dye by zinc oxide nanosystems with special defect structure: Effect of the morphology and annealing temperature

• The super active ZnO catalysts developed for photo-degradation of organic dye.
• ZnO photocatalysts were analyzed by SEM, TEM, DLS, XRD, PLS, BET, CHN methods.
• Effect of annealing temperature and morphology in photo-oxidation were probed.
• Only interstitial zinc and oxygen vacancy are effective in photo-degradation.
• The interstitial oxygen and zinc vacancy have negligible efficacy in degradation.

The fabrication of strong photocatalysts applied to the degradation of organic pollutants is necessary in environmental applications. In a single-stage method, acetate precursor and poly vinyl pyrolydine are used to produce ZnO nanostructures with various morphologies in annealing temperatures ranging from 300 to 900 °C. The physical properties of the prepared nanostructures were characterized by SEM, TEM, XRD, BET, DRS, CHN analysis and PL spectroscopy. The SEM images exhibit a variety of the as-prepared hexagonal zinc oxides including wires, rods, particles and porous network of welded particles of ZnO nanoparticles. The results of the photocatalytic degradation of methylene blue as an organic dye in aqueous suspension showed that the morphology of ZnO nanostructures influences on the photocatalytic efficiency of ZnO nanostructures, greatly. For the best result, the highest MB degradation occurs by ZnO nanowires within 16 min and in others samples, degradation of higher than 95% occurs within 20 min. The XRD and PL spectroscopy revealed neither VZn nor Oi are in all of samples but only VO−, VO2− and Zni exist in ZnO nanostructures.

The annealing temperature and morphology of ZnO oxide photocatalyst are effective in photo-oxidation of organic dye such as methylene blue. The ZnO nanowires are more active than ZnO nanoparticles and only interstitial zinc (Zni) and oxygen vacancy (VO) defects not interstitial oxygen (Oi) and zinc vacancy (VZn) defects are effective in photo-degradation.Figure optionsDownload high-quality image (150 K)Download as PowerPoint slide