Effect of induced defects on the properties of ZnO nanocrystals: surfactant role and spectroscopic analysis

Semiconductor photocatalysts are one of the major sought area of research due to their extensive use in the degradation of organic pollutants under UV-visible and solar light. Herein, we are reporting the synthesis of microscopic spindle shaped ZnO photocatalysts with different reducing agents such as sodium hydroxide, hydrazine hydride, sodium borohydride and lithium triethyl borohydride. These spindle shaped ZnO are synthesized by facile soft chemical approach by varying reducing agents with fixed molar ratio at 1:2 zinc precursor to reducing agents. These ZnOs were thoroughly characterised by various sophisticated characterization techniques such as XRD, FTIR, SEM, and HRTEM, Raman and ESR spectroscopies. Microscopic results show that these ZnO show similar fusiform morphologies with the variation in sizes and their distributions, and hence possess different defect related properties. The structural growth mechanism and defect related properties were explained on the basis of different reducing abilities of reducing agents (different reaction pH) and their nucleation with the aid of morphological analysis, and ESR analysis. Furthermore, the photocatalytic activity of these spindle shaped ZnO were evaluated against two cationic dyes (methylene blue dyes, Rhoda mine B) under UV light. The photocatalytic results show that these spindle shaped ZnO are very effective for the photo-catalytic degradation of methylene blue and rhodamine B dye under the illumination of UV light.