Tuning the morphologies of ZnO for enhanced photocatalytic activity

Facile one-pot method to prepare three-dimensional hierarchical nanostructures of ZnO with good control over their morphologies and enhanced photocatalytic activity was developed by proper selection of template, base and microwave irradiation conditions in pure water. Synthesized ZnO products were characterized by XRD, SEM, BET, and TGA. The effect of morphology on the decolorization of Rhodamine B solution under UV light irradiation was investigated. The ZnO nanorods originating from the center (Tetrapods) exhibits enhanced photocatalytic activity in the degradation of Rhodamine B under UV light irradiation. This high degradation efficiency (98.86 %) can be attributed to the large percentage of the exposed [101] facet, (facet dependent) even though surface area is relatively lower. Photocatalytic study reveals that the decomposition of Rhodamine B follows a first order kinetics regardless of the morphology of ZnO particles. The rate constant for nano tetrapods of ZnO particles is the highest (0.036 min-1), while the rate constant for nano coral reefs is lowest (0.003 min-1). Moreover, the photocatalyst exhibits excellent durability, allowing it to be utilized for at least five consecutive cycles without losing its efficiency. Based on the results obtained from two separate synthesis and characterization experiments performed under identical reaction conditions, we can conclude that our material and synthesis protocol exhibit a high degree of reproducibility. This study signifies the dependence of enhanced photocatalytic activity on morphology but not the surface area of material.