The Crystal Disorder into ZnO with Addition of Bromine and It’s Outperform Role in the Photodegradation of Methylene Blue

In this research work, bromine (Br) is successfully doped into ZnO nanostructures using solvothermal method. The morphology, crystalline features, and composition of Br doped ZnO nanostructures were studied by scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive X ray spectroscopy (EDX) respectively. These newly prepared nanostructured materials were tested as photocatalysts for the photodegradation of methylene blue (MB) in aqueous solution under UV light. The kinetic rate constants were observed in the order (20% Br/ZnO > 15% Br/ZnO > 10% Br/ZnO > 5% Br/ZnO >pristine ZnO), thus they are indicating that the increasing Br dopant level has linear effect on the photodegradation of MB. The photocatalytic degradation efficiency of 60% was achieved for the pristine ZnO during the irradiation of UV light for 5 h, however 20% Br doped ZnO nanostructures has shown enhanced degradation efficiency of 97.63% during the irradiation of UV light for short interval of time of 2.2 h. The 20% Br/ZnO describes the highest rate constant value of (24.13 × 10 −3 min −1 ), for time period of 2.2 h and this values is about 8 and 4 times higher than the pristine ZnO (3.72 × 10 −3 min −1 ) and 5% Br/ZnO (6.13 × 10 −3 min −1 ), respectively. The obtained results of 20% Br doped ZnO sample are superior or equal in performance than the recently reported works. The catalytic mechanism is also proposed and it indicates the role of electrons coming from the bromine ion might act as radical for the degradation of MB. The present approach is simpler, environment friendly, scalable and could be of great consideration for the diverse energy and environment related applications. Graphic Abstract