Abstract

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

中文翻译：

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溴加成导致ZnO晶体失序及其在亚甲基蓝光降解中的作用

摘要

在这项研究工作中，使用溶剂热法将溴（Br）成功地掺杂到了ZnO纳米结构中。分别通过扫描电子显微镜（SEM），X射线衍射（XRD）和能量色散X射线光谱（EDX）研究了掺Br的ZnO纳米结构的形态，晶体特征和组成。这些新制备的纳米结构材料已作为光催化剂在紫外光下用于水溶液中亚甲基蓝（MB）的光降解测试。观察到动力学速率常数的顺序为（20％Br / ZnO> 15％Br / ZnO> 10％Br / ZnO> 5％Br / ZnO>原始ZnO），因此它们表明增加的Br掺杂水平呈线性对MB的光降解有影响。原始ZnO在紫外线照射5h时达到60％的光催化降解率，然而，掺有20％Br的ZnO纳米结构在2.2 h的短时间内照射紫外线时，降解效率提高了97.63％。20％Br / ZnO表示最高速率常数值（24.13×10^-3 min ^-1），持续时间为2.2 h，该值分别是原始ZnO（3.72×10 ^-3 min ^-1）和5％Br / ZnO（6.13×10 ^-3 min ）的约8倍和4倍^-1）。20％Br掺杂的ZnO样品的结果优于或等于最近报道的工作。还提出了催化机制，它表明来自溴离子的电子的作用可能充当自由基降解MB。本方法是更简单，环境友好，可扩展的，并且对于与能源和环境相关的各种应用可能是非常重要的考虑因素。

图形摘要