Vishwanathan Shalini, Das Susmita
Department of Chemical Engineering, National Institute of Technology Calicut, Calicut, 673601, India.
Environ Sci Pollut Res Int. 2023 Jan;30(4):8512-8525. doi: 10.1007/s11356-022-20283-1. Epub 2022 Apr 23.
Glucose -mediated one-pot hydrothermal method has been utilized to synthesize hollow spherical MgO-ZnO (MgO-ZnO, x = 0, 0.2, 0.4, 0.6) microstructures which are highly efficient in high-energy ultraviolet (UV) region of natural sunlight. In this process, glucose formed roundish spheres, and simultaneously metal precursors were coated on that spheres during the hydrothermal reaction. X-ray diffraction analysis (XRD) supports the formation of highly crystalline wurtzite structure of MgO-ZnO for Mg loading less than 20%. Higher concentration of Mg produces wurtzite hexagonal ZnO and cubic MgO in the composites. The widening in band gap energy of synthesized MgO-ZnO microspheres compared to ZnO was analyzed by UV-visible diffuse reflectance spectroscopy (UV-DRS) result. Brunauer-Emmett-Teller (BET) surface area analysis showed that with the increase in Mg loading, the specific surface area increases up to 14.27 times as compared to pristine ZnO. The synthesized catalysts were used as an efficient photocatalyst towards the degradation of rhodamine B (RhB), methylene blue (MB), and phenol under natural solar irradiation. Results illustrated that MB and RhB dye solutions were 100% degraded by 0.6 MgO-ZnO in 100 min and 150 min, respectively, whereas pure ZnO samples showed only 65% and 79% degradation. Also, for phenol solution, 0.6 MgO-ZnO showed enhanced degradation efficiency of 72% in 240 min in comparison with 58% degradation shown by ZnO. Additionally, the MgO-ZnO catalysts were stable and showed excellent degradation efficiency up to four consecutive cycles which open a new direction towards potential industrial applications. Hence, the novelty of the current work is to prepare hollow MgO-ZnO microspheres by a single-step hydrothermal process where separate carbon template preparation is not required and to utilize these hollow microspheres as a highly efficient photocatalyst by harnessing the high-energy UV fraction of natural sunlight.
葡萄糖介导的一锅水热法已被用于合成空心球形的MgO-ZnO（MgO-ZnO，x = 0、0.2、0.4、0.6）微结构，这些微结构在自然阳光的高能紫外（UV）区域具有高效性。在此过程中，葡萄糖形成圆形球体，同时在水热反应期间金属前驱体被包覆在这些球体上。X射线衍射分析（XRD）支持对于镁负载量小于20%的MgO-ZnO形成高度结晶的纤锌矿结构。较高浓度的镁在复合材料中产生纤锌矿六方ZnO和立方MgO。通过紫外-可见漫反射光谱（UV-DRS）结果分析了合成的MgO-ZnO微球与ZnO相比带隙能量的拓宽情况。布鲁诺尔-埃米特-特勒（BET）表面积分析表明，随着镁负载量的增加，比表面积相比于原始ZnO增加了高达14.27倍。合成的催化剂被用作在自然太阳光照射下对罗丹明B（RhB）、亚甲基蓝（MB）和苯酚降解的高效光催化剂。结果表明，MB和RhB染料溶液分别在100分钟和150分钟内被0.6MgO-ZnO完全降解，而纯ZnO样品仅显示65%和79%的降解率。此外，对于苯酚溶液，0.6MgO-ZnO在240分钟内显示出72%的增强降解效率，相比之下ZnO显示出58%的降解率。此外，MgO-ZnO催化剂稳定，并且在连续四个循环中均表现出优异的降解效率，这为潜在的工业应用开辟了新方向。因此，当前工作的新颖之处在于通过一步水热法制备空心MgO-ZnO微球，其中不需要单独制备碳模板，并通过利用自然太阳光的高能紫外部分将这些空心微球用作高效光催化剂。
