Centre of Excellence in Environmental Studies (CEES), King Abdulaziz University, Jeddah, 21589, Saudi Arabia.
Department of Chemistry, Forman Christian College (A Chartered University), Ferozepur Road, Lahore, 54600, Pakistan.
Chemosphere. 2022 Feb;289:133092. doi: 10.1016/j.chemosphere.2021.133092. Epub 2021 Nov 29.
In order to enhance the photocatalytic performance and stability, the various proportions of the size controlled cerium oxide (CeO) nanoparticles were dispersed at the pre-synthesized ZnO. Although, the expected dual absorption onsets, probably due to the diminutive difference between the bandgaps of CeO (∼2.9 eV) and ZnO (∼3.1 eV), were not observed however, a blue shift in the bandgap energy of ZnO was witnessed with the increasing surface density of CeO particles. The delayed excitons recombination process with the increasing concentration of CeO nanoparticles was verified by the PL spectra. The structural investigation by Raman and XRD analysis revealed the surface attachment of CeO particles without altering the rock-salt lattice of ZnO. The morphological and fine microstructural analysis established the uniform distribution of evenly sized CeO particles at the surface of ZnO with the discrete fringe patterns of both the entities whereas the XPS analysis confirmed the majority of Ce in dispersed CeO. In comparison to pure ZnO, cyclic voltammetric (CV) analysis, under illumination, exposed the supportive role of surface residing CeO particles in eradicating the photo-corrosion of ZnO whereas the chronopotentiometry (CP) predicted the prolonged life-span of the excitons. Compared to pure ZnO, an appreciably high activity was revealed for 10% CeO loading as compared to pure ZnO for the removal of mono and di-nitrophenol derivatives and their mixtures under natural sunlight exposure. The variations in the removal rates in the mixture as compared to individual nitrophenol exposed the structure-based priority of ROS for the respective phenol. The significantly enhanced photocatalytic activity of the composite catalysts revealed the incremental role of surface-mounted CeO entities in boosting the generation of ROS under sunlight irradiation. The experimental observations were correlated and compiled to establish the mechanism of the removal process.
为了提高光催化性能和稳定性，将不同比例的尺寸可控氧化铈（CeO）纳米颗粒分散在预先合成的 ZnO 上。尽管预期的双吸收起始点，可能由于 CeO（约 2.9 eV）和 ZnO（约 3.1 eV）的能带隙之间的微小差异而没有观察到，但随着 CeO 颗粒表面密度的增加，观察到 ZnO 的能带隙能量发生蓝移。通过 PL 光谱证实了随着 CeO 纳米粒子浓度的增加，激子复合过程延迟。拉曼和 XRD 分析的结构研究表明，CeO 颗粒表面附着而不改变 ZnO 的岩盐晶格。形态和微观结构分析表明，CeO 颗粒均匀分布在 ZnO 表面，具有均匀尺寸的离散条纹图案，而 XPS 分析证实了分散的 CeO 中的 Ce 主要以 CeO 存在。与纯 ZnO 相比，循环伏安（CV）分析表明，在光照下，表面存在的 CeO 颗粒在消除 ZnO 的光腐蚀方面发挥了支持作用，而恒电流（CP）预测了激子的寿命延长。与纯 ZnO 相比，10%CeO 负载的复合催化剂在去除单硝基和二硝基酚衍生物及其混合物方面表现出明显高于纯 ZnO 的活性，与纯 ZnO 相比，在自然光照射下，混合物的去除率的变化暴露了 ROS 对各自酚类的基于结构的优先性。复合催化剂的光催化活性显著增强，表明表面安装的 CeO 颗粒在阳光照射下产生 ROS 方面发挥了增量作用。对实验观察结果进行了相关和编译，以建立去除过程的机制。
