Photocatalytic degradation of naphthalene on CeVO4 nanoparticles under visible light

Various morphologies and structure properties of CeVO4 photocatalysts were prepared via ethylene glycol (EG)-aided hydrothermal method and characterized by XRD, SEM, EDX, TEM, XPS, UV-Vis diffuse reflectance, PL emission and transient photocurrent responses, respectively. The influence of EG content on morphology and structure of as-prepared samples was examined as regard the photodegradation performance of naphthalene (Nap) in natural seawater. The results showed that Ce2 (CeVO4) sample with 10 mL EG addition exhibited the highest photodegradation efficiency of Nap, because the fusiform morphology of Ce2 sample favored the transportation of visible light and the separation of photoexcited carriers. In addition, the possible intermediate products were detected by FTIR, 3D fluorescence and GC-MS and the results showed only one mechanism of Nap direct conversion to CO2 and H2O was include in the photocatalytic reaction by Ce2 sample. The active species were detected by ESR and trapping experiments and the results showed that center dot OH played a more significant role in the photochemical degradation. Finally, the possible photodegradation mechanism of Nap over Ce2 sample was proposed on the basis of intermediate products and the active species formed in photodegradation process, and Ce-4(+)/Ce-3(+) redox centers of Ce2 sample was performed under the irradiation of visible light.

采用乙二醇（EG）辅助水热法制备了具有不同形貌和结构特性的CeVO₄光催化剂，并分别通过X射线衍射（XRD）、扫描电子显微镜（SEM）、能谱分析（EDX）、透射电子显微镜（TEM）、X射线光电子能谱（XPS）、紫外 - 可见漫反射光谱、光致发光发射光谱以及瞬态光电流响应进行了表征。考察了EG含量对所制备样品的形貌和结构的影响，并研究了其对天然海水中萘（Nap）的光降解性能。结果表明，添加10 mL EG的Ce₂（CeVO₄）样品对萘表现出最高的光降解效率，这是因为Ce₂样品的梭形形貌有利于可见光的传输以及光生载流子的分离。此外，通过傅里叶变换红外光谱（FTIR）、三维荧光光谱和气相色谱 - 质谱联用（GC - MS）检测了可能的中间产物，结果表明Ce₂样品的光催化反应仅包含萘直接转化为CO₂和H₂O这一种机制。通过电子自旋共振（ESR）和捕获实验检测了活性物种，结果表明·OH在光化学降解中起更重要的作用。最后，根据光降解过程中形成的中间产物和活性物种，提出了Ce₂样品上萘可能的光降解机制，并且Ce₂样品的Ce⁴⁺/Ce³⁺氧化还原中心在可见光照射下发挥作用。