Atchudan Raji, Edison Thomas Nesakumar Jebakumar Immanuel, Mani Shanmugam, Perumal Suguna, Vinodh Rajangam, Thirunavukkarasu Somanathan, Lee Yong Rok
School of Chemical Engineering, Yeungnam University, Gyeongsan 38541, Republic of Korea.
Dalton Trans. 2020 Dec 22;49(48):17725-17736. doi: 10.1039/d0dt02756a.
Nitrogen-doped carbon dot decorated zinc oxide nanoparticles (N-CDs@ZnO composite) were successfully fabricated by an economical wet-impregnation method and used as a photocatalyst for the degradation of aqueous methylene blue (MB) dye under UV-light at room temperature. The chemical composition and morphological features of the prepared N-CDs@ZnO composite were characterized by attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and field emission scanning electron microscopy (FESEM). The photodegradation capability of the N-CDs@ZnO composite was compared with that of bare ZnO nanoparticles, under identical experimental conditions. The results show that the N-CDs@ZnO composite exhibits notably higher photocatalytic activity (degradation efficiency over 99%, 60 min) compared to bare ZnO nanoparticles (75%, 60 min) towards the degradation of MB under UV-light irradiation. Besides, the degradation obeyed the pseudo-first-order kinetics model with a photocatalytic rate constant (k) of 0.0557 min-1, which was ∼2.3 times higher than that of bare ZnO nanoparticles (0.0240 min-1). The crucial roles of N-CDs in the enhancement of the photocatalytic activity of the N-CDs@ZnO composite arise because the N-CDs can efficiently absorb UV-light and trap electrons, thus hindering the recombination of the photo-generated electron-hole pairs and also suppressing the photocorrosion of the ZnO nanoparticles in the N-CDs@ZnO composite. The N-CDs@ZnO composite not only showed good photocatalytic activity but also had good stability since the photocatalytic activity did not significantly decrease after three cycling tests. The present study shows that the N-CDs@ZnO composite can be considered as an ideal photocatalyst in the field of dye degradation. Overall, the present approach obeys green chemistry principles with the simple construction of the N-CDs@ZnO composite and the composite holds promise for the development of efficient photocatalytic systems.
通过经济的湿浸渍法成功制备了氮掺杂碳点修饰的氧化锌纳米颗粒（N-CDs@ZnO复合材料），并将其用作光催化剂，在室温下紫外光照射下降解水溶液中的亚甲基蓝（MB）染料。通过衰减全反射傅里叶变换红外（ATR-FTIR）光谱、X射线光电子能谱（XPS）、X射线衍射（XRD）和场发射扫描电子显微镜（FESEM）对制备的N-CDs@ZnO复合材料的化学成分和形态特征进行了表征。在相同实验条件下，将N-CDs@ZnO复合材料的光降解能力与裸氧化锌纳米颗粒的光降解能力进行了比较。结果表明，在紫外光照射下，与裸氧化锌纳米颗粒（60分钟内降解效率为75%）相比，N-CDs@ZnO复合材料对MB的降解表现出显著更高的光催化活性（60分钟内降解效率超过99%）。此外，降解遵循准一级动力学模型，光催化速率常数（k）为0.0557 min-1，约为裸氧化锌纳米颗粒（0.0240 min-1）的2.3倍。N-CDs在增强N-CDs@ZnO复合材料光催化活性中起关键作用，原因是N-CDs可以有效吸收紫外光并捕获电子，从而阻碍光生电子-空穴对的复合，还抑制了N-CDs@ZnO复合材料中氧化锌纳米颗粒的光腐蚀。N-CDs@ZnO复合材料不仅表现出良好的光催化活性，而且具有良好的稳定性，因为在三次循环测试后光催化活性没有显著降低。本研究表明，N-CDs@ZnO复合材料可被视为染料降解领域的理想光催化剂。总体而言，本方法遵循绿色化学原则，N-CDs@ZnO复合材料的构建简单，该复合材料有望用于开发高效光催化系统。
