Mota Danielle Ramos, Martini William da Silva, Pellosi Diogo Silva
Laboratory of Hybrid Materials, Department of Chemistry, Federal University of São Paulo, Rua São Nicolau 210, Diadema, SP, 09913-030, Brazil.
Environ Sci Pollut Res Int. 2023 Apr;30(20):57667-57682. doi: 10.1007/s11356-023-26580-7. Epub 2023 Mar 27.
In this work, we propose zinc oxide (ZnO) surface functionalization with plasmonic silver nanoparticles (AgNP) of different sizes and shapes (spheres, prisms, and rods) creating ZnO/AgNP nanohybrids. These were characterized by UV-Vis spectroscopy, X-ray diffraction, transmission electron microscopy, Fourier-transform infrared spectroscopy, diffuse reflectance spectroscopy, and photoluminescence spectroscopy. Surface functionalization with AgNP improved photocatalyst electronic properties, its visible light absorption, and slow electron/hole recombination on the ZnO surface. Photocatalysis assays performed with a polychromatic Hg lamp degraded methyl orange, a model of persistent organic pollutant in water. A systematic study showed that the photodegradation kinetics of the nanohybrids are significantly more efficient than pure ZnO (up to 18 times) and that AgNP size and especially its shape are important in dye degradation. Mechanistic studies revealed that degradation occurred by direct dye reduction on the ZnO surface holes, ZnO electron transfer to Ag followed by •O formation, and direct injection of AgNP hot electrons in the ZnO conduction band. The last effect was stronger for anisotropic AgNP, which explains their high kinetic degradation rates. Therefore, the rational design in ZnO/AgNP nanohybrid engineering and a systematic approach used in this manuscript allowed a detailed description of photodegradation process that occur at ZnO/AgNP interface. Our results are not conclusive about AgNP size; on the other hand, it clearly demonstrates that anisotropic nanoparticles (as Ag rods and prims) present superior photodegradation efficiency and are promising particles for further large-scale use of solar-irradiated nanohybrids.
在本研究中，我们提出用不同尺寸和形状（球形、棱形和棒形）的等离子体银纳米颗粒（AgNP）对氧化锌（ZnO）进行表面功能化，制备ZnO/AgNP纳米杂化物。通过紫外-可见光谱、X射线衍射、透射电子显微镜、傅里叶变换红外光谱、漫反射光谱和光致发光光谱对其进行了表征。用AgNP进行表面功能化改善了光催化剂的电子性质、其可见光吸收以及ZnO表面电子/空穴的缓慢复合。用多色汞灯进行的光催化实验降解了甲基橙，甲基橙是水中持久性有机污染物的模型。一项系统研究表明，纳米杂化物的光降解动力学比纯ZnO显著更高效（高达18倍），并且AgNP的尺寸尤其是其形状在染料降解中很重要。机理研究表明，降解是通过ZnO表面空穴上的直接染料还原、ZnO电子转移到Ag随后形成•O以及AgNP热电子直接注入ZnO导带而发生的。对于各向异性的AgNP，最后一种效应更强，这解释了它们较高的动力学降解速率。因此，ZnO/AgNP纳米杂化物工程中的合理设计以及本手稿中使用的系统方法允许详细描述在ZnO/AgNP界面发生的光降解过程。我们的结果关于AgNP尺寸尚无定论；另一方面，它清楚地表明各向异性纳米颗粒（如Ag棒和棱形）具有优异的光降解效率，并且是用于太阳能辐照纳米杂化物进一步大规模应用的有前景的颗粒。
