Scurti Stefano, Monti Eleonora, Rodríguez-Aguado Elena, Caretti Daniele, Cecilia Juan Antonio, Dimitratos Nikolaos
Industrial Chemistry "Toso Montanari" Department, University of Bologna, Viale Risorgimento 4, 40126 Bologna, Italy.
Departamento de Química Inorgánica, Cristalografía y Mineralogía (Unidad Asociada al ICP-CSIC), Facultad de Ciencias, Universidad de Málaga, Campus de Teatinos, 29071 Málaga, Spain.
Nanomaterials (Basel). 2021 Mar 30;11(4):879. doi: 10.3390/nano11040879.
The effect of polyvinyl alcohol (PVA) stabilizers and gold nanoparticles supported on active carbon (AuNPs/AC) was investigated in this article. Polymers with different molecular weights and hydrolysis degrees have been synthesized and used, like the stabilizing agent of Au nano-catalysts obtained by the sol-immobilization method. The reduction of 4-nitrophenol with NaBH has been used as a model reaction to investigate the catalytic activity of synthesized Au/AC catalysts. In addition, we report several characterization techniques such as ultraviolet-visible spectroscopy (UV-Vis), dynamic light scattering (DLS), X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) in order to correlate the properties of the polymer with the metal nanoparticle size and the catalytic activity. A volcano plot was observed linking the catalytic performance with hydrolysis degree and the maximum of the curve was identified at a value of 60%. The Au:PVA-60 weight ratio was changed in order to explain how the amount of the polymer can influence catalytic properties. The effect of nitroaromatic ring substituents on the catalytic mechanism was examined by the Hammett theory. Moreover, the reusability of the catalyst was investigated, with little to no decrease in activity observed over five catalytic cycles. Morphological and kinetic studies reported in this paper reveal the effect of the PVA polymeric stabilizer properties on the size and catalytic activity of supported gold nanoparticles.
本文研究了聚乙烯醇（PVA）稳定剂和负载在活性炭上的金纳米颗粒（AuNPs/AC）的效果。合成并使用了具有不同分子量和水解度的聚合物，作为通过溶胶固定法获得的金纳米催化剂的稳定剂。用NaBH还原4-硝基苯酚作为模型反应，以研究合成的Au/AC催化剂的催化活性。此外，我们报告了几种表征技术，如紫外可见光谱（UV-Vis）、动态光散射（DLS）、X射线衍射（XRD）、透射电子显微镜（TEM）和X射线光电子能谱（XPS），以便将聚合物的性质与金属纳米颗粒尺寸和催化活性相关联。观察到一个火山图，将催化性能与水解度联系起来，曲线的最大值在60%处确定。改变Au:PVA-60的重量比，以解释聚合物的量如何影响催化性能。通过哈米特理论研究了硝基芳环取代基对催化机理的影响。此外，还研究了催化剂的可重复使用性，在五个催化循环中观察到活性几乎没有下降。本文报道的形态学和动力学研究揭示了PVA聚合物稳定剂性质对负载型金纳米颗粒尺寸和催化活性的影响。
