A highly robust and reusable polyimide-supported nanosilver catalyst for the reduction of 4-nitrophenol
- PDF / 542,225 Bytes
- 9 Pages / 584.957 x 782.986 pts Page_size
- 33 Downloads / 170 Views
A simple and efficient method for in situ preparation of highly stable polyimide (PI)-supported silver nanoparticles (AgNPs) was proposed. This process achieves excellent dispersion and high stability of AgNPs in the PI matrix. The formation of AgNPs in PI and the morphology evolution of PI/Ag nanocomposites were characterized by x-ray diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy (FT-IR), and x-ray photoelectron spectra studies. The catalytic properties of these PI-supported AgNPs were investigated by monitoring the reduction of 4-nitrophenol by excess NaBH4 in water. The catalytic reaction was observed to have a pseudo first-order rate constant of 0.567 min1 (9.45 103 s1), which is comparable to other heterogeneous silver catalysts reported in the literature. Notably, the PI-supported AgNPs retained their relatively high catalytic activity over seven recycles with almost no leaching of catalytic species in the reaction solution. Moreover, the catalytic activity of the catalyst is still quite appreciable even after a six-month shelf-storage under room temperature.
I. INTRODUCTION
Recently, metal nanoparticles have attracted intensive attention in various areas, such as catalysis, optics, electromagnetics or plasmonics, antibacterials, etc.1–6 The interest in these nanoparticles stems from their unique characteristics as compared to their bulk counterparts. For example, it has been both experimentally and industrially demonstrated that noble metallic nanoparticles perform better in catalysis because of their high chemical activity and specificity of interaction.1,2 Among them, silver is the most attractive in terms of its much lower cost, and silver nanoparticles (AgNPs) are well known to be efficient catalysts for the selective oxidation of olefins and the reduction of many organic dyes and nitroaromatic compounds.2,7–10 However, in most cases, the performance of the AgNPs degrades over time as a result of agglomeration and leaking during the fabrication and application processes. In this regard, AgNPs have often been immobilized onto various supports, including inorganic, organic, and polymeric materials.7,11–14 Since Merrifield15 first reported the concept of solidphase peptide synthesis with heterogeneous chloromethylated polystyrene half a century ago, many soluble or insoluble polymers have been widely implemented in organic synthesis and product isolation.16–18 Although soluble polymer- or dendrimer-aided catalysis has received
Contributing Editor: Xiaobo Chen a) Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/jmr.2015.258 J. Mater. Res., Vol. 30, No. 18, Sep 28, 2015
http://journals.cambridge.org
Downloaded: 02 Sep 2016
more attention in the academic community due to its huge activity, which is almost comparable to homogeneous catalysis, the relatively low rates of recovery and reuse of these labile catalysts are still urgent issues from an industrial perspective.19–21 In contrast, the use of functional resins (i.e., insoluble poly
Data Loading...
