Hyaluronic Acid-Guided Synthesis of Pd Nanocatalysts for Transfer Hydrogenation of 4-Nitrophenol
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Hyaluronic Acid‑Guided Synthesis of Pd Nanocatalysts for Transfer Hydrogenation of 4‑Nitrophenol Danyang Yin1,2 · Jinli Zhang1,2 · Wei Li1,2 · Yan Fu1,2 Received: 23 July 2020 / Accepted: 4 November 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract Herein Pd nanocatalysts for transfer hydrogenation were synthesized by using hyaluronic acid (HA) as both the reductant and the stabilizer. The effects of molecular weight of HA, molar ratio of [HA]/[Na2PdCl4] and reduction temperature, were evaluated in Pd-catalyzed transfer hydrogenation of 4-nitrophenol. The most active Pd NPs show the TOF value of 131.07 h−1 at 50 °C with the equimolar mixture of formic acid and sodium formate. Further, uniformly distributed Pd NPs were successfully synthesized through the reduction of Pd (II) precursors on HA-modified magnetic NPs, which were constructed through electrostatic layer-by-layer assembly. The hybrid catalysts also exhibit high activity with the mixed hydrogen source. This work paves a promising way to construct highly active hybrid catalysts through the combination of in-situ reduction and electrostatic layer-by-layer methods. Graphic Abstract
Keywords Polysaccharide · Palladium · Nanoparticle · Layer-by-layer · Reduction
1 Introduction
Electronic supplementary material The online version of this article (https://doi.org/10.1007/s10562-020-03455-x) contains supplementary material, which is available to authorized users. * Yan Fu [email protected] 1
School of Chemical Engineering and Technology, Tianjin University, 135 Yaguan Road, Jinnan District, Tianjin 300350, People’s Republic of China
Frontier Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (Ministry of Education), Tianjin University, Tianjin 300072, People’s Republic of China
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Polysaccharides are capable of binding and reducing transition metal ions under mild conditions to generate water-soluble nanoclusters or nanocrystals. Polysaccharides-guided construction of functional metal nanomaterials significantly reduces the harmful by-products to the environment, which meets the concept of green chemistry [1–3]. Up to date, a variety of polysaccharides involving D-(+)-xylose, heparin, hyaluronic acid (HA), β-1,3-D-glucan and so on, have been utilized to reduce the metal precursors and to control the size distribution of Ag and Au nanoparticles (NPs) [4–8]. For example, Yan et al. adopted β-1,3-D-glucan for one-pot synthesis of controllable Au NPs ranging from 5 to 45 nm, which efficiently catalyzed the hydrogenation of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) by excess boron
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hydrogen compounds. Veisi et al. [9] prepared chitosanencapsulated Fe3O4 NPs as magnetic carriers to in situ synthesize ultra-fine spherical Pd NPs (~ 5 nm). The exterior Pd NPs exhibit high activity and stability in the synthesis of biaryl derivatives as well as the reduction of 4-NP. To enhance the applicability of polysaccharide-stabilized metal NPs, it is of vital importance t
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