The Use of a Biopolymer Conjugate for an Eco-Friendly One-Pot Synthesis of Palladium-Platinum Alloys.

Daniele Silvestri,Rohith K Ramakrishnan,Miroslav Černík,Kamil Krawczyk,Bartłomiej Sobel,Stanisław Wacławek,Vinod V T Padil,Abhilash Venkateshaiah

doi:10.3390/polym11121948

Abstract

Raising health and environmental concerns over the nanoparticles synthesized from hazardous chemicals have urged researchers to focus on safer, environmentally friendlier and cheaper alternatives as well as prompted the development of green synthesis. Apart from many advantages, green synthesis is often not selective enough (among other issues) to create shape-specific nanoparticle structures. Herein, we have used a biopolymer conjugate and Pd and Pt precursors to prepare sustainable bimetallic nanoparticles with various morphology types. The nanoparticles were synthesized by a novel green approach using a bio-conjugate of chitosan and polyhydroxybutyrate (Cs-PHB). The bio-conjugate plays the simultaneous roles of a reducing and a capping agent, which was confirmed by attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) and energy dispersive X-ray spectrometry (EDS) analysis, proving the presence of a Cs-PHB layer on the surface of the prepared nanoparticles. The EDS profile also revealed the elemental structure of these nanoparticles and confirmed the formation of a Pd/Pt alloy. TEM morphological analysis showed the formation of star-like, octahedron or decahedron Pd/Pt nanoparticles, depending on the synthesis conditions. The bimetallic Pd/Pt nanoparticles synthesized with various Pd/Pt molar ratios were successfully applied for the catalytic reduction of 4-nitrophenol to 4-aminophenol by borohydride. The calculated κc values (ratio of kapp to the concentration of the catalyst) revealed that the decahedron nanoparticles (size of 15 ± 4 nm), synthesized at the molar ratio of 2:1 (Pd/Pt), temperature of 130 °C, 10 g/L of Cs-PHB conjugate and time of 30 min, exhibited excellent catalytic activity compared to other bimetallic nanoparticles reported in the literature.

Highlights

The raising health and environmental concerns over nanoparticles synthesized from hazardous chemicals, which are often economically unfeasible, have urged researchers to focus on safer, environmentally-friendlier and cheaper alternatives
We propose a one-pot, quick and green synthesis of decahedral Pd/Pt using solely Pd and Pt precursors and a chitosan and polyhydroxybutyrate (Cs-PHB) bio-conjugate as a reducing reagent
Pd/Pt nanoparticles were synthesized under different conditions

Summary

Introduction

The raising health and environmental concerns over nanoparticles synthesized from hazardous chemicals, which are often economically unfeasible, have urged researchers to focus on safer, environmentally-friendlier and cheaper alternatives. These reasons have prompted the development of green nanoparticle syntheses, which are safe and adhere to the green chemistry approach [1]. Biopolymers, which are abundantly available and biodegradable, are promising materials for providing an environmentally-benign synthesis of nanomaterials. A typical example of a simple monometallic and bimetallic nanoparticle synthesis is the one-step reduction and stabilization of Au and Ag nanoparticles [9,10]

Methods

Results

Conclusion