Solid-State Green Synthesis of Ag NPs: Higher Temperature Harvests Larger Ag NPs but Smaller Size Has Better Catalytic Reduction Reaction

Dina Sadeq Al-Namil,Digambara Patra,Elsy El Khoury

doi:10.1038/s41598-019-51693-w

Abstract

In this work a novel solid-state green approach without using any solvent environment has been proposed to synthesize Ag NPs. The synthetic condition has been investigated in 4 °C, 20 °C, 40 °C and 60 °C and at ten different time intervals. This synthesis process gives different size and shape of curcumin conjugated Ag NPs, which have been confirmed by various morphological and spectroscopic techniques. It is found that higher temperature and longer time produces larger particles size and different varieties in shapes. For example, Ag NPs prepared at 4 °C are spherical shapes whereas that prepared at 60 °C are of spherical, rods, and many hexagonal shapes. At 60 °C and after 5 and 7 days the size of the prepared Ag NPs exceed the nano scale to reach micro scale level. This size and shape distribution are well reflected in the optical properties as absorbance, fluorescence intensity and SFS intensity of Ag NPs consistently increase with increase in temperature during synthesis. Ag NPs obtained in different temperature and various time intervals have been subsequently tested as catalysts for the reduction reaction, where 4-nitrophenol is reduced to 4-aminophenol in the presence of NaBH4. It is found that smaller particles have better catalytic properties for the reduction reaction.

Highlights

Synthesis of silver nanoparticles is an area that has witnessed much enthusiasm in recent time[13]
Ag NPs synthesized in four different temperatures 4 °C, 20 °C, 40 °C and 60 °C and at ten different time intervals provided different size and shape of curcumin conjugated Ag NPs, as confirmed by various morphological and spectroscopic techniques
Ag NPs prepared at 4 °C were spherical shapes and that prepared at 60 °C were of spherical, rods, and many hexagonal shapes

Summary

Introduction

Synthesis of silver nanoparticles is an area that has witnessed much enthusiasm in recent time[13]. These Ag nanoparticles have exceptional optical, electrical, chemical and magnetic properties which are not same as that obtained for their bulk match. The synthesized Ag NPs using the extract of Gloriosa superba is based on the electron relay phenomena which will induce the degradation of methylene blue at the end of the 30 min[17]. In this manuscript, we report for the synthesis of Ag NPs using curcumin via solid state green synthetic approach. The prepared curcumin conjugated Ag NPs have been tested as catalyst for the reduction reaction of p-nitrophenol

Methods

Results

Conclusion