Controllable Synthesis of Bimetallic Nanostructures Using Biogenic Reagents: A Green Perspective

Abstract

Bimetallic nanostructures are emerging as a significant class of metal nanomaterials due to their exceptional properties that are useful in various areas of science and technology. When used for catalysis and sensing applications, bimetallic nanostructures have been noted to exhibit better performance relative to their monometallic counterparts owing to synergistic effects. Furthermore, their dual metal composition and configuration can be modulated to achieve optimal activity for the desired functions. However, as with other nanostructured metals, bimetallic nanostructures are usually prepared through wet chemical routes that involve the use of harsh reducing agents and hazardous stabilizing agents. In response to intensifying concerns over the toxicity of chemicals used in nanomaterial synthesis, the scientific community has increasingly turned its attention toward environmentally and biologically compatible reagents that can enable green and sustainable nanofabrication processes. This article aims to provide an evaluation of the green synthetic methods of constructing bimetallic nanostructures, with emphasis on the use of biogenic resources (e.g., plant extracts, DNA, proteins) as safe and practical reagents. Special attention is devoted to biogenic synthetic protocols that demonstrate controllable nanoscale features, such as size, composition, morphology, and configuration. The potential use of these biogenically prepared bimetallic nanostructures as catalysts and sensors is also discussed. It is hoped that this article will serve as a valuable reference on bimetallic nanostructures and will help fuel new ideas for the development of more eco-friendly strategies for the controllable synthesis of various types of nanostructured bimetallic systems.

State of the Art on Green Route Synthesis of Gold/Silver Bimetallic Nanoparticles

“…Recently, the main principles of green synthesis have been introduced into the methods of generation of BMNPs. Specifically, the biocompatibility of the substances used to produce the nanomaterials has been considered and thoroughly reviewed [ 22 , 23 ]. A series of the most representative examples of preparations of BMNPs, including biogenetic synthesis and the protocols based on the use of macrocycles, carbohydrate polymers, proteins, and so forth, are summarized in Table 1 and herein discussed.…”

Hyperbranched Au Nanocorals for SERS Detection of Dye Pollutants

“…This has prompted the use of biogenic resources as environmentally benign and costeffective substitutes to the harsh and expensive reagents that are often employed in previously established synthetic procedures. 7,8 One of the most promising biogenic methods in the preparation of Au nanostructures is phytosynthesis, which engages the use of plant extracts from different plant parts (e.g., fruits, leaves, flowers). 9−11 The extracts derived from plants are basically a concoction of phytochemicals that can serve significant roles in nanostructure formation.…”

“…In recent years, considerable attention has been devoted to finding greener and cheaper reagents for metal nanomaterial synthesis to reduce cost and avoid damaging effects to human health and the environment. This has prompted the use of biogenic resources as environmentally benign and cost-effective substitutes to the harsh and expensive reagents that are often employed in previously established synthetic procedures. , One of the most promising biogenic methods in the preparation of Au nanostructures is phytosynthesis, which engages the use of plant extracts from different plant parts (e.g., fruits, leaves, flowers). − The extracts derived from plants are basically a concoction of phytochemicals that can serve significant roles in nanostructure formation. However, the exact mechanism for the phytochemical-mediated formation of Au nanostructures is not yet fully established.…”

Green synthesis of biocompatible core–shell (Au–Ag) and hybrid (Au–ZnO and Ag–ZnO) bimetallic nanoparticles and evaluation of their potential antibacterial, antidiabetic, antiglycation and anticancer activities

“… 1 The synthesis of BNPs via a green route is gaining particular attention as NPs are produced without any harsh synthesis conditions or using expensive and hazardous chemicals. 2 Moreover, plant mediated synthesis of BNPs has an advantage of producing biocompatible BNPs as they are capped by therapeutically important plant secondary metabolites. 3 Among different types of BNPs, gold (Au) is the most biologically prepared bimetallic nanostructure reported so far.…”