A Review on Multifunctional Silver Nanoparticles Produced With Green Routes for Photocatalysis, Sensing, and Imaging

Introduction

Metallic nanoparticles (NPs) have found usage in various fields by showing improved physicochemical and biological properties as a modified nano-engineering materials at the nano-scale compared to their macro-scale structures (Das & Ansari, 2009; Iliger et al., 2021; Yongfei Wang et al., 2019). Metallic NPs recently come to the fore in nanotechnology applications due to reasons such as having less toxicity at the nanoscale compared to the atomic level, free electrons in the conduction bands improve the optical properties of metallic NPs and thus surface plasmon resonance (SPR) can be observed in the UV-Visible regions, allowing photothermal treatment due to their ability to convert light/radio frequencies into heat (Vaid et al., 2020). NPs synthesis methods were classified as bottom-up and top-down synthesis. In this classification, the methods were classified according to their initial size. While the methods that perform synthesis from atomic size to nano size are divided as bottom-up, methods that perform synthesis by reduction from bulk/macro size to nano size are divided as top-down. Another classification of methods is physical, chemical, and biological (Chavali & Nikolova, 2019; Jamkhande et al., 2019; Nasrollahzadeh et al., 2021; Rana et al., 2020; Vaid et al., 2020). A general classification of methods was shown in Figure 1.

Figure 1.

Classification of the NPs synthesis methods