Table 1 Fundamental functions of the analytical techniques used for the characterization of AgNPs

X-ray diffraction

Measure the degree of crystallinity at the atomic scale. Used to analyze the structure of nanoparticles, particle sizes, for compounds identification, and to determine structure imperfections in the structures. The analysis depends on the formation of diffraction patterns (Alheety et al. 2019)

X-ray photoelectron spectroscopy

Determine the electronic states by atoms which include the oxidation state, and electron transfer in the nanoparticles. Estimate the empirical formulae by surface chemical analysis. Characterize the nanoparticles’ surface in the liquid forms (Pourzahedi and Eckelman 2015)

Fourier transform infrared spectroscopy

Characterize various chemical bonding in nanomaterials (Pal et al. 2017)

UV–Vis spectroscopy

Evaluate the stability and characteristics of AgNPs. Absorption of AgNPs depends on the dielectric medium, particle size, and the chemical environment. Size depends on surface plasmon for metal nanoparticles ranging from 2 to 100 nm (Nguyen et al. 2018)

Transmission electron microscopy

Measure of particle size, morphology, and size distribution. Provide better spatial resolution compared to SEM (Baudot et al. 2010)

Scanning electron microscopy

Evaluate the morphology of AgNPs. Histogram obtains from images. Manually measure and count the particles or using specific software (Gorham et al. 2012)

Dynamic light scattering

Measure nanoparticles size. Evaluate their stability over time in suspension at different pH and temperature conditions (Balaji et al. 2009)

Localized surface plasmon resonance

Determine spatial oscillation of non-excited or excited (near-visible light) electron. Evaluate the molecular interaction on the surface of a nanoparticle. Depends on several factors: particle’s size and shape electronic properties, dielectric media, and temperature (Chen et al. 2017)