Figure 2 displays the TEM images of colloidal
AgNP and evidences a high degree of agglomeration.
However, the agglomerates consist of small silver
particles (Figire 2b). The PSD obtained by DLS
indicates an average diameter of 20 nm. Bearing in
mind that PSD and UV–Vis of the colloidal dispersion
point to spherical AgNP with 20-nm diameter, aggregation
probably occurred during drying onto the
copper grid. This happened because the AgNP were
not capped with any passivation molecule during the
synthesis.