The formation of single layers of FGO and the deposition of Ag- NPs on its surface was confirmed by the FESEM and TEM studies. The FESEM (Fig. 3A) and TEM (Fig. S2) images indicate the forma- tion of single layer FGO with size greater than 1 lm. Fig. 3 displays FESEM images of the FGO/Ag nanocomposites at different pHs. Even though the concentrations of silver nitrate and FGO were kept constant in all samples, the Ag-NPs show different morphologies with the variation in the pH, suggesting an effect of pH on forma- tion of the Ag-NPs. The average size of the NPs calculated from the FESEM and TEM images are in good agreement with each other and are presented in Table 1. The sizes of the Ag-NPs decreased from
83±53 to 24±7nm with an increase in pH from 9.51 to 11.40, and at higher pH the particle size increased again (see Table 1). The standard deviation in the particle size distribution also fol- lowed a similar trend. Thus, a narrow particle size distribution was observed at pH 11.40 and increased with the variations in the pH of the solution. The TEM and FESEM images also support the formation of silver particles with irregular shapes and a wide size distribution at pH’s 9.51, 10.38 and 12.62. In contrast to this, spherical and narrowly distributed NPs were obtained at pH 11.40 (see Fig. 3C). This can be explained based on the reducing power of the silver ions at different pHs. At a lower pH, the reduc- tion of silver ions is slow and incomplete; hence particle growth is also slow and random. Whereas at higher pH (12.62), the presence of excessive OH