Fig. 2c shows the TEM image of Au@Ag@C, which exhibited a spherical nanoparticle with diameter of about 43 nm. Fig. 2d and e, respectively, exhibit the EDS of the regions D and E on the spherical nanoparticle in Fig. 2c. From Fig. 2d, the weight percentage of C, Ag and Au were 16.74, 17.13 and 66.13%, respectively, and the weight percentage of C, Ag and Au were 0.62, 1.33 and 98.05%, respectively, from Fig. 2e. That is to say, the content of silver at edges (region D) of the nanoparticle was more than the region near center (region E). As shown from the HRTEM image in the inset of Fig. 2c, the outermost layer was the amorphous carbon. In combination with the EDS analysis of each region, we can conclude that (S)-WAY 100135 the second layer was Ag and the core was Au. The thickness of C and Ag layer was 1.67 and 2.3 nm, respectively. According to the above TEM and EDS results, we can conclude the formation of core-double shell Au@Ag@C nanocomposites.
Fig. 3 displays the XRD patterns of CDs, Au@C and Au@Ag@C. The XRD pattern of the CDs shows a secondary (lateral) meristems broad peak at around 20°, which indicates the presence of a non-crystalline material and amorphous nature. The same XRD peak position (around 20°) have been observed for CDs in literatures  and . As to the Au@C, we can observe four diffraction peaks at 38.34, 44.52, 64.88 and 77.8° separately, which correspond to (1 1 1), (2 0 0), (2 2 0) and (3 1 1) lattice planes of Au . The XRD results of the Au@Ag@C was same as the Au@C due to the same structure (face-centered cubic, fcc) and lattice constant of Au and Ag monometallic phase. The XRD results further demonstrate the formation of core-double shell Au@Ag@C nanocomposites.