How to access the data: Data in Figure 2: The folder named as ˇ°Matlab fitting codeˇ± is a kind of Matlab code which can be used for fitting the absorption spectrum to obtain diameter distribution. So, Matlab software is required to be installed in a computer/laptop to run the code. Data in Figure 4: (d).003 and (e).003 are atomic force microscope (AFM) images. Gwyddion, a software to process AFM images, is required to be installed in a computer/laptop to open the two files. Data in Figure 5: (a).dm3, (b).dm3 and (c).dm3 are transmission electron microscope (TEM) images. Gatan DigitalMicrograph, a software to process TEM images, is required to be installed in a computer/laptop to open the three files.