All filenames contain indication of the figure they refer to. 

Figure 1: all XRD files report the setup of the diffractometer, the 2theta angle in the first column, the XRD intensity in the second column. 
Figure 3: the foled %R contains the raw data of the diffuse reflectance measuremetns used to calculare the absorbance of the samples. 
Figure 4: the folder TG contains the raw data the 4 columns are lacelled: temperature, time, differential thermal analysis, and mass %. 
Figure 5: the folder PEC-(Fig5). The 4 columns are: applied potential vs. Al/AlCl reference electrode, current sample-SS, (Nb)-PC, and -PC. 
Figure 7: the folder PEC-(Fig7). The 4 columns are: applied potential vs. Al/AlCl reference electrode, current sample-SS, (Nb)-PC, and -PC. 
Figure 8a: the folder PEC-(Fig8). The 4 columns are: applied potential vs. Al/AlCl reference electrode, current sample-SS, (Nb)-PC, and -PC. 
Figure 8b: the folder XPS contains the raw data of teh XPS analysis before baseline correction and normalization. Columns 1 and 2 arre binding energy (eV) and XPS intensity (counts/s) for sample (Nb)-PC-copi, columns 3 and 4 are binding energy (eV) and XPS intensity (counts/s) for sample (Nb)-PC Al2O3