XPS spectra of (GO/rGO)/TNP films recorded in the N 1s core level indicate the removal of the amine group by a decreasing peak intensity with increasing DUV exposure time. However, the rather low signal-to-noise ratio does not enable a quantitative analysis (Supporting Information, Section S8). Spectra of analogous TNR-based films revealed the same trends as shown in Figure for the TNP-based films and are provided in the Supporting Information, Section S8. Additional characterization of the photocatalytic reduction was performed via FTIR spectroscopy. The corresponding data can be found in the Supporting Information, Section S5. Briefly, the measurements are in agreement with the XPS data, demonstrating the formation of rGO. FTIR analysis qualitatively indicates the removal of epoxy and hydroxy groups.