The increase in the maximum firing temperature to 450 °C favoured the ART: anatase fraction in unmodified TiO2 was 70.8 wt%, whilst rutile accounted for 19.5 wt%, brookite 9.7 wt%. Yet, copper oxide(s) and graphene modifications delayed the ART. Anatase fraction increased to 89.6 wt% (rutile being 8.6 wt%), and 89.0 wt% (with a rutile fraction equal to 9.8 wt%) in Cu-G0.5/450, and Cu-G1.0/450, respectively. Anatase and rutile diameters in unmodified TiO2 were 8.7 nm, and 14.4 nm, respectively. Those in Cu-G0.5/450, and Cu-G1.0/450 decreased to around 7 nm and 9 nm for anatase and rutile, respectively . XRPD analyses data are listed in Table of the Supporting Information material. Figure shows the TEM study performed on the sample Cu-G1.0/250. The STEM-ADF micrograph (Figure ) shows the superposition of the graphene flake and nanoparticles in the same area. The size of the flakes is typically between 500 and 1000 nm. The corresponding EELS analysis is shown in Figure . The EELs spectra acquired on the graphene flake shows only the presence of the C-K edge, and no edges related to O, Ca and N could be observed in the same spectral range. In addition, the C-K edge present characteristic fine structures of carbon materials with a high sp 2 content . As expected, the EELS spectra acquired on the nanoparticle supported by the graphene flake show the presence of the Ti-L2,3 and O-K edges in addition of the C-K edges. Figure shows a HR-TEM micrograph acquired on the graphene flake, displaying the high crystalline quality of the flake. Automatic indexation of the corresponding FFT (inset of Figure ) shows that this belongs to the graphitic basal plane seen along the [001] zone axis. Figure displays a HR-TEM micrograph acquired on TiO2 nanoparticles. The nanoparticles have a sub-spherical morphology with diameter typically between 5 and 10 nm. Optical spectra of K7000 and those of unmodified TiO2 are shown in Figure . They show a single absorption band at around 3.2 eV, which is assigned to the band-to-band transition in TiO2 . Addition of graphene and copper oxide(s) gave titania further optical features, as displayed in Figure . As also previously shown in , the strong band centred at approximately 1.5 eV is assigned to d-d electronic transitions in Cu 2+ ;