The electronic properties of CTF and Ru-CTF hybrid materials were studied through UV-vis diffuse reflectance spectroscopy (DRS), Mott-Schottky (M-S) analysis (Fig. ) and Photoluminescence (PL) experiments (Fig. ). The Mott-Schottky experiments displayed in Fig. give a value of the Fermi level, EF = -0.80 V (vs. NHE at pH 7) for both CTF and Ru-CTF, calculated at middle frequencies in the range of 0.5 -2 MHz, that can be taken as an approximation for the conduction band energy (Ec) in n-type semiconductors. The Tauc plots shown in Fig. give a band gap energy (Eg) of 2.90 eV again for both CTF and Ru-CTF, which is consistent with the absorbance spectra (Fig. ). The absorption bands below 450 nm are associated with typical π-π* and n-π* electronic transitions of the polypyridyl ligands and the triazine units. The Ru-CTF material shows an additional MLCT band at λmax = 546 nm, indicative of the electronic transition between the Ru metal center and the tda ligand (Fig. ) .