Nonetheless, the high driving forces for both half reactions as well as the pronounced charge trapping observed for CTF-02 boosts its photocatalytic activity. Overall, the properties of the interface between catalyst and reaction media (wettability, degree of pore filling, Figure ) as well as charge generation improve in the series from CTF-02 and CTF-02-Bpy, while the apparent surface area (Table ) and the band-gap (Figure ) evolve for the worse. These contrasting trends explain why they result in an optimum performance for CTF-02-Bpy 0.66 . This optimum material composition for HER is connected, albeit not exclusively, to the materials' highest hydrophilicity in the series (Figure ); the levelling off of the electron doping towards the triazine moiety at this material composition is a further indicator for its optimal composition.