We discuss here for the first time how to combine iron and titanium metal ions to achieve a high photo-electrochemical activity for TiO 2 -based photo-anodes in water splitting devices. To do so, a wide range of photoelectrode materials with tailored Ti/Fe ratio and element vicinity were synthesized by using the versatility of aqueous sol-gel chemistry in combination with a microwave-assisted crystallization process. At low ferric concentrations, single phase TiO 2 anatase doped with various Fe amounts were prepared. Strikingly, at higher ferric concentrations, propose that the nature of the heterojunction impacts charge carrier recombination. The results presented herein not only answer whether iron and titanium should be combined in the same structure or into heterostructured systems, but also on the importance of the arrangement of ions in the structure to improve the performances of the photoanode.