In this study, electrons must be transported from the FTO glass to the first layer of TiO2 nanoparticles, where they can reach the precursors ([PtCl4]2−). In other words, the electrochemically deposition of Pt NPs takes place preferentially at theTiO2/FTO interface. Afterwards, TiO2 semiconductor may favor thedeposition of Pt on already deposited Pt NPs.