It is interesting to focus here briefly on the preponderance of each of these mechanisms. First, it is an accepted fact that Ti doping increases the electrical conductivity acting as n-type doping in the hematite semiconductor, increasing thus the measured photocurrent during the PEC process. Figure presents the comparison between two additional samples, one annealed in air and the other under Nitrogen, containing 30 times less Ti compared to S1 and S2 samples. On one hand, it is important to note that even at this very low Ti content level the photocurrent is increased compared to bare hematite. There is barely any visible difference between the two cases, the sample annealed under Nitrogen exhibiting only slightly higher photocurrents above 1.3 V vs. RHE. It appears thus that for very low Ti contents, the Nitrogen annealing has marginal effects on the recorded photocurrent. We can conclude therefore that the increase expected from additional oxygen vacancies doping, formed upon annealing under Nitrogen, is negligible. Consequently, the photocurrent enhancement we determine for the S1 sample compared to the S2, is mainly due to the formation of surface states promoting enhanced charge separation.