Photocurrent density, 𝐽 𝑝ℎ = 𝐽 𝑂𝑁 -𝐽 𝑂𝐹𝐹 , was measured following two protocols that were described in a previous work. For that purpose, we measured the current density for light ON (𝐽 𝑂𝑁 ) and respective OFF (𝐽 𝑂𝐹𝐹 ), as a function of the applied potential using a three-electrode electrochemical cell, where the photoanode was either the Nitrogen or the air annealed Ti-doped hematite films grown by ACG (S1 and S2, respectively -see sections 4.1 for details about the synthesis). First, voltammetry measurements were performed by varying the voltage between 0.6 and 1.7 V vs. RHE, with a sweep rate of 50 mV/s (Figure ). Second, photocurrent density was measured as a function of time while keeping the applied voltage constant. Current density is read once stabilized for an applied voltage in the interval 0.8 -1.6 V vs. RHE. This protocol allows to measure stabilized photocurrent values as the step height between light OFF and ON values (blue and red dot respectively in Figure ). The photocurrent values obtained using the two types of measurements (represented with solid lines and symbols for the first and the second approaches, respectively) are represented in Figure for both samples, S1 and S2, as a function of the applied potential.