The correlation of photocatalytic rate constant (k) with various electrochemical parameters was attempted previously by various authors, but it was generally limited to TiO2 systems. For instance, Baram et al. (2010) studied mesoporous TiO2 for photocatalytic degradation of methylene blue using EIS. They showed from the Mott-Schottky analysis and polarization curves, that a high surface area of tubular TiO2 does not translate into good photocatalytic activity. A similar result we have also reported in our previous study for ZnO sheets and Rhodamine dye. Likewise, Baumanis et al. ( ) studied TiO2 thin film electrodes using Mott-Schottky measurements for photocatalytic reduction and oxidation of methyl viologen and methylene blue respectively. They reported a correlation of photocatalytic activity with flat donor density and flat band potential. However, in this study, we investigated the interfacial charge transfer dynamics of the morphologically distinct iron oxide (hematite) and rhodamine dye, by examining the multiple electrochemical parameters. The surface redox potentials (E ₀ ), differential capacitance (Cdl), and charge transfer resistance (Rct) were examined to assess their influence on the system. To further understand interfacial properties, the electrochemically active surface area (ECSA) and electrochemical work function (𝛷 𝑎𝑑 0 ) were also analyzed. Moreover, the potential of zero charge (Epzc) at the catalyst surface was investigated to explore its correlation with the observed photocatalytic rate constants (k). For instance, in the anodic (0.3 to 2.5 vs RHE) scans (Fig. ) of all the interface systems, two redox peaks were observed at ca. 0.45 V and 0.9 V vs RHE, is attributed to Fe + / Fe 2+ and Fe 2+ /Fe 3+ redox species. Interestingly, the peak current (jp,a) to Fe 2+ /Fe 3+ transformation for the FeAH system is higher than the other samples. However, the redox peaks in FeCT (Fig. ) are absent in this potential window, probably due to surface modification. Besides that, the reduction peak corresponding to Fe 3+ / Fe 2+ is much more dominant in the FeAH sample (Fig. ). This showed the clear electronic and surface modification of the catalyst systems due to synthetic conditions altering the energy barrier for the redox processes at the interface. The highest peak current in the FeAH system (Fe2O3) correlates with its highest (k). Likewise, a similar correlation is observed in other cases (Fe2O3) also, excluding the FeBH due to its structural (Fe3O4) variation in the form.