Characterization of photoelectrochemical cells for water splitting by electrochemical impedance spectroscopy

The photocurrent-voltage characteristic of a photoelectrochemical cell for solar hydrogen production via water splitting, using undoped-hematite as photoanode, was obtained. Photoelectrochemical characteristics of the cell were also investigated by electrochemical impedance spectroscopy. Both techniques were carried out in the dark and under illumination. The analysis of the frequency spectra for the real and imaginary parts of the complex impedance allowed obtaining equivalent electrical analogs for the PEC cell operating in the dark and under 1 sun simulated illumination. Additionally, different electrode configurations were used (two and three-electrode arrangements). The two-electrode configuration allowed the study of the overall charge transfer phenomena occurring at the semiconductor, within the electrolyte and at the counter-electrode side of the cell, whereas the three-electrode configuration gave more detailed information concerning the double charged layer at the semiconductor/electrolyte interface.