Electrochemical Reaction of Aqueous Iron Sulfate Solutions Studied by Fe L‑Edge Soft X‑ray Absorption Spectroscopy

Change in valence of Fe ions in aqueous iron sulfate solutions at different potentials has been studied by Fe L-edge soft X-ray absorption spectroscopy (XAS) in transmission mode. Each XAS spectrum is measured at a constant potential by using a liquid cell with built-in electrodes. A nonlinear oxidation of Fe(II) ions to Fe(III) ions is observed when the potential is increased from 0.0 to 0.9 V. Two processes are found in the oxidation: one is …