Role of Pt and PtO 2 in the Oxygen-Evolution Reaction in the Presence of Iron under Alkaline Conditions.

The oxygen-evolution reaction (OER) through water oxidation is an inevitable reaction for water splitting toward storing energy. However, OER is a four-electron and slow reaction, which is also a bottleneck for water splitting. To find the role of Pt and PtO 2 on the OER in the presence of Fe, the electrochemistry of Pt foil and PtO 2 is investigated in the absence/presence of K 2 FeO 4 as a soluble Fe salt at pH ≈ 13. After the addition of K 2 FeO 4 , a remarkable increase in the OER is recorded in the presence of Pt or PtO 2 . The obtained catalysts were characterized by operando visible spectroscopy, high-resolution transmission electron microscopy, scanning electron microscopy, electron-spin resonance spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and electrochemical methods. KOH solutions usually contain Fe and/or Ni impurities. It is found that neither Pt nor PtO 2 is an OER catalyst in a Ni/Fe-free KOH, and even at an overpotential of 570 mV in purified KOH (pH ≈ 13), no clear OER was observed.