WATER SPLITTING STUDIES IN ALKALINE MEDIUM USING GRAPHITE ELECTRODES MODIFIED WITH TRANSITION METAL OXIDES AND COMPOSITIONS CONTAINING THEM.

Present day scientific research is focused on the identification of renewable and clean alternatives to fossil fuels, with hydrogen being a promising energy source that fulfills both requirements. Given this context, the current work investigates the water splitting electrocatalytic properties of two hydrothermally synthesized transition metal oxides: MnO2 and Fe3O4. Electrodes were obtained by modifying graphite substrates with suspensions in ethanol containing the catalytic materials as such or in compositions, and their activity for the O2 and H2 evolution reactions (OER and HER) was studied in alkaline medium. Out of the MnO2-based electrodes, the one modified with the suspension containing 2 mg MnO2, 1 mg Carbon Black and 10 μL Nafion solution displayed an OER overpotential (ηO2) value, at i = 10 mA/cm2, of 0.53 V, while the one manufactured using the suspension with 4 mg MnO2 and 10 μL Nafion solution showed a HER overpotential (ηH2) of 0.427 V (at i = -10 mA/cm2). From the Fe3O4-based electrodes, the one modified with the suspension containing 2 mg Fe3O4 and 2 mg Carbon Black evidenced the highest catalytic activity for both reactions (ηO2 = 0.51 V and ηH2 = 0.43 V). [ABSTRACT FROM AUTHOR]