Effect of Adding Polyethylene Glycol to the Precursor Solution of Amorphous IrO2-Ta2O5 Electrocatalysts for Oxygen Evolution Reaction

We report amorphous iridium oxide (IrO2) and tantalum oxide (Ta2O5) electrocatalysts supported on titanium fiber felt as effective anodes for oxygen evolution reaction (OER). The IrO2-Ta2O5 electrode, prepared by thermal decomposition of the precursor added with polyethylene glycol (PEG), achieved a current density of 10 mA cm−2 at a low overpotential of 0.24 V in a sulfuric acidic solution. The high OER activity is because PEG generated mesopores in the amorphous IrO2-Ta2O5 layer after heating at 350 °C. The increase in the double-layer capacitance, proportional to the electrochemically active surface area (ECSA), was responsible for the high current density at low overpotentials. Furthermore, the addition of the polymer to the precursor suppressed the dissolution of Ir from the anode during the OER stability test and improved the durability of the IrO2-Ta2O5 electrocatalyst coated on the Ti felt