Effectiveness factor of fast (Fe3+/Fe2+), moderate (Cl2/Cl−) and slow (O2/H2O) redox couples using IrO2-based electrodes of different loading
- First Online:
- Cite this article as:
- Calderon, E.H., Katsaounis, A., Wüthrich, R. et al. J Appl Electrochem (2009) 39: 1827. doi:10.1007/s10800-009-9886-2
The effectiveness factor, Ef, (fraction of the electrode surface that participates effectively in the investigated reaction) of fast (Fe3+/Fe2+), moderate (Cl2/Cl−) and slow (O2/H2O) redox couples has been estimated using IrO2-based electrodes with different loading. The method of choice was linear sweep voltammetry (measurement of the anodic peak current) for the Fe3+/Fe2+ redox couple and steady-state polarization (determination of the exchange current) for the O2 and Cl2 evolution reactions. The results have shown that the effectiveness factor depends strongly on the kinetics of the investigated redox reaction. For the Fe3+/Fe2+ redox couple, effectiveness factors close to zero (max 4%) have been obtained contrary to the O2 evolution reaction where effectiveness factors close to 100% can be achieved, all being independent of IrO2 loading. For the Cl2 evolution reaction, intermediate values of the effectiveness factor have been found and they decrease strongly, from 100% down to about 60%, with increasing loading.