Molecularly doped polythiophene film as an efficient photocathode for oxygen reduction to hydrogen peroxide

The molecularly doped poly(3-hexylthiophene) (P3HT) was used for the first time as a photocathode for reducing oxygen to H₂O₂. For this purpose, a P3HT film was doped with hexaazatriphenylenehexacarbonitrile, which increased the oxygen reduction current at an applied negative potential in the dark. Visible light illumination of the doped P3HT film significantly facilitated the oxygen reduction with a high current density and shifted the onset potential beyond the reaction equilibrium potential. The oxygen reduction performance of the doped P3HT film is discussed in relation to the energy level diagram.