Photocatalysis of the oxygen reduction reaction at adsorbate-covered silver

The oxygen reduction reaction, the slow kinetics of which is well-known to limit efficient energy production from fuel cells, is shown to be catalyzed at adsorbate-covered silver electrodes when the electrode is irradiated with wavelengths in the visible and near-ultraviolet. 'We report the photocurrent dependence on adsorbate molecule, electrode voltage, excitation wavelength, and oxygen content of the solution. Comparison of the photocurrent excitation profile with the modulated electroreflectance spectrum identifies coupling of two resonances to the catalysis; the silver surface plasmon near 400 nm and another resonance near 550 nm assigned to metal-to-adsorbate charge transfer.