Various metal and semiconductor substrates demonstrated greatly enhanced activity toward the electrolysis of the benzoquinone (Q) hydroquinone (H2Q) redox couple when coated with multimolecular layers of chlorogallium phthalocyanine (GaPc-Cl) and irradiated with visible wavelength light. These electrodes were nearly reversible toward H2Q in the light, but were quite inert in the dark, even suppressing corrosion of the metal when silver substrates were used. Exchange current densities on GaPc-Cl/Au electrodes irradiated with approximately 100 mW/cm2 polychromatic light were ca. 103 times greater than on plain Au. The improved voltammetric response of these electrodes over other Pc film electrodes are attributable in part to the sublimation conditions employed, distinguished primarily by a deposition rate of tens of angstroms per minute or less. Varying degrees of film porosity were obtained as evidenced by cyclic voltammetry and x-ray photoelectron spectroscopy. The role of GaPc-Cl in activating the substrate surface is briefly discussed, contrasting the behavior of GaPc-Cl/Au electrodes to plain Au, which shows two distinct rates of Q/H2Q electrolysis, depending on electrochemical pretreatment.
- molecular metals
- quinone electrolysis
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Renewable Energy, Sustainability and the Environment
- Surfaces, Coatings and Films
- Materials Chemistry