Dependence on electrode potential of the magnetic field effect on photoelectrochemical reactions of electrodes modified with porphyrin-viologen linked compounds

Modified indium tin oxide (ITO) electrodes are prepared by depositing monolayers containing porphyrin-viologen linked compounds with various length spacer chains [ZnP(n)V (n = 4, 6, 8)] and arachidic acid (1 :10) using the Langmuir-Blodgett method. The electrochemical properties of the ZnP(n)V (n = 4, 6, 8)-modified electrodes indicate that the linked compounds [ZnP(n)V (n = 4, 6, 8)] are immobilized on the ITO electrode surface so with the molecules oriented to put the viologen moiety nearest to the electrode. A stable anodic photocurrent is produced by irradiating the modified electrodes with visible light, and the photocurrent Is clearly enhanced by the application of a magnetic field. The influence of the electrode potential upon the magnetic field effects on the photocurrent in the ZnP(8)V-modified electrode is also examined. With increasing electrode potential, the photocurrent increases but the magnetic field effects weaken. The influence of electrode potential on the magnetic field effects is explained by the radical pair mechanism at the ITO electrodes.