2018 Volume 86 Issue 5 Pages 235-242
The characteristics for 3,4,9,10-perylenetetracarboxylic-bisbenzimidazole (PTCBI, an n-type semiconductor) and 29H,31H-phthalocyanine (H2Pc, a p-type semiconductor) as organic p/n bilayer and bulk heterojunction (BHJ) photoelectrodes were studied for the photooxidation of thiol. Based on the analysis in their absorption spectra, a new absorption band in the longer wavelength (λ > 800 nm) for both bilayer and co-deposited photoelectrode suggested a formation of charge transfer complex. A photoanodic current was observed at λ ∼ 880 nm for the both bilayer and co-deposited electrodes, while no absorption and photocurrent for single layers of PTCBI and H2Pc. By assuming the Langmuir adsorption equilibrium at the solid/water interface, the kinetic parameters for the photoanodic current of thiol was analyzed for the longer wavelength of irradiation (λ ∼ 900 nm), and it was indicated that the rate of oxidation in the co-deposited was higher than that of the bilayer due efficient charge separation in the charge transfer complex.
