Dye Sensitization in a Photoelectrochemical Water-Splitting Cell Using N,N'-Bis(3-phosphonopropyl)-3,4,9,10-perylenedicarboximide

Abstract

Enhanced surface area thin film titania electrodes were prepared by spin coating of a titania sol onto fluorine tin oxide substrates. The electrodes were characterized by profilometry, scanning electron microscopy, and ultraviolet-visible light spectrometry. Capacitance measurements were used to assess surface area enhancement. The propylphosphonic acid derivative of perylene diimide was synthesized for use in sensitization of the titania films. Complete purification of the crude product was complicated due to the low solubility of the dye derivative. Nonetheless, mass spectrometry, gel electrophoresis, nuclear magnetic resonance, infrared spectrometry, and elemental analysis were carried out to characterize the product. Electrochemical measurements were used to study the efficacy of the dye as a titania sensitizer. The results indicate the perylene derivative is energetically capable of water oxidation. However, charge transfer from the dye into the titania layer was not seen. It is believed this is due to an energy band mismatch between the reduction potential of the dye and the conduction band of the titania layer.