Photoelectrochemical properties of dye-dispersing allophane–titania composite electrodes

• Dye and allophane-dispersing titania electrodes were prepared by a sol–gel method.
• Photoinduced electron injection efficiency was increased by adding 1.0% allophane.
• The highly dispersed dye molecules strongly interact with the titania surface.
• The dye molecules on the titania surface were capped with allophane nanoparticles.
• The highly dispersed allophane did not decrease the electron injection efficiency.

Dye-dispersing allophane–titania composite electrodes were prepared from titanium alkoxide sols containing dye and allophane. The photoelectric conversion properties of the electrodes were investigated by photoelectrochemical measurements. The photocurrent values in the UV range decreased with an increase in the allophane content, whereas those in the visible range were increased by adding 1.0% (Al/Ti ratio) allophane. As a small amount of allophane nanoparticles were highly dispersed in the titania electrodes, the dye molecules were dispersed in the electrodes without decreasing the efficiency of the electron injection from the dye to the titania conduction band. The dye molecules dispersed on the titania nanoparticle surface were capped with allophane nanoparticles which prevented desorption. The dye molecules strongly interacted with the titania nanoparticle surface and efficiently injected the excited electrons into the titania conduction band.

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