Reaction in photofuel cells using allophane–titania nanocomposite electrodes

•Allophane–titania photofuel cell electrodes were prepared by a sol–gel method.•Photocatalytic oxidation of starch was observed in the solutions and suspensions.•The oxidation of starch enhanced the generation of electricity.•Allophane increased the capacity of the electrode to adsorb the starch molecules.•Allophane brought the starch molecules close to the titania nanoparticles. Allophane–titania nanocomposite electrodes for photofuel cells were prepared from titanium alkoxide sols dispersing the natural clay mineral allophane. The electrochemical measurements indicated that the oxidative degradation of starch in the solutions and suspensions enhanced the generation of electricity during UV irradiation. CO2 was observed as the degradation product. A higher photocurrent was observed using the allophane–titania nanocomposite electrode adsorbing a greater amount of the starch molecules. Allophane increased the capacity of the electrode to adsorb the starch molecules, even from the suspensions. This brought the molecules close to the titania nanoparticles, on which their oxidation induced the generation of electricity.