Visible-Light Responsive Photocatalytic Wastewater Fuel Cell Based On TiO₂ Nanotube Arrays

It is difficult for traditional wastewater treatment method to dispose those pollutants with high efficiency. The photocatalytic oxidation technologyis promising in organic pollutant treatment. Compared with conventional treatment processes, it has advantages of energy-saving property, non-secondary pollutionand complete mineralization of refractory organic pollutants. Based on these, a visible-light driven wastewater photocatalytic fuel cell system（WPFC） comprising WO₃/TiO₂ and Cu O/TiO₂ nanotubes materials as photoanode and photocathode, was established with a dual objective of degrading an organic water pollutant, disinfecting bacteria and generating electric power as well.In this paper, TiO₂ nanotube arrays electrode were fabricated by anodization, based on this electrode, WO₃/TiO₂ nanotube arrays and Cu O/TiO₂ nanotube arrays was synthesized by cathodic square-wave method and potentiostatically polarization,respectively. Combining with Scanning electron microscope（SEM）, X-ray diffraction（XRD）, Optical diffuse-reflection spectra（DRS） and some other testing methods, the structure, morphology and optical absorption properties of the two electrodes were analyzed.The electrochemical testing was used to characterize the electrochemical properties of the electrodes and PFC system. Under illumination（60 W incandescent lamp）, the Fermi level of WO₃/TiO₂ nanotube arrays photoanode was negative than that of Cu O/TiO₂ nanotube arrays photocathode. Arising an interior bias（0.18 V） induced the transfer of electrons from the photoanode across the external circuit to the photocathode and the electron/hole pair separations at two photoelectrodes are facilitated to release the holes of WO₃/TiO₂ photoanode.Organic compound degradation and Bacteria disinfection were used to test the photocatalytic performance. Using the WPFC system of WO₃/TiO₂-Cu O/TiO₂, the degradation of an organic water pollutant（Rhodamine B） was a degradation pathway of the whole conjugated chromophore cleavage. The decolorization and TOC removal were obtained to the extent of 100% and 57% respectively at 4 h reaction time, which was much better than the other systems（TiO₂-Cu O/TiO₂ WPFC system; WO₃/TiO₂ 、 Cu O/TiO₂system）. With regard to the disinfection, the results confirm that E. Coli can be successfully inactivation in WO₃/TiO₂-Cu O/TiO₂ WPFC system, all the E. Coli could be killed after 50 min.