Full-spectrum-visible-light photocatalyst based on the active layer of organic solar cell - Towards water splitting and volatile molecule degradation-

Abstract

The photocatalytic degradation of organic compounds on a semiconducting TiO2 surface under UV irradiation offers a practical solution to a variety of environmental problems. However, a major disadvantage is the band gap of anatase TiO2 of 3.3 eV, which requires excitation wavelengths of UV light of less than 380 nm. Although, other photocatalysts exhibit a high reactivity using visible light, few visible-light-activated photocatalysts have been developed that cover the entire visible region. An organic pn-bilayer composed of a perylene derivative (3,4,9,10- perylenetetracarboxylbisbenzimidazole, PTCBI) and phthalocyanine (H 2Pc) is typically used as the photovoltaic material in a dry solar cell. This combination works in wet conditions as a photoanode and photocathode for ITO/PTCBI/H2Pc/electrolyte and ITO/H2Pc/PTCBI/ electrolyte, respectively. Moreover, oxygen evolution occurred with a small bias (ca. +0.4 V vs. Ag/AgCl) under visible-light illumination, particularly by loading an IrO2 catalyst on the H2PC surface or inserting cobalt ion into the phthalocyanine. By combining with a Nafion membrane, H 2PC/PTCBI was responsive to the entire visible light region (<780nm), and the first example of oxygen-tolerable and oxygen-useable photocatalyst consisting of only organic materials. Trimethylamine was removed and completely oxidized in both, gas and water phase. The external quantum efficiency of CO2 generation per incident photon (EQEC02) was estimated to be 0.4. Biphasic nanoparticles composed of p-type and n-type semiconductors were synthesized using a low-cost fabrication by reprecipitation. The composite also showed photocatalytic oxidation of organic volatiles to CO2 for almost the full spectrum of visible light. Such efficient and visible-light-responsive organophotocatalyst can be used under interior light conditions. © 2013, The Society of Polymer Science, Japan.