A Novel Photoanode with Three‐Dimensionally, Hierarchically Ordered Nanobushes for Highly Efficient Photoelectrochemical Cells

Abstract

In recent years, photoelectrochemical (PEC) cells have attracted worldwide attention as cheap alternatives to conventional devices for solar energy conversion. Crucial to the light harvesting and conversion effi ciency of a PEC cell is a nanostructured photoanode, in which the incident photons are captured, electron–hole pairs are generated, and the subsequent electron transfer takes place. [ 1 , 2 ] To realize highly effi cient PEC cells, a nanostructured photoanode should possess several favorable intrinsic characteristics, such as adequate specifi c surface area to permit high photosensitizer loading (in the case of TiO 2 ), direct electron transport pathways for long electron diffusion length, and strong light scattering to promote the light harvesting ability by confi ning the light within the cell. [ 3–6 ] It is thus highly desirable to develop a photoanode that meets all the above requirements. Towards this goal, immense efforts have been concentrated on tailoring the nanometer-scale features of photoanode materials. [ 7 ] Nanoparticle fi lms provide very high surface areas to increase the amount of sensitizer loading, but they lack direct electrical contacts and light-scattering ability. [ 8 , 9 ]