title: Branched TiO₂ nanorods for photoelectrochemical hydrogen production.
abstract: We report a hierarchically branched TiO(2) nanorod structure that serves as a model architecture for efficient photoelectrochemical devices as it simultaneously offers a large contact area with the electrolyte, excellent light-trapping characteristics, and a highly conductive pathway for charge carrier collection. Under Xenon lamp illumination (UV spectrum matched to AM 1.5G, 88 mW/cm(2) total power density), the branched TiO(2) nanorod array produces a photocurrent density of 0.83 mA/cm(2) at 0.8 V versus reversible hydrogen electrode (RHE). The incident photon-to-current conversion efficiency reaches 67% at 380 nm with an applied bias of 0.6 V versus RHE, nearly two times higher than the bare nanorods without branches. The branches improve efficiency by means of (i) improved charge separation and transport within the branches due to their small diameters, and (ii) a 4-fold increase in surface area which facilitates the hole transfer at the TiO(2)/electrolyte interface.
authors: Department of Mechanical Engineering, Stanford University, California 94305, United States.
authors: In Sun
authors: IS
authors: Cho
authors: Zhebo
authors: Z
authors: Chen
authors: Arnold J
authors: AJ
authors: Forman
authors: Dong Rip
authors: DR
authors: Kim
authors: Pratap M
authors: PM
authors: Rao
authors: Thomas F
authors: TF
authors: Jaramillo
authors: Xiaolin
authors: X
authors: Zheng
mesh_terms: D004574:Electromagnetic Fields; D006859:Hydrogen / Q000737:chemistry* / Q000302:isolation & purification; D008027:Light; D008422:Materials Testing; D049329:Nanostructures / Q000737:chemistry* / Q000528:radiation effects* / Q000648:ultrastructure; D014025:Titanium / Q000737:chemistry* / Q000528:radiation effects*
chemical_list: C009495:titanium dioxide; D006859:Hydrogen; D014025:Titanium