title: Secondary branching and nitrogen doping of ZnO nanotetrapods: building a highly active network for photoelectrochemical water splitting.
abstract: A photoanode based on ZnO nanotetrapods, which feature good vectorial electron transport and network forming ability, has been developed for efficient photoelectrochemical water splitting. Two strategies have been validated in significantly enhancing light harvesting. The first was demonstrated through a newly developed branch-growth method to achieve secondary and even higher generation branching of the nanotetrapods. Nitrogen-doping represents the second strategy. The pristine ZnO nanotetrapod anode yielded a photocurrent density higher than those of the corresponding nanowire devices reported so far. This photocurrent density was significantly increased for the new photoanode architecture based on the secondary branched ZnO nanotetrapods. After N-doping, the photocurrent density enjoyed an even more dramatic enhancement to 0.99 mA/cm(2) at +0.31 V vs Ag/AgCl. The photocurrent enhancement is attributed to the greatly increased roughness factor for boosting light harvesting associated with the ZnO nanotetrapod branching, and the increased visible light absorption due to the N-doping induced band gap narrowing of ZnO.
authors.affiliation: Nano Science and Technology Program, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, PR China.
authors.forename: Yongcai
authors.initials: Y
authors.lastname: Qiu
authors.forename: Keyou
authors.initials: K
authors.lastname: Yan
authors.forename: Hong
authors.initials: H
authors.lastname: Deng
authors.forename: Shihe
authors.initials: S
authors.lastname: Yang
mesh_terms: D004563:Electrochemistry / Q000379:methods; D004574:Electromagnetic Fields; D006859:Hydrogen / Q000737:chemistry*; D008027:Light; D008422:Materials Testing; D049329:Nanostructures / Q000737:chemistry* / Q000528:radiation effects; D009584:Nitrogen / Q000737:chemistry* / Q000528:radiation effects; D010100:Oxygen / Q000737:chemistry*; D010316:Particle Size; D014025:Titanium / Q000737:chemistry*; D014867:Water / Q000737:chemistry*; D015034:Zinc Oxide / Q000737:chemistry* / Q000528:radiation effects
chemical_list: D014867:Water; C009495:titanium dioxide; D006859:Hydrogen; D014025:Titanium; D009584:Nitrogen; D010100:Oxygen; D015034:Zinc Oxide