title: Photoelectrochemical water splitting strongly enhanced in fast-grown ZnO nanotree and nanocluster structures.
abstract: We demonstrate selective growth of ZnO branched nanostructures: from nanorod clusters (with branches parallel to parent rods) to nanotrees (with branches perpendicular to parent rods). The growth of these structures was realized using a three-step approach: electrodeposition of nanorods (NRs), followed by the sputtering of ZnO seed layers, followed by the growth of branched arms using hydrothermal growth. The density, size and direction of the branches were tailored by tuning the deposition parameters. To our knowledge, this is the first report of control of branch direction. The photoelectrochemical (PEC) performance of the ZnO nanostructures follows the order: nanotrees (NTs) > nanorod clusters (NCs) > parent NRs. The NT structure with the best PEC performance also possesses the shortest fabrication period which had never been reported before. The photocurrent of the NT and NC photoelectrodes is 0.67 and 0.56 mA cm-2at 1 Vvs.Ag/AgCl, respectively, an enhancement of 139% and 100% when compared to the ZnO NR structures. The key reason for the improved performance is shown to be the very large surface-to-volume ratios in the branched nanostructures, which gives rise to enhanced light absorption, improved charge transfer across the nanostructure/electrolyte interfaces to the electrolyte and efficient charge transport within the material.
authors: Research Center for Nanoscience and Technology , Shanghai University , 99 Shangda Road , Shanghai 200444 , China . Email: renxin108@shu.edu.cn ; ; Tel: +86 21 66137197.
authors: Xin
authors: X
authors: Ren
authors: Department of Materials Science and Metallurgy , University of Cambridge , 27 Charles Babbage Road , Cambridge CB3 0FS , UK . Email: jld35@cam.ac.uk ; ; Tel: +44 (0)1223334468.
authors: Abhijeet
authors: A
authors: Sangle
authors: Department of Materials Science and Metallurgy , University of Cambridge , 27 Charles Babbage Road , Cambridge CB3 0FS , UK . Email: jld35@cam.ac.uk ; ; Tel: +44 (0)1223334468.
authors: Siyuan
authors: S
authors: Zhang
authors: Research Center for Nanoscience and Technology , Shanghai University , 99 Shangda Road , Shanghai 200444 , China . Email: renxin108@shu.edu.cn ; ; Tel: +86 21 66137197.
authors: Shuai
authors: S
authors: Yuan
authors: Research Center for Nanoscience and Technology , Shanghai University , 99 Shangda Road , Shanghai 200444 , China . Email: renxin108@shu.edu.cn ; ; Tel: +86 21 66137197.
authors: Yin
authors: Y
authors: Zhao
authors: Research Center for Nanoscience and Technology , Shanghai University , 99 Shangda Road , Shanghai 200444 , China . Email: renxin108@shu.edu.cn ; ; Tel: +86 21 66137197.
authors: Liyi
authors: L
authors: Shi
authors: Department of Materials Science and Metallurgy , University of Cambridge , 27 Charles Babbage Road , Cambridge CB3 0FS , UK . Email: jld35@cam.ac.uk ; ; Tel: +44 (0)1223334468.
authors: Robert L Z
authors: RL
authors: Hoye
authors: Department of Materials Science and Metallurgy , University of Cambridge , 27 Charles Babbage Road , Cambridge CB3 0FS , UK . Email: jld35@cam.ac.uk ; ; Tel: +44 (0)1223334468.
authors: Seungho
authors: S
authors: Cho
authors: Shanghai Advanced Research Institute , Chinese Academy of Sciences , 99 Haike Road, Zhangjiang Hi-Tech Park , Shanghai 201210 , China.
authors: Dongdong
authors: D
authors: Li
authors: Department of Materials Science and Metallurgy , University of Cambridge , 27 Charles Babbage Road , Cambridge CB3 0FS , UK . Email: jld35@cam.ac.uk ; ; Tel: +44 (0)1223334468.
authors: Judith L
authors: JL
authors: MacManus-Driscoll