Oriented Assembled TiO2Hierarchical NanowireArrays with Fast Electron Transport Properties.

Developinghigh surface area nanostructured electrodes with rapidcharge transport is essential for artificial photosynthesis, solarcells, photocatalysis, and energy storage devices. Substantial researchefforts have been recently focused on building one-dimensional (1D)nanoblocks with fast charge transport into three-dimensional (3D)hierarchical architectures. However, except for the enlargement insurface area, there is little experimental evidence of fast electrontransport in these 3D nanostructure-based solar cells. In this communication,we report single-crystal-like 3D TiO2branched nanowirearrays consisting of 1D branch epitaxially grown from the primarytrunk. These 3D branched nanoarrays not only demonstrate 71% enlargementin large surface area (compared with 1D nanowire arrays) but alsoexhibit fast charge transport property (comparable to that in 1D singlecrystal nanoarrays), leading to 52% improvement in solar conversionefficiency. The orientated 3D assembly strategy reported here canbe extended to assemble other metal oxides with one or multiple componentsand thus represents a critical avenue toward high-performance optoelectronics. [ABSTRACT FROM AUTHOR]