“…Furthermore, single-crystalline ZnO displays efficient electron transport collection and a faster charge transfer for its 2/3-fold electron mobility than TiO 2 . As a result, singlecrystalline ZnO with a variety of sizes and shapes have been prepared, including nanowires [3,4], nanofiber [5], nanodiscs [6], nanorods [7,8], nanotubes [9,10], nanonails [11], coreshell [12], and hierarchical structures [13,14]. Now, one-dimensional (1D) ZnO nanostructures such as nanowires and nanotubes have been prepared to reduce recombination phenomena upon the electron transport process and improve the electron collection efficiency [15].…”