Photochemical synthesis of SnO2/TiO2 composite nanotube arrays with enhanced lithium storage performance

Abstract

Nanostructured SnO2/TiO2 hybrid materials can be promising anode materials for lithium ion batteries (LIBs). We herein report a novel and energy-saving photodeposition approach to fabricate SnO2/TiO2 composite nanotubes. In the photodeposition process, Sn2+ ions are oxidized to SnO2 by the photogenerated holes, thus SnO2 nanoparticles are deposited onto both the inner and outer walls of TiO2 nanotubes. This results in the formation of the SnO2/TiO2 composite nanotubes with a hierarchically porous architecture. The existence of the positive bias can enhance the photooxidation of Sn2+ ions by decreasing the hole–electron recombination, leading to the deposition of more SnO2 nanoparticles on the walls of TiO2 nanotubes. The SnO2/TiO2 composite film electrode fabricated by the photodeposition at the positive bias shows much higher lithium storage capacity than the corresponding controllable electrodes during the electrochemical cycling at a current density of 100 μA cm−2. The specific capacity of SnO2 in the composite film electrode photodeposited at the positive bias is estimated to be 766 mAh g−1 after 100 cycles at a current density of 100 μA cm−2, demonstrating its prominent lithium storage performance. The as-constructed facile and energy-saving photodeposition method can be used as an efficient route to prepare other composite materials with controlled morphologies and dimensions.