Exfoliation of titanium oxide powder into nanosheets using hydrothermal reaction and its reassembly into flexible papers for thin-film capacitors

We have discovered a methodology to realize the fabrication of flexible metal oxide film using two-dimensional (2D) nanosheets. Atomic scale titanium oxide (TiOx) nanosheets were exfoliated from bulk TiOx powder that had a layered structure via the modified Sasaki's method. The vacuum-assisted filtration generates films with laterally aligned TiOx nanosheets. The 2D sheet-like structure and hydrophilic nature of TiOx nanosheets enables the film consisting of TiOx nanosheets to be bendable. Also, we demonstrate the fabrication of electrochemical capacitors using this film. The mechanically flexible metal oxide film is expected to open up the possibility of fabricating flexible energy storage devices from 2D metal oxide nanosheets. (C) 2014 Elsevier Inc. All rights reserved.