Synthesis of hierarchical TiO2 micro/nanostructure and its application in hybrid solar cell

Hierarchically micro/nanostructured rutile TiO2 is prepared by a convenient hydrothermal reaction, and characterized by XRD, SEM, and TEM (HR-TEM). The hierarchical TiO2 micro/nanostructure is highly branched and consists of a three-dimensional assembly of TiO2 nanorods. Based on the experimental evidences, a mechanism involving three growth stages is proposed for formation of the hierarchical TiO2 micro/nanostructure. The first stage is the nucleation and growth of rutile TiO2 trunk nanorods along [001] direction, the second stage is the nucleation and growth of TiO2 branch nanorods at the defect sites created by HCl corrosion on the preformed trunk surfaces, and the third stage is the continuous growth of hierarchically nanostructured TiO2 through Ostwald ripening process where some nanobranches grow larger with time accompanied by sub-branches growth and a number of smaller nanobranches disappear. Results show that the hierarchical TiO2 micro/nanostructure is a potential photovoltaic material.

► A hierarchical rutile TiO2 micro/nanostructure is prepared by hydrothermal reaction.
► HCl serves as a corrosive agent for growth of nanorod branches.
► The hierarchical micro/nanostructure grows evidently by a three-stage mechanism.
► The TiO2 micro/nanostructure is an effective photovoltaic material.