Three-dimensional nanoporous TiO2 network films with excellent electrochemical capacitance performance

•A 3D nanoporous hydrogenated TiO2 network film was fabricated by a novel method.•The 3D nanoporous network consists of the interconnected long TiO2 nanotubes.•The 3D nanoporous H-TiO2 network film exhibits prominent capacitance properties.•Hydrogenation obviously improves the electrical conductivity of TiO2 network film.

The three-dimensional (3D) nanoporous hydrogenated TiO2 (denoted as H-TiO2) network film on titanium substrate was fabricated by a novel and controllable method. The fabrication process involved dealloying, alkaline reflux and hydrogenation. The dealloying produced the 3D nanoporous titanium film with open pores and interconnected nanoflakes nearly perpendicular to the substrate. The oxidation of the 2D titanium nanoflakes in the alkaline reflux resulted in the formation of the TiO2 nanotubes with an inner diameter of 5–10 nm and a length larger than 1.5 μm. The 3D nanoporous TiO2 network film was formed by the self assembly of these long and thin TiO2 nanotubes. Hydrogenation induced the formation of oxygen vacancies and more hydroxyl groups on the H-TiO2 surface. The 3D nanoporous H-TiO2 network film presented a capacitance of 1.05 mF cm−2 at the scanning rate of 100 mV s−1. Furthermore, the H-TiO2 network film electrode also showed remarkable rate capability as well as excellent electrochemical cycling stability with a capacitance reduction of less than 7% after 1000 charge–discharge cycles at the current density of 100 μA cm−2. The prominent electrochemical capacitance properties of the 3D H-TiO2 network film electrode could be attributed to its unique structural characteristics.

Graphical abstractThe as-constructed three-dimensional (3D) nanoporous hydrogenated TiO2 network film, which consists of the interconnected long and thin TiO2 nanotubes, exhibits the prominent electrochemical capacitance properties, especially at a high current rate.Figure optionsDownload full-size imageDownload as PowerPoint slide