In-situ hydrogen production and storage in (0 0 2) oriented TiO2 thin films

Abstract

Hydrogen production and in-situ storage from water splitting is an attractive technology for clean energy. Here (0 0 2) oriented rutile TiO2 thin films are prepared by the hydrothermal method for photocatalytic water splitting. The H2O molecule efficiently dissociates on the high energy rutile (0 0 2) surface and the highest hydrogen production rate of 28.4 mmol h−1 g−1 is achieved in the film with the lowest density, at a rate comparable to powder TiO2 photocatalysts. The produced hydrogen is stored in-situ in the films with the help of the atomic hydrogen concentration difference between the surface and in the crystal lattice. Theoretical calculations show that water is dissociated on the rutile (0 0 2) surface with a negligible energy barrier. Hydrogen atoms diffused into the sublayers are confined in the TiO2 lattice owing to a high energy barrier for them to overcome to escape from the rutile (1 1 0) surface. The theoretical storage capacity is up to 1.2%, at room temperature and atmospheric pressure, demonstrating the potential for practical room-temperature hydrogen production and storage.