Hydrogen Impurity Defects in Rutile TiO2

Hydrogen-related defects play crucial roles in determining physical properties of their host oxides. In this work, we report our systematic experimental and theoretical (based on density functional theory) studies of the defect states formed in hydrogenated-rutile TiO 2 in gaseous H 2 and atomic H. In gas-hydrogenated TiO 2 , the incorporated hydrogen tends to occupy the oxygen vacancy site and negatively charged. The incorporated hydrogen takes the interstitial position in atom-hydrogenated TiO 2 , forming a weak O-H bond with the closest oxygen ion and becomes positive. Both states of hydrogen affect the electronic structure of TiO 2 mainly through changes of Ti 3d and O 2p states instead of the direct contributions of hydrogen. The resulted electronic structures of the hydrogenated TiO 2 are manifested in modifications of the electrical and optical properties that will be useful for the design of new materials capable for green energy economy.