Abstract

The Pd– and Ag–doped anatase TiO <inf>2</inf> (1 0 1) surfaces were investigated and the binding energies of single atom of Pd (−2.15 eV) and Ag (−2.38 eV) on the anatase (1 0 1) surfaces, respectively denoted as Pd/TiO <inf>2</inf> and Ag/TiO <inf>2</inf> were obtained. Binding sites for Pd and Ag atoms toward the TiO <inf>2</inf> surface atoms are three atoms (Ti <inf>5C</inf> and two O <inf>2C</inf> atoms) and two O <inf>2C</inf> atoms of the TiO <inf>2</inf> (1 0 1) surface, respectively. Due to adsorptions of H <inf>2</inf> and hydrogen–containing (H <inf>2</inf> O, NH <inf>3</inf> , and CH <inf>4</inf> ) gases on the Pd/TiO <inf>2</inf> and Ag/TiO <inf>2</inf> , adsorption abilities on the Pd/TiO <inf>2</inf> and Ag/TiO <inf>2</inf> are in decreasing orders: NH <inf>3</inf> > H <inf>2</inf> O > H <inf>2</inf> > CH <inf>4</inf> and NH <inf>3</inf> > H <inf>2</inf> O > CH <inf>4</inf> > H <inf>2</inf> , respectively. Mulliken–charge transfers from the Pd and Ag atoms to adsorption atoms of the anatase TiO <inf>2</inf> (1 0 1) surface and the adsorption of hydrogen and hydrogen–containing gases to the Pd/TiO <inf>2</inf> and Ag/TiO <inf>2</inf> were observed. The Pd/TiO <inf>2</inf> and/or Ag/TiO <inf>2</inf> have high potentials to be NH <inf>3</inf> sensing materials based on the electric conductivity measurement. The Pd/TiO <inf>2</inf> has high potential to be CH <inf>4</inf> sensing device based on the electric conductivity and surface charge measurements.