First-Principles Study on Water and Oxygen Adsorption on Surfaces of Indium Oxide and Indium Tin Oxide Nanoparticles

We present a first-principles study on surface structures of In 2 O 3 and indium tin oxide (ITO) nanoparticles upon exposure to O 2 and H 2 O molecules. It was found that dissociative chemisorption of O 2 and H 2 O is facile on the metal-terminated oxide surfaces. O 2 chemisorption is energetically more favorable than H 2 O dissociative chemisorption until the metal-terminated surfaces are saturated by chemisorbed O 2 dimers, at which point the surfaces become virtually identical to the O-terminated surfaces and the dissociative chemisorption of H 2 O becomes the energetically preferred process. The calculated surface structures and the surface states as represented by the density of states spectra are in good agreement with experimental surface characterizations and the UPS photoelectron spectra of In 2 O 3 and ITO thin films.