DFT Study of the Electronic Properties of LaOCl Surfaces

We use density functional theory to study the properties of low index flat faces (i.e., not having steps) of lanthanum oxychloride LaOCl. We calculate the surface energies and the energies to make oxygen and chlorine vacancies on the surface by producing 1/2O(2) or 1/2Cl(2) in the gas phase. We find that the electrons left behind when the vacancies are formed are localized at the vacancy site, making these sites very reactive with electrophiles. It is also possible to make Cl vacancies by a spillover process (a Cl atom leaves its lattice site to move onto the surface) but these vacancies are not chemically active. We show that p-doping, with dopants having lower valence than La, will facilitate oxygen or chlorine vacancy formation.