On the properties of binary rutile MO2 compounds, M = Ir, Ru, Sn, and Ti: A DFT study

Abstract

We have studied the properties of bulk and different surfaces of rutile oxides, IrO2, RuO2, SnO2, and TiO2, and their binary compounds by means of density functional theory. As mixtures are employed in many applications, we have investigated the solubility, segregation, and overlayer formation of one of these oxides on a second metal from the series, as these aspects are critical for the chemical and electrochemical performances. Our results show that the bulk solubility is possible for several combinations. The electronic structure analysis indicates the activation of Ir states in Ir(x)Ti(1-x)O2 mixtures when compared to the parent IrO2 compound or the reduction in the band gap of TiO2 when Sn impurities are present. Segregation and oxygen-induced segregation of the second metal for the most common surfaces show a great extent of possibilities ranging from strong segregation to antisegregation, which depends on the oxygen ambient. The interaction of guest rutile overlayers on hosts is favourable and a wide range of growth properties (from multilayer formation to tridimensional particles) can be observed. Finally, a careful comparison with experimental information is presented, and for those cases where no data is available, the computed database can be used as a guideline by experimentalists.

Periodic DFT Study of Rutile IrO2: Surface Reactivity and Catechol Adsorption

“…Wulff structure is in perfect agreement with previous works 22,24 . This is explained by the fact that PBEsol overstabilizes the bulk compared to the surfaces rendering then a higher value for the surface energy.…”

“…Sen et al 24 have used DFT to parametrize a force field for IrO 2 nanoparticles. Novell-Leruth et al 22 have studied the mixture of different rutile oxides and give a brief description of the structural and energetic properties for IrO 2 surfaces.…”

“…The most stable termination is the (110). This surface was characterized both experimentally 20,21 and by means of DFT 22 , and almost all theoretical studies are focused on it. A combination of surface science and Density Functional Theory (DFT) has been used to support the stability of the oxygen rich (100) iridia termination 23 .…”

Magnetism of Zn-doped SnO2: Role of surfaces

“…37 This slight difference is presumably due to the self-interaction error in solids with local density approximation/GGA 38,39 as shown in the density of states for the rutile phase of bulk SnO 2 . The undoped bulk SnO 2 , symmetric and asymmetric slabs of (001) and (110) surfaces were found to be non-magnetic, which compares well with previous theoretical 26,28,36 and experimental 42,43 observations.…”

“…Electronic mail: pushparaghani@boisestate.edu. metallic Sn and molecular oxygen (O 2 ) is À4.39 eV, which compares well with the value À4.51 eV 36 obtained from a previous DFT-GGA calculations and the experimental value of À5.99 eV/SnO 2 . 37 This slight difference is presumably due to the self-interaction error in solids with local density approximation/GGA 38,39 as shown in the density of states for the rutile phase of bulk SnO 2 .…”