Application of reactivity descriptors to the catalytic decomposition of hydrogen peroxide at oxide surfaces

We have employed density functional theory (DFT) calculations using the PBE0 functional to study the reaction of decomposition of H2O2 on clusters of: ZrO2, TiO2, Y2O3, Fe2O3, CeO2, CuO, Al2O3, NiO2, PdO2 and Gd2O3. The formation of the products of decomposition of H2O2 and their binding onto these oxides are discussed. The obtained energy barriers for H2O2 decomposition deviate from experimental data in absolute average by 4kJmol−1. The only exceptions are CeO2 and Fe2O3 for which the deviations are very large. The adsorption of HO radicals onto the clusters was also studied. Reactivity descriptors obtained with DFT calculations are correlated with experimental data from literature. We found a direct correlation between the adsorption energy of HO radicals and the change in Mulliken charge of the cation present in the oxide, upon adsorption of these radicals. Other DFT and experimentally obtained reactivity descriptors based on properties of the cations present in the oxides, such as the ionization potential and electronegativity are plotted against experimental and DFT computed properties, respectively. Following the Brønsted–Evans Polanyi principle, there is a correlation between the adsorption energy of the product HO radical and the energy barrier for decomposition of H2O2. The good correlations between experimental data and the data obtained with DFT using minimalistic cluster models of the oxides surfaces indicates that on the real systems the processes that determine the reactivity of H2O2 are very dependent on localized properties of the surfaces.