An unexpected interaction between a H2O2 molecule and anatase TiO2(101) surface

In this paper, the interactions between a H₂O₂ molecule and anatase TiO₂(101) (A-TiO₂) surface are studied by first-principle calculations. It is found that a H₂O₂ molecular can adsorb or dissociate on A-TiO₂(101) surface, in agreement with previous results. When a H₂O₂ molecule dissociates, Ti-μ-peroxide configurations may form. It should be noticed that a more stable Ti-μ-peroxide configuration is found in this paper. More interestingly, an oxygen atom of this dissociated H₂O₂ can enter into A-TiO₂(101) lattice, i.e., forming surface (O₂)o. The energy barriers for formations of new Ti-μ-peroxide and surface (O₂)o species are 0.30 and 1.28 eV, respectively, which explain previous experimental results that the formations of Ti-μ-peroxide and (O₂)o species are under lower and higher temperatures, respectively. The localized gap state of Ti-μ-peroxide disappears after the formation of surface (O₂)o, and thus the recombination probability of electron-hole pairs should be reduced for the O-rich A-TiO₂. These results can rationalize experimental results that the photocatalytic activity of A-TiO₂ sample can be changed by H₂O₂ treating under different temperature.