Photo-adsorption and photo-desorption of oxygen on highly hydroxylated TiO2 surfaces. Part 3.—Role of H2O2 in photo-desorption of O2

摘要: Photo-desorption of oxygen from “fully hydrated” anatase surfaces has been previously observed and ascribed to the formation subsequent decomposition hydrogen peroxide. The presence HO2 radicals detected by e.p.r. on these at 77K. To assess this process in detail adsorption H2O2 solution now studied two types samples outgassed 400 200°C, respectively, (dehydroxylated hydroxylated). Photo-decomposition into O2 H2O dehydroxylated occurs which follows a diffusion law while kinetics change pseudo-zero-order higher coverages hydroxylated surfaces. E.p.r. spectra show existence “residual O–2” species dark new O–2 under u.v. illumination 77 K. Results are discussed basis our previous work confirming as an intermediate photo-adsorption/photo-desorption occurring TiO2