Oleg I. Silyukov

Photocatalytic properties and hydration of perovskite-type layered titanates A2Ln2Ti3O10 (A = Li, Na, K; Ln = La, Nd)

Layered perovskite-type oxides A2Ln2Ti3O10 (A = Li, Na, K; Ln = La, Nd) prepared by solid-phase synthesis and their hydrated forms were characterized by the methods of TGA, XRD, and by UV-Vis spectroscopy. Photocatalytic activity of A2Ln2Ti3O10 oxides in reaction of hydrogen evolution from aqueous alcoholic suspensions irradiated by UV-light was studied. It was shown that the ability to intercalation of water into interlayer space essentially affects the rate of photoinduced hydrogen evolution and is a determining factor leading to a high photocatalytic activity.

Ion-Exchange Reactions in the Structure of Perovskite-like Layered Oxides: I. Protonation of NaNdTiO 4 Complex Oxide

The behavior of perovskite-like NaNdTiO4 complex oxide in acid aqueous solutions was studied. By the X-ray and thermogravimetry analyses the instability of NaNdTiO4 in aqueous solutions was found, which is determined by the sodium cation exchange for protons and by water molecules intercalation into the interlayer space of the crystal structure. The proton-containing layered oxides HNdTiO4 and HxNa1−xNdTiO4·yH2O were obtained (1 < x < 0.64, 0 < y < 0.47). The structure of the H0.73Na0.27NdTiO4·0.3H2O compound was refined.

Soft Chemistry Synthesis of Complex Oxides Using Protonic Form of Titanates HLnTiO4 (Ln=La, Nd)

In the present work protonic forms of layered n=1 Ruddlesden-Popper oxides HLnTiO4 (Ln=La, Nd) were used as starting point for synthesis of three series of the perovskite-like compounds. Characterization by SEM, powder XRD and TGA has been performed for the determination of the structure and composition of synthesized oxides.

Study of photocatalytic activity of layered oxides: NaNdTiO4, LiNdTiP4, and HNdTiO4 titanates

The catalytic activity of the perovskite-like layered oxides NaNdTiO4, LiNdTiO4, and HNdTiO4 in the reaction of the methyl orange dye decomposition under the action of UV irradiation was studied. Rate constants of the pseudo-first order were determined. It was found that in the series NaNdTiO4, HNdTiO4, and LiNdTiO4 the photocatalytic activity of the layered oxides increases.

Low-temperature transformations of protonic forms of layered complex oxides HLnTiO 4 and H 2 Ln 2 Ti 3 O 10 (Ln = La, Nd)

In the present work protonic forms of layered n = 1,3 Ruddlesden-Popper oxides HLnTiO4 and H2Ln2Ti3O10 (Ln = La, Nd) were used as the starting point for soft chemistry synthesis of two series of perovskite-like compounds by acid leaching and exfoliation, promoted by vanadyl sulfate. The last route leads to the nanostructured VO2+ containing samples. Characterization by SEM, powder XRD, and TGA has been performed for the determination of the structure and composition of synthesized oxides.

Synthesis of Protonated Derivatives of Layered Perovskite-Like Bismuth Titanates

The possibility of synthesizing protonated derivatives of layered perovskite-like titanates Bi4Ti3O12, ABi4Ti4O15, (A = Ba, Sr, Ca) and K2.5Bi2.5Ti4O13 is experimentally investigated. It is established that in the case of Bi4Ti3O12 and ABi4Ti3O15, single-phased protonated derivatives cannot be obtained by treating the compounds with acid solutions, due to the partial dissolution of initial oxides, accompanied by the formation of titanium dioxide. In the case of K2.5Bi2.5Ti4O13 titanate, a number of new protonated and hydrated derivatives are obtained and described.

Protonation and Photocatalytic Activity of the Rb2La2Ti3O10 Layered Oxide in the Reaction of Hydrogen Production

The Rb2La2Ti3O10 layered oxide was synthesized by the solid-state method. Three phases with different protonation degrees and intercalated water contents were obtained from the initial compound by the treatment with distilled water and hydrochloric acid. The obtained samples were characterized by powder X-ray diffraction, SEM, X-ray microanalysis, BET, DRS, and TG. It was found that the complete ion exchange of Rb