The development of visible-light active titanium dioxide is one of the key challenges in photocatalysis that stimulates the development of TiO2-based composite materials and methods for their synthesis. Here, we report the use of pristine and Pt-modified dark titanium dioxide prepared via pulsed laser ablation in liquid (Nd:YAG laser, 1064 nm, 7 ns) for photocatalytic hydrogen evolution from alcohol aqueous solutions. The structure, textural, optical, photoelectrochemical, and electrochemical properties of the materials are studied by a complex of methods including X-ray diffraction, low-temperature nitrogen adsorption, electrophoretic light scattering, diffuse reflection spectroscopy, photoelectrochemical testing, and electrochemical impedance spectroscopy. Both the thermal treatment effect and the effect of modification with platinum on photocatalytic properties of dark titania materials are studied. Optimal compositions and experimental conditions are selected, and high photocatalytic efficiency of the samples in the hydrogen evolution reaction (apparent quantum yield of H2 up to 0.38) is demonstrated when irradiated with soft UV and blue LED, i.e., 375 and 410 nm. The positive effect of low platinum concentrations on the increase in the catalytic activity of dark titania is explained.

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Normal 0 false false false RU X-NONE X-NONE The combination of methods of voltammetry, Raman spectroscopy, and X-ray reflectometry for the first time has been applied for the more comprehensive investigation of interfacial boundaries of GaAs, i.e. determination of phase distribution and thickness of the phase layers. The conditions for the formation of elemental arsenic on a GaAs surface in the process of selective dissolution are discussed. The stability of interfacial boundaries in air has also been studied. The investigations have shown that air storage lead to the oxidation of formed As0 and reorganization of GaAs interfacial boundary accompanied by the formation of Ga2O3 and As0 as a result of a reaction between As2O3 and GaAs. The results on interfacial boundaries composition were found to be correlated with the theoretical data. /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Обычная таблица"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin-top:0cm; mso-para-margin-right:0cm; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0cm; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi; mso-fareast-language:EN-US;}

This study is devoted to understanding the thermodynamic basis of the process of synthesis of ZnS, CdS and their solid solutions in aqueous solutions in order to obtain thin films of required composition. The typical interfacial reactions were considered, and the thermodynamic calculations of the possible redox reactions and the reaction standard electrode potentials have been done. The composition of a solution is analyzed by means of thermodynamic diagrams as a function of redox potential versus pH. It has been demonstrated that the near-surface layer with the defect structure and the excess of sulfur on a surface can be formed in case of ZnS at pH < 1.5 during the synthesis. The application of obtained data in the synthesis of semiconducting materials is also shown.