Structural Features and Their Relation with Catalytic Properties of Bi2WO6/TiO2–N Composites Upon Photo-Oxidation of Benzene Vapors

We consider the influence of the composition based on the nitrogen-doped titanium dioxide of a composite photocatalyst for hydrothermal synthesis on the structure adopted by the orthorhombic bismuth tungstate supported by titanium dioxide nanocrystallites. The structural features, composition, surface conditions, optical and electrochemical characteristics of the samples are studied by X-ray diffraction, X-ray photoelectron spectroscopy, nitrogen porosimetry, UV-Vis spectroscopy of diffuse surface reflections and subsequent Tauc analysis, electrochemical recording of photocurrent characteristics, and by registering the Nyquist diagrams. Catalytic tests in the test reaction of benzene vapor oxidation on synthesized photocatalysts are conducted in a flow-type reactor at the initial benzene concentrations of 2 µmol/L, 5 µmol/L, 10 µmol/L and the temperature of 40 °C under ultraviolet and blue light from LED optical radiation sources. The photocatalytic activity of the samples is estimated by the stationary steady-state rate of CO2 (final product of benzene vapor oxidation) accumulation. Based on the obtained data, the structure of the phases in the synthesized catalysts are determined and the boundaries beyond which the formation of the bismuth tungstate phase proceeds with features that affect the structure of the resulting composite and its photocatalytic activity are determined.