In the present work novel, ternary semiconductor composites were prepared by applying
the pH adjustment method (the WO3 based components were obtained separately, while
TiO2 was a commercial one), where the pH was fine-tuned to 1, 4, 7 and 10.The composition
of the prepared samples was in each case 76% commercial TiO2 (Evonik Aeroxide P25),
12% monoclinic (WO3) and 12% hexagonal partial hydrate (WO3 center dot 0.33H(2)O).
All the composites showed improved UV light-driven photocatalytic activity compared
to P25 in the degradation of methyl orange, oxalic acid and activity inhibition was
observed in the case of phenol degradation. SEM micrographs and the XRD patterns of
the samples proved that all three components were successfully integrated into the
composite system. DRS spectra of the samples provided evidence concerning a mutual
interaction of the composite components modifying their electronic structure, while
the effect of the synthesis pH was also visible in the IR spectra. Raman Spectroscopy
proved the presence of surface defects, manifested through the presence of (W5+ centers).
Moreover, interesting correlations were found between several Raman peak intensity
ratios (I-324/I-714; I-943/I-805) and the photoactivity pointing the importance of
the W5+ centers and amorphous WO3 formed under basic conditions.