6533b872fe1ef96bd12d4334

RESEARCH PRODUCT

Preparation characterization and photocatalytic activity of polycrystalline ZnO/TiO2 systems. 2. Surface, bulk characterization, and 4-nitrophenol photodegradation in liquid-solid regime

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Electron spin resonance spectroscopy (ESR), Fourier transform infrared spectroscopy (FTIR), and monitoring of pyridine (py) and boric acid trimethyl ester (BATE) adsorption for determining surface acidity and basicity, respectively, were used to carry out further characterization of mixed ZnO/TiO2 polycrystalline solids prepared by different methods. Moreover, the powders were tested in a batch photoreactor for a probe reaction, i.e., 4-nitrophenol photodegradation in aqueous medium. ESR results indicated the presence of signals attributable to Zn+ species in ZnO/TiO2 (anatase) solids, while in ZnO/TiO2 (rutile) samples the presence of zinc induced only the formation of signals probably due to Ti3+ centers. FT-IR spectra showed no significant differences of the surface hydroxylation degree of the various photocatalysts, whereas the surface acidic properties generally decrease by increasing the amount of ZnO. Coupling of ZnO and TiO2 semiconducting powders was not so beneficial, as expected on the basis of...