Comparison and understanding of the different simulated sunlight photocatalytic activity between the saturated and monovacant Keggin unit functionalized titania materials

The saturated and monovacant Keggin unit functionalized titania materials, H3PW12O40/TiO2 and K7PW11O39/TiO2, were prepared by one step sol–gel co-condensation followed by solvothermal treatment. The structure, optical absorption properties, morphology, and porosity of the materials were well characterized. Subsequently, their simulated sunlight photocatalytic activity was evaluated by the degradation and mineralization of dye rhodamine B (RB) and endocrine-disrupting chemical diethyl phthalate (DEP). Special attention was paid to provide direct evidences for the explanation of the different photoexcited electron–hole pair separation rates of the H3PW12O40/TiO2, K7PW11O39/TiO2, and pure TiO2 by the photoelectrochemical experiment; simultaneously, the target active species yielded in the K7PW11O39/TiO2- and H3PW12O40/TiO2-catalyzed DEP degradation systems were also investigated by the free radical and hole scavenging experiment. Accordingly, reasons for the photocatalytic activity difference between the K7PW11O39/TiO2 and H3PW12O40/TiO2 as well as pure TiO2 were revealed.