No abstract

Ag 3 PO 4 -TiO 2 -graphene oxide ternary composite photocatalysts were fabricated by the photocatalytic reduction and ion exchange methods. The properties and photocatalytic activity of the composites were examined, and the photodegradation mechanism was investigated. More TiO 2 nanoparticles in the composites were found to improve light absorption, but caused a larger impedance and inferior charge transport. Excess TiO 2 nanoparticles distributed over the surfaces of Ag 3 PO 4 and graphene oxide decreased the specific surface area and thus lowered light absorbance. an appropriate TiO 2 content enhanced photocatalytic performance. When the molar ratio of Ag 3 PO 4 to TiO 2 was 0.6, the highest efficiency in photodegradation, hydrogen production (with a quantum efficiency of 8.1% and a hydrogen evolution rate of 218.7 µmole·g −1 ·h −1 ) and bacterial inactivation was achieved. Trapping experiments demonstrated that superoxide radicals and holes are the major active species involved in the photodegradation process.

Ag‐TiO2‐graphene (ATG) ternary nanocomposites with various Ag contents were synthesized at fixed mixing ratios of TiO2 to graphene. The successful fabrication of them was confirmed by XRD, SEM, TEM, Raman and XPS spectra. The stronger Raman signals caused by the increased Ag content were considered as a significant evidence for the SPR effect. An increased Ag content gave rise to not only a wider absorption range but also a higher visible‐light absorbance. The results of electrochemical analysis illustrated that more Ag loading caused a reduced interfacial impedance, and improved conductivity and electron transport. However, excess Ag nanoparticles led to agglomeration and decreased surface area unfavorable to light absorption. Thus, an appropriate Ag content was required to achieve higher optical response and photocatalytic efficiency. It was found that for each fixed mixing ratio of TiO2 and graphene, there was a corresponding optimum Ag content. The hydrogen evolution results displayed the same trend as photodegradation, indicating again that the optimum ratio of TiO2 and graphene was 5: 1, and the extent of Ag loading was really crucial. By appropriate ratios of graphene and Ag, A15TG(5) exhibited the highest efficiency in both photodegradation and hydrogen evolution. Its QE and mass‐normalized hydrogen evolution rate were 26.2% and 705.6 μmol⋅g−1⋅h−1, respectively. Furthermore, the ATG nanocomposites also showed promising capability for bacterial inactivation.