Polyoxometalate/TiO2/Ag composite nanofibers with enhanced photocatalytic performance under visible light

Abstract The exploration of highly efficient and stable visible-light-driven photocatalysts for the wastewater treatment has been recognized as one of the currently most challenging topics for the environment remediation. In this paper, we report a new type of polyoxometalate-TiO 2 composite nanofibers loaded with Ag nanoparticles (NPs), labeled as PMo 12 /TiO 2 /Ag-X (PMo 12  = [PMo 12 O 40 ] 3− ; X represents the weight percent (%) of Ag in PMo 12 /TiO 2 /Ag samples; X = 3.98, 5.41, 6.83, and 7.19 respectively). The SEM and TEM images manifest that the average diameter of the PMo 12 /TiO 2 composite fibers is about 130 ± 30 nm, and the average size of Ag NPs is about 15 ± 5 nm. Photocatalytic experiments confirm that PMo 12 /TiO 2 /Ag catalysts display highly efficient and durable activity for the photodegradation of methyl orange (MO) and photoreduction of Cr(VI) under visible light irradiation (λ > 420 nm). In these composite series, PMo 12 /TiO 2 /Ag-5.41 exhibits the highest photocatalytic activity. The photocatalytic mechanism reveals that both Ag and PMo 12 can be excited under visible light irradiation, which greatly improves the visible-light absorption of the composites. Furthermore, the introduction of POM species can not only improve the light adsorption and redox activity of the TiO 2 , but also promote the photochemical stability of the plasmonic composites because of the relatively narrow band gap and low reversible redox potential of polyoxoanion. Such POMs-based plasmon photocatalysts are important in ongoing efforts to designing and exploring of new photocatalytic materials with low cost, high efficiency, and durability.