Photocatalysis, a promising technology platform to address the environmental problems, has been attracting considerable attention. In this paper, Ag/AgHPMoO (simplified as Ag/AgHPMo) nanowires have been synthesized by a facile solid reaction route and in situ photodeposited method. The results of SEM and TEM indicate that the diameters of AgHPMo nanowires are about 45 ± 10 nm, and Ag nanoparticles with diameters in the range of 5-15 nm are uniformly anchored on the surface of AgHPMo nanowires. The Ag content in the Ag/AgHPMo composite was manipulated by the light irradiation time (Ag/AgHPMo-x; x stands for the irradiation time; x = 2, 4, 6, 8 h, respectively). With increasing irradiation time, the light absorption of as-synthesized samples in the visible region was gradually enhanced. The Ag/AgHPMo-4 exhibits the best photocatalytic performance for the degradation of methyl orange and reduction of CrO under visible-light (λ > 420 nm) irradiation. The study of the photocatalytic mechanism reveals that both Ag and AgHPMo can be excited by visible light. The photoinduced electrons were transferred from AgHPMo to metallic Ag, and combined with the Ag plasmonic holes. The Ag plasmonic electrons were trapped by O to form ·O, or directly reduced CrO to Cr. Meanwhile, the ·O species and the photogenerated holes of AgHPMo were used to oxidize MO or i-PrOH; thus, they showed highly efficient and recyclable photocatalytic performance for removing the organic and inorganic pollutants.
Carbon nitride (g-CN), as a rising star of metal-free photocatalysts, has received considerable attention. However, for practical application, the photocatalytic efficiency of g-CN remains to be further improved. Herein, a series of Keggin-type polyoxoanion (polyoxoanions = SiWO, PWO, PMoO) modified g-CN (POM/CN) composites have been successfully prepared. The results of XRD, TEM, XPS and EDAX reveal that a small amount of polyoxoanions was modified on the surface of g-CN with electrostatic and hydrogen bonding interactions. Photocatalytic experiments indicate that these composites exhibit enhanced methyl orange (MO) degradation photocatalytic activity and water splitting H production under visible light irradiation. The loading amount and the type of polyoxoanion can tune the photocatalytic performance of the composites. Among these catalysts, 5% SiWO (SiW)-modified g-CN has the best photocatalytic performance, which is 4.4 times higher than that of pure g-CN for the degradation of MO. The photocatalytic mechanism reveals that polyoxoanions can act as electron traps, which can efficiently promote the separation of photogenerated electrons and holes of CN, thus resulting in the enhanced photocatalytic performance of the composites.
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