Ag/Ag_xH_3-xPMo₁₂O₄₀ Nanowires with Enhanced Visible-Light-Driven Photocatalytic Performance

Photocatalysis, a promising technology platform to address the environmental problems, has been attracting considerable attention. In this paper, Ag/Ag_xH_3-xPMo₁₂O₄₀ (simplified as Ag/AgHPMo₁₂) 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 AgHPMo₁₂ 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 AgHPMo₁₂ nanowires. The Ag content in the Ag/AgHPMo₁₂ composite was manipulated by the light irradiation time (Ag/AgHPMo₁₂-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/AgHPMo₁₂-4 exhibits the best photocatalytic performance for the degradation of methyl orange and reduction of Cr₂O₇^2- under visible-light (λ > 420 nm) irradiation. The study of the photocatalytic mechanism reveals that both Ag and AgHPMo₁₂ can be excited by visible light. The photoinduced electrons were transferred from AgHPMo₁₂ to metallic Ag, and combined with the Ag plasmonic holes. The Ag plasmonic electrons were trapped by O₂ to form ·O₂^-, or directly reduced Cr₂O₇^2- to Cr³⁺. Meanwhile, the ·O₂^- species and the photogenerated holes of AgHPMo₁₂ were used to oxidize MO or i-PrOH; thus, they showed highly efficient and recyclable photocatalytic performance for removing the organic and inorganic pollutants.