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-TiO₂ composite nanofibers loaded with Ag nanoparticles (NPs), labeled as PMo₁₂/TiO₂/Ag-X (PMo₁₂ = [PMo₁₂O₄₀]³⁻; X represents the weight percent (%) of Ag in PMo₁₂/TiO₂/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 PMo₁₂/TiO₂ composite fibers is about 130 ± 30 nm, and the average size of Ag NPs is about 15 ± 5 nm. Photocatalytic experiments confirm that PMo₁₂/TiO₂/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, PMo₁₂/TiO₂/Ag-5.41 exhibits the highest photocatalytic activity. The photocatalytic mechanism reveals that both Ag and PMo₁₂ 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 TiO₂, 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.

中文翻译：

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在可见光下具有增强的光催化性能的多金属氧酸盐/ TiO ₂ / Ag复合纳米纤维

探索用于废水处理的高效稳定的可见光驱动光催化剂已被认为是目前环境修复中最具挑战性的主题之一。在本文中，我们报告了一种新型的载有Ag纳米颗粒（NPs）的多金属氧酸盐-TiO ₂复合纳米纤维，标记为PMo ₁₂ / TiO ₂ / Ag-X（PMo ₁₂  = [PMo ₁₂ O ₄₀ ] ³⁻； X代表PMo ₁₂ / TiO ₂ / Ag样品中Ag的重量百分比（％）； X分别为3.98、5.41、6.83和7.19）。SEM和TEM图像显示PMo ₁₂ / TiO ₂的平均直径复合纤维的厚度约为130±30 nm，Ag NP的平均尺寸约为15±5 nm。光催化实验证实PMo ₁₂ / TiO ₂ / Ag催化剂在可见光（λ> 420 nm）下对甲基橙（MO）的光降解和Cr（VI）的光还原表现出高效且持久的活性。在这些复合系列中，PMo ₁₂ / TiO ₂ /Ag-5.41表现出最高的光催化活性。光催化机理表明，Ag和PMo ₁₂均可在可见光照射下被激发，从而大大提高了复合材料的可见光吸收率。此外，引入POM物质不仅可以提高TiO的光吸收和氧化还原活性_{如图2所示}，由于聚氧阴离子的相对窄的带隙和低的可逆氧化还原电势，还促进了等离子体复合物的光化学稳定性。这种基于POM的等离激元光催化剂在以低成本，高效率和耐用性设计和探索新型光催化材料的持续努力中很重要。