Ag/Ag_3PO_4/g-C_3N_4复合光催化剂的合成与再生及其可见光下的光催化性能(英文)

研究了用离子交换沉淀法制备的Ag/Ag3PO4/g-C3N4的可见光光催化性能及再生方法.通过X射线衍射(XRD)、场发射扫描电子显微镜(FESEM)、紫外-可见(UV-Vis)吸收光谱及X射线光电子能谱(XPS)对其进行了结构特性分析.XRD结果显示再生后催化剂的结构未发生改变.FESEM及UV-Vis分析结果说明催化剂由Ag3PO4与g-C3N4复合而成.XPS分析结果表明催化剂表面出现少量的银单质.利用可见光(λ420nm)照射下的苯酚降解实验评价了样品的光催化活性,并通过活性物种及能带结构的分析对催化剂的光催化机理进行了推测.研究表明,Ag/Ag3PO4/g-C3N4的光催化活性明显高于纯Ag3PO4及纯g-C3N4,主要原因归结为单质银、Ag3PO4及g-C3N4的协同效应.经过氧化氢和磷酸氢铵钠(NaNH4HPO4)的再生可完全恢复催化剂的活性,这表明该绿色环保的再生方法可实现Ag/Ag3PO4/g-C3N4催化剂在环境中的实际应用.

Synthesis,Regeneration and Photocatalytic Activity under Visible-Light Irradiation of Ag/Ag3PO4/g-C3N4 Hybrid Photocatalysts

Ag/Ag₃PO₄/g-C₃N₄ (g denotes graphitic) was synthesized via an anion-exchange precipitation method, and its photocatalytic activity under visible light and regeneration with H₂O₂ and NaNH₄HPO₄ were investigated. The structural characteristics were analyzed using X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), ultraviolet-visible (UV-Vis) absorption spectroscopy, and X-ray photoelectron spectroscopy (XPS). The XRD results showed that the structure of the regenerated catalyst was unchanged. The FESEM and UV-Vis absorption spectroscopy results showed that the Ag/Ag₃PO₄/g-C₃N₄ catalyst was composed of Ag₃PO₄ and g-C₃N₄. XPS showed that a small amount of Ag particles were present on the catalyst surface. The photocatalytic activity was evaluated using phenol degradation under visible light (λ>420 nm) and the photocatalytic mechanism was discussed based on the active species during the photocatalytic process and the band structure. Experimental studies showed that the photocatalytic activity of the as-prepared Ag/Ag₃PO₄/g-C₃N₄ was higher than those of pure Ag₃PO₄ and g-C₃N₄. The high photocatalytic performance of the Ag/Ag₃PO₄/g-C₃N₄ composite can be attributed to the synergistic effect of Ag₃PO₄, g-C₃N₄, and a small amount of Ag⁰. Regeneration using H₂O₂ and NaNH₄HPO₄? 4H₂O fully restored the photoactivity of the catalyst, showing that this green regeneration method could make Ag/Ag₃PO₄/g-C₃N₄ an environmentally friendly catalyst for practical applications.