Wang Yawen

Low temperature preparation of flower-like BiOCl film and its photocatalytic activity

The BiOCl thin film with flower-like sphere structure was prepared at a low temperature by the alcoholysis-coating method using BiCl3 as precursor. The obtained thin film was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), electronic energy spectrum (EDS) and ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS). And the results showed that the obtained BiOCl film without calcination was composed of flower-like sphere structure with tetragonal phase and had a good absorption for ultraviolet. The photocatalytic activity of BiOCl thin film was also evaluated by the degradation of methyl orange in water under UV light irradiation. The degradation experimental results confirmed that the film prepared at low temperature possessed a high photocatalytic activity and could achieve 97% degradation to 10 mg/L methyl orange solution after 150 min UV light irradiation. The stability of the obtained BiOCl thin film was also good and its photocatalytic activity still remained an above 94% removal of methyl orange after being used four times. In addition, a possible formation mechanism of BiOCl thin film was also inferred and the results suggested that the ethylene glycol solvent may contribute to the forming flower-like sphere structure.

Synthesis, Regeneration and Photocatalytic Activity under Visible-Light Irradiation of Ag/Ag 3 PO 4 /g-C 3 N 4 Hybrid Photocatalysts

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(λ>420nm)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.更多还原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 Xray diffraction (XRD), fieldemission scanning electron microscopy (FESEM), ultravioletvisible (UVVis) absorption spectroscopy, and Xray 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/gC3N4 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 gC3N4. 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 Ag. 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. 729 Acta Phys. -Chim. Sin. 2014 Vol.30