Ag/NH2-MIL-125(Ti)的构建及可见光还原水中Cr(Ⅵ)

开发高效、稳定的复合光催化材料是当前环境领域的迫切需求。 本文采用溶剂热协同紫外光还原法成功制备了复合光催化材料Ag/NH₂-MIL-125(Ti),并通过X射线衍射(XRD)、扫描电子显微镜(SEM)、能谱(EDS)、紫外-可见漫反射光谱(UV-Vis DRS)及X射线光电子能谱(XPS)等技术手段对其形貌、结构及光学性质进行分析,考察了Ag/NH₂-MIL-125(Ti)可见光(λ≥420 nm)催化还原Cr(Ⅵ)的性能,并优化了催化剂用量、Cr(Ⅵ)浓度、空穴捕捉剂种类及用量等条件。 结果表明,在最佳条件下,Ag/NH₂-MIL-125(Ti)具有良好的吸附及光催化还原Cr(Ⅵ)性能,其吸附及光催化还原率是NH₂-MIL-125(Ti)的3.11倍,Ag/NH₂-MIL-125(Ti)特殊的“芝麻饼”形貌以及Ag⁰与NH₂-MIL-125(Ti)之间形成的异质结有助于增强复合材料的光催化还原Cr(Ⅵ)的性能。 同时,通过条件实验,提出了光催化还原过程中主要的活性物种以及Cr(Ⅵ) 的还原机理。 本研究将为金属有机骨架(MOFs)复合材料在可见光催化环境修复领域的应用提供理论依据和实验参考。

Construction of Ag/NH2-MIL-125(Ti) Catalyst for Photo-Driven Reduction of Aqueous Cr(Ⅵ) Pollutant

The development of efficient and stable photocatalysts is highly desired and significantly critical for the current environmental field. In this paper, a novel Ag/NH₂-MIL-125(Ti) was successfully prepared by solvothermal coupled with simple ultraviolet(UV) reduction method. The morphology, structure and optical properties of as-prepared samples were characterized by X-ray diffraction(XRD), scanning electron microscopy(SEM), energy dispersive spectroscopy(EDS), UV-Vis diffuse reflectance spectra(DRS) and X-ray photoelectron spectroscopy(XPS). The photo-reduction performance of obtained catalysts were tested on Cr(Ⅵ) removal in various conditions. Under visible light irradiation(λ≥420 nm), the catalysts dosage, heavy metal concentration, pH and hole scavenger were fully investigated to optimize the best Cr(Ⅵ) reduction parameters. The results indicate that Ag/NH₂-MIL-125(Ti) exhibits excellent adsorption and photo-reduction activities on Cr(Ⅵ), which is 3.11 times higher than that of NH₂-MIL-125(Ti). This special “sesame cakes” and heterojunction formation of Ag/NH₂-MIL-125(Ti) are attributed to enhancing Cr(Ⅵ) catalytic reduction performance. Meanwhile, through the control experiments, the main active species during the photo-reduction route were suggested and the mechanism of the Cr(Ⅵ) reduction was proposed. This study will provide theoretical and experimental guidance for the application of novel metal-organic framework(MOF) composites in the field of environmental remediation.