金/氧化亚铜异质球的制备及其可见光催化性能

使用L-半胱氨酸作为连接剂, 利用硼氢化钠原位还原预先吸附在介孔氧化亚铜表面的氯金酸根离子,得到了Au/Cu₂O异质结构. 应用X射线粉末衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)、X射线光电子能谱(XPS)、紫外-可见(UV-Vis)光谱和N₂物理吸附等手段对催化剂进行表征, 并以λ>400 nm的可见光作为光源, 评价了该催化剂光催化降解亚甲基蓝(MB)的活性. 实验结果表明, 直径为4 nm的金颗粒完好地负载在介孔氧化亚铜的表面, 并且介孔氧化亚铜的细微结构与孔径均未发生变化. 研究表明, 以乙醇作为反应溶剂有效抑制了AuCl₄^-与Cu₂O之间的氧化还原反应, 从而有利于氧化亚铜介孔结构的保持及金颗粒的原位还原. 光催化降解亚甲基蓝的结果表明, Au/Cu₂O异质结构的光催化活性比纯氧化亚铜光催化活性有明显提高. 推测其光催化性能提高的主要原因如下: 一方面, 金颗粒良好的导电性有利于氧化亚铜表面电子的快速转移, 实现电子-空穴分离; 另一方面, 金颗粒可能存在的表面等离子共振现象加速了光生电子的产生.

Synthesis and Visible Light Photocatalytic Activities of Au/Cu2O Heterogeneous Nanospheres

Au/Cu₂O heterogeneous spheres (HGS) were prepared by in situ reduction of preadsorbed AuCl₄^- on the surface of Cu₂O mesoporous spheres (MPS) linked by L-cysteine. The resulting products were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV-Vis diffuse reflectance spectroscopy (DRS), and N₂ physical adsorption. The photocatalytic activity of the samples was evaluated by photocatalytic degradation of methylene blue (MB) under visible light (λ>400 nm) irradiation. The experimental results revealed that the Cu₂O MPS kept their mesoporous structure after loading with Au, and small Au nanoparticles (NPs) with a diameter of ~4 nm were identified on the surface of the MPSs. N₂ physical adsorption analysis showed that the pore size distributions of Cu₂O MPSs were unchanged after loading with Au NPs. Using ethanol as a solvent retarded the redox reaction between AuCl₄^- and Cu₂O, avoiding damage to the mesoporous structures. The Au/Cu₂O HGSs exhibited higher visible-light photocatalytic activity for the degradation of methylene blue than the pure Cu₂O MPSs. The enhanced photocatalytic efficiency of the Au/Cu₂O HGSs was attributed to rapid charge transfer from Cu₂O to the loaded Au NPs as well as the surface plasmon resonance of Au NPs.