二氧化钛包裹金纳米棒核壳材料的制备及其光解水制氢

利用溶胶凝胶法制备了金纳米棒(GNR)与TiO₂的核壳结构复合材料--GNR@TiO₂,粒径为200 nm左右。 经水热晶化后的材料粒径为300 nm左右,GNR形貌和局域表面等离子共振(LSPR)峰保持稳定,其外边包裹着树枝状的锐钛矿相TiO₂壳层。 采用X射线衍射(XRD)、高分辨透射电子显微镜(HRTEM)、X射线光电子能谱分析(XPS)、紫外可见吸收光谱、光催化制氢性能等技术手段测试表征了样品的结构及性能。 结果表明,晶化后的GNR@TiO₂在可见光范围内制氢速率为31.0 μmol/(g·h),相较与晶化前7.3 μmol/(g·h)得到了明显提升。 最后结合实验结果和时域有限差分(FDTD)分析了催化产氢机理:LSPR促进了可见光吸收,锐钛矿TiO₂对电场的增强促进了光生电子-空穴分离,同时晶化后的TiO₂壳层疏松多介孔,增加了活性位点,有利于传质。

Synthesis of TiO2 Coated Gold Nanorod with Core-Shell Structure and Its Photocatalytic Hydrogen Evolution

TiO₂ coated gold nanorods with core-shell structure(GNR@TiO₂) about 200 nm were synthesized by sol-gel process and hydrothermal method. After hydrothermal crystallization, the particle size of the material expands to 300 nm, while the morphology and the local surface plasmon resonance(LSPR) of GNR have no change. The structure and properties of the samples were characterized by X-ray diffraction(XRD), high resolution transmission electron microscope(HRTEM), X-ray photoelectron spectroscopy(XPS), ultraviolet-visible absorption spectroscopy and photocatalytic hydrogen production. The results show that the hydrogen production rate of crystallized GNR@TiO₂ is 31.0 μmol/(g·h) in the visible light range, which is much higher than that of 7.3 μmol/(g·h) before crystallization. Based on experimental result and finite difference time domain(FDTD) analysis, we proposed a photocatalytic mechanism for efficient hydrogen generation. LSPR promotes the visible light absorption. Anatase TiO₂ enhances the electric field and promotes the photogenerated electron-hole separation. The crystallized TiO₂ shell is porous and multi-mesoporous, which increases the active sites and is conducive to material transfer.