聚乙烯吡咯烷酮碱性水溶液中金纳米花的简易合成

Facile Synthesis of Gold Nanoflowers in a Polyvinyl Pyrrolidone Alkaline Aqueous Solution

以聚乙烯吡咯烷酮(PVP)兼作保护剂和还原剂在碱性水溶液中直接还原HAuCl4制备出了60-80nm的三维(3D)金纳米花.产物的透射电子显微镜(TEM)和扫描电子显微镜(SEM)图像显示,金纳米花表面布满10-15nm左右的纳米触角,X射线衍射(XRD)表征揭示产物为金的面心立方晶体,选区电子衍射(SAED)花样说明金纳米花为多晶结构.金纳米花的生长经历了三个关键步骤,即初级纳米晶聚集成多脚状纳米粒子,随后在合适的PVP/HAuCl4浓度比及NaOH浓度下,多脚状纳米粒子进一步聚集形成疏松的花状粒子,最终经过Ostwald熟化形成致密的花状产物.一定HAuCl4浓度下PVP/HAuCl4浓度比和NaOH浓度对产物的形貌影响显著,因此通过同时调控合适的PVP/HAuCl4浓度比和NaOH浓度,就能得到适应各种应用需求的尺度可控和纳米触角形貌可控的金纳米花.

Three-dimensional （3D） gold nanoflowers of 60-80 nm in diameter were successfully synthesized using polyvinyl pyrrolidone （PVP） as both a protecting agent and a reducing agent in alkaline aqueous solutions. Transmission electron microscopy （TEM） and scanning electron microscopy （SEM） images revealed that many antennae of 10-15 nm existed on their surfaces. X-ray diffraction （XRD） pattern suggested face-centered cubic （fcc） structures for these gold nanoflowers. The selected area electron diffraction （SAED） pattern of a single gold nanoflower indicated polycrystal characteristics. We found that there were three key stages in the growth of the gold nanoflowers： primary nanocrystals agglomerated to form multipod-like nanoparticles, and then the multipod-like nanoparticles aggregated into loose flower-like nanoparticles that ultimately grew into compact gold nanoflowers through Ostwald ripening. During the synthesis of gold nanoflowers, the molar ratios of PVP/HAuCl4 at fixed HAuCl4 and NaOH concentrations mostly influenced the morphologies of the final products. Therefore, a proper molar ratio of PVP/HAuCl4 and a suitable NaOH concentration were essential for the synthesis of typical gold nanoflowers with controlled sizes and antenna architectures.