紫外光辐照法制备金纳米盘及其反应机理

Preparation of Gold Nanoplates by UV Irradiation and the Reaction Mechanisms

用紫外光辐照氯金酸、聚乙烯吡咯烷酮(PVP)和纳米金种子的混合溶液,在室温下用30min制备出尺度小于100nm的截角三角形或六边形金纳米盘.X射线能谱和衍射分析表明粒子是以{111}面为盘状面的高纯面心立方金单晶,红外透射光谱表明金粒子与PVP之间存在作用.产物的可见吸收光谱表现出纳米盘的各向异性表面等离子体共振吸收峰.不同实验条件下产物的吸收光谱分析表明:PVP起还原剂和包覆剂的作用;高强度紫外光加速了反应进行;种子对反应具有催化作用;种子的加入量有最佳值,在该值下纳米盘平均尺度最大(达80nm),吸收谱上的面内偶极共振峰位于950nm处;种子的加入量超过该值时,纳米盘尺度变小,面内偶极共振峰发生蓝移.

Gold nanoplates of truncated triangular or hexagonal shape within 100 nm were prepared by UV irradiation of solution containing HAuC14, poly（vinylpyrrolidone） （PVP） and gold nanoseeds at room temperature within 30 min. Energy-dispersive X-ray spectra, electron diffraction and X-ray diffraction analyses revealed that the nanoplates were highly pure face-centered cubic gold single crystals with { 111 } planes as their basal planes. Infrared transmittance spectra analysis suggested there existed interaction between PVP and gold. The nanoplates showed two surface plasmon resonance （SPR） absorption bands in UV-Vis absorption spectra due to their anisotropic structure. The absorption spectra of products under various experimental conditions indicated that PVP reacted as both reductant and capping agent, high-intensity UV irradiation accelerated the reaction, and the gold seeds imposed catalysis effect on the reaction. The adding amount of seeds held an optimum value at which the average size of the nanoplates reached top as large as 80 nm together with their in-plane dipolar SPR absorption band locating at 950 nm. The size of the nanoplates decreased and the in-plane dipolar band blue-shifted when the adding amount of seeds exceeded that value.