Wang Tzyy-Jiann, Chang Hsuan-Wei, Chen Ji-Sheng, Chiang Hai-Pang
Institute of Electro-Optical Engineering, National Taipei University of Technology, Taipei, 10608, Taiwan.
Institute of Optoelectronic Sciences, National Taiwan Ocean University, Keelung, 20224, Taiwan.
Sci Rep. 2019 Jul 29;9(1):10962. doi: 10.1038/s41598-019-47523-8.
Nanotips made of metal and semiconductor have been widely utilized in versatile applications to strengthen the electric field through lightning rod effect and localized surface plasmon resonance (LSPR) effect. Here, we present the utilization of ferroelectric nanotips to assist photoreduction of silver nanostructures for surface enhanced Raman scattering (SERS). Ferroelectric nanotips with spontaneous polarization posses the unique feature of producing the permanent electrostatic field without requiring external excitation, which differs from the present nanotips requiring electrical and optical excitation. The enhanced electrostatic field promotes the formation of silver nanoparticles by reducing the effect of Stern layer and accelerating the movement of photoelectrons and silver ions to the template surface. Experimental results show that sharp ferroelectric nanotips facilitate the formation of large-diameter nanoparticles with strong LSPR action. Compared to the conventional ferroelectric templates, the SERS substrates using nanotip-equipped ferroelectric templates produce 5.51 times larger Raman intensity, which can be further increased by >10.76 times by increasing the reaction time. The proposed SERS substrate owns the limit of detection <10 M and the enhancement factor of 2.3 × 10. The presented ferroelectric nanotips with permanent electrostatic field would open promising applications in the versatile areas, such as nanomaterial fabrication and optoelectronic devices.
由金属和半导体制成的纳米尖端已被广泛应用于多种领域，通过避雷针效应和局域表面等离子体共振（LSPR）效应来增强电场。在此，我们展示了利用铁电纳米尖端辅助银纳米结构的光还原以用于表面增强拉曼散射（SERS）。具有自发极化的铁电纳米尖端具有无需外部激发就能产生永久静电场的独特特性，这与目前需要电激发和光激发的纳米尖端不同。增强的静电场通过降低斯特恩层的影响并加速光电子和银离子向模板表面的移动，促进了银纳米颗粒的形成。实验结果表明，尖锐的铁电纳米尖端有助于形成具有强LSPR作用的大直径纳米颗粒。与传统的铁电模板相比，使用配备纳米尖端的铁电模板的SERS基底产生的拉曼强度大5.51倍，通过增加反应时间，拉曼强度可进一步提高>10.76倍。所提出的SERS基底的检测限<10 M，增强因子为2.3 × 10。所展示的具有永久静电场的铁电纳米尖端将在纳米材料制造和光电器件等多种领域开启有前景的应用。
