Tang Xiao, Fan Xingce, Yao Lei, Li Guoqun, Li Mingze, Zhao Xing, Hao Qi, Qiu Teng
School of Physics, Southeast University, Nanjing 211189, China.
J Phys Chem Lett. 2022 Aug 25;13(33):7816-7823. doi: 10.1021/acs.jpclett.2c02119. Epub 2022 Aug 17.
The plasmonic metal/semiconductor heterojunction provides a unique paradigm for manipulating light to improve the efficiency of plasmonic materials. Previous studies suggest that the improvement originates from the enhanced carrier exchanges between the plasmonic component of the heterojunction and molecules. This viewpoint, known as the chemical mechanism, is reasonable but insufficient, because the construction of the heterojunction will lead to a charge redistribution in the plasmonic component and cause changes in its physical characteristics. Herein, we will try to clarify that these changes are decisive factors in specific applications by investigating the surface-enhanced Raman scattering (SERS) behavior of a typical Ag/TiO heterojunction. We observed significant changes in SERS spectra by modulating the band alignment of the heterojunction in a loop. Identical trends in SERS spectra were observed despite the fact that the charge transfer from the heterojunction to molecules was blocked, suggesting that the major SERS enhancement originates from electromagnetic mechanisms rather than chemical ones.
等离子体金属/半导体异质结为操控光以提高等离子体材料的效率提供了一种独特的范例。先前的研究表明，这种提高源于异质结的等离子体组分与分子之间增强的载流子交换。这种观点，即化学机制，是合理的但并不充分，因为异质结的构建会导致等离子体组分中的电荷重新分布，并引起其物理特性的变化。在此，我们将通过研究典型的Ag/TiO异质结的表面增强拉曼散射（SERS）行为，试图阐明这些变化在特定应用中是决定性因素。我们通过在一个回路中调制异质结的能带排列，观察到SERS光谱发生了显著变化。尽管异质结向分子的电荷转移被阻断，但仍观察到SERS光谱呈现相同的趋势，这表明主要的SERS增强源于电磁机制而非化学机制。
