Chen Menglei, Li Ke, Luo Yuanyuan, Shi Jianping, Weng Chaocang, Gao Lei, Duan Guotao
College of Physics and Electronic Technology, Anhui Normal University, Wuhu, 241000, Anhui, P. R. China.
Phys Chem Chem Phys. 2020 Mar 7;22(9):5145-5153. doi: 10.1039/c9cp05930j. Epub 2020 Feb 19.
The low enhancement factor of semiconductor SERS substrates is a major obstacle for their practical application. Therefore, there is a need to explore the facile synthesis of new SERS substrates and reveal the SERS enhancement mechanism. Here, we develop a simple, facile and low-cost two-step method to synthesize copper sulfide based nanostructures with different CuS contents. The as-synthesized sample is composed of nanosheets with the CuS phase structure. With the increase of the annealing temperature to 300 °C, the CuS content gradually decreases and disappears, and the content of CuS and CuSO appears and gradually increases. At the annealing temperature of 350 °C, only CuSO exists. Compared with pure CuS or pure CuSO, the detection limit of R6G molecules is the lowest for the composite sample with a higher content of CuS, indicating that the introduction of non-stoichiometric CuS can improve the SERS performance and the higher content of CuS leads to a higher SERS activity. Furthermore, to investigate the SERS mechanism, the energy band structures and energy-level diagrams of different probe molecules over CuS, CuS and CuS are studied by DFT calculations. Theoretical calculations indicate that the excellent SERS behavior depends on charge transfer resonance. Our work provides a general approach for the construction of excellent metal compound semiconductor SERS active substrates.
半导体表面增强拉曼散射（SERS）基底的低增强因子是其实际应用的主要障碍。因此，有必要探索新型SERS基底的简便合成方法并揭示SERS增强机制。在此，我们开发了一种简单、便捷且低成本的两步法来合成具有不同硫化铜（CuS）含量的硫化铜基纳米结构。所合成的样品由具有CuS相结构的纳米片组成。随着退火温度升高至300°C，CuS含量逐渐降低并消失，而Cu₂S和CuSO的含量出现并逐渐增加。在350°C的退火温度下，仅存在CuSO。与纯CuS或纯Cu₂SO相比，对于具有较高CuS含量的复合样品，罗丹明6G（R6G）分子的检测限最低，这表明引入非化学计量比的CuS可以提高SERS性能，且较高的CuS含量导致更高的SERS活性。此外，为了研究SERS机制，通过密度泛函理论（DFT）计算研究了不同探针分子在CuS、Cu₂S和CuSO上的能带结构和能级图。理论计算表明，优异的SERS行为取决于电荷转移共振。我们的工作为构建优异的金属化合物半导体SERS活性基底提供了一种通用方法。
