Bao Yi-Fan, Cao Mao-Feng, Wu Si-Si, Huang Teng-Xiang, Zeng Zhi-Cong, Li Mao-Hua, Wang Xiang, Ren Bin
State Key Laboratory of Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China.
Anal Chem. 2020 Sep 15;92(18):12548-12555. doi: 10.1021/acs.analchem.0c02466. Epub 2020 Sep 2.
Electrochemical tip-enhanced Raman spectroscopy (EC-TERS) is a powerful technique for the in situ study of the physiochemical properties of the electrochemical solid/liquid interface at the nanoscale and molecular level. To further broaden the potential window of EC-TERS while extending its application to opaque samples, here, we develop a top-illumination atomic force microscopy (AFM) based EC-TERStechnique by using a water-immersion objective of a high numerical aperture to introduce the excitation laser and collect the signal. This technique not only extends the application of EC-TERS but also has a high detection sensitivity and experimental efficiency. We coat a SiO protection layer over the AFM-TERS tip to improve both the mechanical and chemical stability of the tip in a liquid TERS experiment. We investigate the influence of liquid on the tip-sample distance to obtain the highest TERS enhancement. We further evaluate the reliability of the as-developed EC-AFM-TERS technique by studying the electrochemical redox reaction of polyaniline. The top-illumination EC-AFM-TERS is promising for broadening the application of EC-TERS to more practical systems, including energy storage and (photo)electrocatalysis.
电化学针尖增强拉曼光谱（EC-TERS）是一种强大的技术，可用于在纳米尺度和分子水平上原位研究电化学固/液界面的物理化学性质。为了进一步拓宽EC-TERS的电位窗口，并将其应用扩展到不透明样品，在此，我们通过使用高数值孔径的水浸物镜引入激发激光并收集信号，开发了一种基于顶照式原子力显微镜（AFM）的EC-TERS技术。该技术不仅扩展了EC-TERS的应用范围，而且具有高检测灵敏度和实验效率。我们在AFM-TERS针尖上涂覆一层SiO保护层，以提高针尖在液体TERS实验中的机械稳定性和化学稳定性。我们研究了液体对针尖-样品距离的影响，以获得最高的TERS增强效果。我们通过研究聚苯胺的电化学氧化还原反应，进一步评估了所开发的EC-AFM-TERS技术的可靠性。顶照式EC-AFM-TERS有望将EC-TERS的应用扩展到更实际的系统，包括能量存储和（光）电催化。
