Wu Cheng Hao, Weatherup Robert S, Salmeron Miquel B
Department of Chemistry, University of California, Berkeley, CA 94720, USA and Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
Phys Chem Chem Phys. 2015 Nov 11;17(45):30229-39. doi: 10.1039/c5cp04058b.
Electrode/electrolyte interfaces play a vital role in various electrochemical systems, but in situ characterization of such buried interfaces remains a major challenge. Several efforts to develop techniques or to modify existing techniques to study such interfaces are showing great promise to overcome this challenge. Successful examples include electrochemical scanning tunneling microscopy (EC-STM), surface-sensitive vibrational spectroscopies, environmental transmission electron microscopy (E-TEM), and surface X-ray scattering. Other techniques such as X-ray core-level spectroscopies are element-specific and chemical-state-specific, and are being widely applied in materials science research. Herein we showcase four types of newly developed strategies to probe electrode/electrolyte interfaces in situ with X-ray core-level spectroscopies. These include the standing wave approach, the meniscus approach, and two liquid cell approaches based on X-ray photoelectron spectroscopy and soft X-ray absorption spectroscopy. These examples demonstrate that with proper modifications, many ultra-high-vacuum based techniques can be adapted to study buried electrode/electrolyte interfaces and provide interface-sensitive, element- and chemical-state-specific information, such as solute distribution, hydrogen-bonding network, and molecular reorientation. At present, each method has its own specific limitations, but all of them enable in situ and operando characterization of electrode/electrolyte interfaces that can provide important insights into a variety of electrochemical systems.
电极/电解质界面在各种电化学系统中起着至关重要的作用，但对这种埋藏界面进行原位表征仍然是一项重大挑战。为研究此类界面而开发技术或改进现有技术的多项努力显示出克服这一挑战的巨大潜力。成功的例子包括电化学扫描隧道显微镜（EC-STM）、表面敏感振动光谱、环境透射电子显微镜（E-TEM）和表面X射线散射。其他技术，如X射线芯能级光谱，具有元素特异性和化学态特异性，正在材料科学研究中得到广泛应用。在此，我们展示了四种利用X射线芯能级光谱原位探测电极/电解质界面的新开发策略。这些策略包括驻波法、弯月面法以及基于X射线光电子能谱和软X射线吸收光谱的两种液体池法。这些例子表明，通过适当的改进，许多基于超高真空的技术可用于研究埋藏的电极/电解质界面，并提供界面敏感、元素和化学态特异性信息，如溶质分布、氢键网络和分子重排。目前，每种方法都有其特定的局限性，但所有这些方法都能够对电极/电解质界面进行原位和实时表征，从而为各种电化学系统提供重要的见解。
