In situ probing electrified interfacial water structures at atomically flat surfaces

• Published in: Nature materials Vol. 18; no. 7; pp. 697 - 701
• Main Authors: Li, Chao-Yu, Le, Jia-Bo, Wang, Yao-Hui, Chen, Shu, Yang, Zhi-Lin, Li, Jian-Feng, Cheng, Jun, Tian, Zhong-Qun
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.07.2019; Nature Publishing Group
• Subjects: 639/638/161; 639/638/542/969; 639/638/77/886; Atomic structure; Bias; Biomaterials; Chemistry and Materials Science; Condensed Matter Physics; Crystal structure; Electrochemical analysis; Electrochemistry; Electrodes; Flat surfaces; Hydrogen bonding; Hydrogen bonds; Letter; Materials Science; Molecular dynamics; Nanotechnology; Optical and Electronic Materials; Organic chemistry; Raman spectroscopy; Single crystals; Water chemistry
• ISSN: 1476-1122; 1476-4660
• DOI: 10.1038/s41563-019-0356-x

Solid/liquid interfaces are ubiquitous in nature and knowledge of their atomic-level structure is essential in elucidating many phenomena in chemistry, physics, materials science and Earth science 1 . In electrochemistry, in particular, the detailed structure of interfacial water, such as the orientation and hydrogen-bonding network in electric double layers under bias potentials, has a significant impact on the electrochemical performances of electrode materials 2 – 4 . To elucidate the structures of electric double layers at electrochemical interfaces, we combine in situ Raman spectroscopy and ab initio molecular dynamics and distinguish two structural transitions of interfacial water at electrified Au single-crystal electrode surfaces. Towards negative potentials, the interfacial water molecules evolve from structurally ‘parallel’ to ‘one-H-down’ and then to ‘two-H-down’. Concurrently, the number of hydrogen bonds in the interfacial water also undergoes two transitions. Our findings shed light on the fundamental understanding of electric double layers and electrochemical processes at the interfaces. Interfacial water structures in electric double layers under bias potentials can impact the electrochemical performance of electrodes. Two structural transitions of interfacial water at electrified Au single-crystal electrode surfaces have now been identified.