Advances in Atomic Force Microscopy: Weakly Perturbative Imaging of the Interfacial Water.

Duanyun Cao,Jinbo Peng,Xinzheng Li,Enge Wang,Yizhi Song,Ying Jiang,Limei Xu,Jing Guo,Runze Ma,Ji Chen

doi:10.3389/fchem.2019.00626

Abstract

The structure and dynamics of interfacial water, determined by the water-interface interactions, are important for a wide range of applied fields and natural processes, such as water diffusion (Kim et al., 2013), electrochemistry (Markovic, 2013), heterogeneous catalysis (Over et al., 2000), and lubrication (Zilibotti et al., 2013). The precise understanding of water-interface interactions largely relies on the development of atomic-scale experimental techniques (Guo et al., 2014) and computational methods (Hapala et al., 2014b). Scanning probe microscopy has been extensively applied to probe interfacial water in many interdisciplinary fields (Ichii et al., 2012; Shiotari and Sugimoto, 2017; Peng et al., 2018a). In this perspective, we review the recent progress in the noncontact atomic force microscopy (nc-AFM) imaging and AFM simulation techniques and discuss how the newly developed techniques are applied to study the properties of interfacial water. The nc-AFM with the quadrupole-like CO-terminated tip can achieve ultrahigh-resolution imaging of the interfacial water on different surfaces, trace the reconstruction of H-bonding network and determine the intrinsic structures of the weakly bonded water clusters and even their metastable states. In the end, we present an outlook on the directions of future AFM studies of interfacial water as well as the challenges faced by this field.

Highlights

Water-interface interactions are of vital importance in both fundamental science (Xu et al, 2010) and application fields (Markovic, 2013)
In the observation of H2O-OH mixed network, they found that H atoms are invisible in the atomic force microscopy (AFM) images, the O-O distance correlated highly with the strength of H-bonds can be sensitively detected, H-bonds can be detected by AFM. They demonstrated that AFM imaging can trace the reconstruction of H-bonding network in real time, it can be rearranged readily and is more flexible than the covalently bonded organic molecules. These findings further demonstrated that AFM is practical to characterize atomic structures of weakly bonded molecular structures, and its application to water systems leads to major breakthroughs in the study of watersolid interfaces
We discuss the recent advances in AFM and how the newly developed techniques are applied to the study of interfacial water

Summary

Introduction

Water-interface interactions are of vital importance in both fundamental science (Xu et al, 2010) and application fields (Markovic, 2013). The intricate relation between the AFM signal and the measured structure, for instance sharp ridges observed by AFM between atoms without the real chemical bond, signify that the mechanism of high-resolution imaging is worth investigating.

Results

Conclusion