​ACS NANO Reports the Latest Research from Tianchao Niu and Shuang Li's group


RecentlyProf. Tianchao Niu from Herbert Gleiter Institute of nanoscience and A/Prof. Shuang Li from Nano and Heterogeneous Materials Center, School of Material Science and Engineering, Nanjing University of Science & Technology, co-published a research paper entitled Imaging and Dynamics of Water Hexamer Confined in Nanoporous in the well-known international journal ACS Nano (IF13.7). (Paper Links: https://pubs.acs.org/doi/10.1021/acsnano.9b04835 ), master student Nan Si and doctoral student Tao Shen are the co-first authors.

 

Water is the most widely distributed substance on earth. Understanding of the structure of water and its interaction with other substances at atomic scale is still the focus and also a big challenge of current water science research. Simultaneous achieving molecular-scale observations and maintaining the intrinsic properties of water is extremely harsh for selecting a model system for scanning tunneling microscopy. Blue phosphorene, an allotrope of black phosphorene, is a two-dimensional material with regular hexagonal structure. However, epitaxial growth of blue phosphorene on Au(111) exhibits a honeycomb reconstruction with periodic nanopores. The molecules and atoms can be localized in the nanopores. Employing blue phosphorene with reduced density of states leads to a long excited-state lifetime that allows us to directly image the dynamics of the adsorbate. At the same time, the weak interfacial interactions recover the intrinsic properties of water.

 

We use molecular beam epitaxy to prepare the monolayer blue phosphorene on Au(111) substrate. The controversial atomic structure model of blue phosphorene was revealed by density functional theory. Subsequently, high-resolution scanning tunneling microscopy/spectroscopy combined with first-principles calculations confirmed that water molecules aggregate into hexamers in the nanopores of blue phosphorene. The vibration of inelastic electron-excited water molecules was observed. We found a localized interfacial charge rearrangement between the water hexamer and P atoms underneath that is responsible for the reversible desorption and adsorption of water molecules by changing the sample bias polarity, offering a promising strategy for engineering the electronic properties of blue phosphorene.

 

This work is financially supported by the Natural Science Foundation of Jiangsu Province, the National Natural Science Foundation of China, and the Fundamental Research Funds for Central Universities.