Chlorination of 2D Silicon Revealed by NMR

DFT model and NMR spectrum
(Top) DFT optimized structural model of 2D silicon nanosheets with Si atoms terminated by H, Cl and OH. This structural model is consistent with results from 1H, 29Si, and 35Cl solid-state NMR experiments. (Lower) 1H-detected 35Cl solid-state NMR spectrum. 
Scientific Achievement

Solid-state nuclear magnetic resonance (NMR) spectroscopy methods to detect chlorine atoms were developed and showed that 20% of the silicon atoms in 2D silicon nanosheets are chlorine terminated. 

Significance and Impact

The presence of Cl atoms and OH groups explains the direct band gap of these materials. DFT calculations show that Cl and OH termination can be used to tune the optical and electronic properties of 2D silicon. 

Research Details
  • 2D silicon nanosheets were prepared by topotactic deintercalation of CaSi2 in aqueous hydrochloric acid.
  • 1H{35Cl} NMR experiments show that Cl is homogeneously distributed and covalently bonded to Si atoms. 
  • Hydroxyl groups were also found on the 2D silicon sheets.

Rick W. Dorn, Bradley J. Ryan, Sujeewa N.S. Lamahewage, Mark V. Dodson, Jeremy B. Essner, Rana Biswas, Matthew G. Panthani, and Aaron J. Rossini, Chemistry of Materials 2023, 35, DOI:10.1021/acs.chemmater.2c02980.