Brief Introduction

We developed a series of novel chemistry methods to controllably insert and remove the zero-valent metals/alloy in the van der Waals gap of 2D layered hosts. The library of zero-valent metal includes Cr, Mn, Fe, Co, Ni, Cu, Sb, Ru ... , as highlighted in the above periodic table of elements. Corresponding reversible deintercalation chemistries in both oxide and chalcogenide system were also developed.

More details can be found in:

• M. Wang, D. Williams, G. Lathi, S. Teshima, D. Aguilar, R. Perry, K. J. Koski*. Chemical Intercalation of Heavy Metal, Semimetal, and Semiconductor Atoms into 2D Layered Chalcogenides. 2D Mater. 5, 045005 (2018).
• M. Wang, I. Al-Dhahir, J. Appiah, K. J. Koski*. Deintercalation of Zero-Valent Metals from Two-Dimensional Layered Chalcogenides. Chem. Mater. 29, 1650-1655 (2017).
• K. P. Chen, F. R. Chung, M. Wang, K. J. Koski*. Dual Element Intercalation into 2D Layered Bi2Se3 Nanoribbons. J. Am. Chem. Soc. 137, 5431–5437 (2015).

Intercalation of zero-valent metals (Cu, Co, Sn, Fe, etc.) in the layered materials brings in new structural motifs along with phase transitions. For example, stripe phase, hexagonal domain, superlattice, and charge density wave (CDW) could coexist in the Cu⁰ intercalated Bi₂Se₃ system. The ordering of the intercalants as a function of temperature and intercalant concentration could be investigated via analyzing SAED patterns obtained from in situ TEM. Examples of such phase transitions can be found in Bi2Se3 (see above) and MoO3 systems.

More details can be found in:

• M. Wang, K. J. Koski. Polytypic Phase Transitions in Metal Intercalated Bi2Se3. J. Phys.: Condens. Matter. 28, 494002 (2016).
• M. Wang, K. J. Koski. Reversible Chemochromic MoO3 Nanoribbons through Zero-valent Metal Intercalation. ACS Nano. 9, 3226-3233 (2015).
• B. W. Reed, F. R. Chung, M. Wang, T. Lagrange, K. J. Koski. Disorder-Order transition in 2D copper-intercalated MoO3 using dynamic transmission electron microscopy. 2D Mater. 1, 035001 (2014).

Intercalation of zero-valent metals and phase transition of the intercalants introduce lots of interesting properties to the 2D layered host. It can engineer the band gap of 2D host as well as change its color, transparency. Reversible intercalation and deintercalation open up a new way to controllably change electronic and optical properties of layered host. Examples could be found in Si2Te3 (above left) and MoO3 (above right) systems.

More details can be found in:

• M. Wang, D. Williams, G. Lathi, K. J. Koski*. Chemically Tunable Full Spectrum Optical Properties of 2D Silicon Telluride Nanoplates. ACS Nano 12, 6163-6169 (2018).
• M. Wang, K. J. Koski*. Reversible Chemochromic MoO3 Nanoribbons through Zero-valent Metal Intercalation. ACS Nano 9, 3226-3233 (2015).