Chromium

Zero-Valent Reaction:

Synthesis Setup:

Chemicals:

Bis(benzene) chromium(0), acetone

Procedure:

Chromium is intercalated by decomposition of chromium(0) coordination compounds. Because these compounds are so sensitive to air, it is necessary to use a Schlenk line or alternative air-free setup. If a Schlenk line isn’t available, setup the reaction as according to the setup above and at the top of the reflux column, add the adapter shown below. Nitrogen or argon gas should feed through one end of the glassware tube with the other left open or sent to a bubbler (put the tube in mineral oil and make sure bubbles come out at a fairly slow rate). Before beginning, place the 2D material in the round-bottom flask, run nitrogen into the column and flask for ~ 30 mins. Alternatively, if on a Schlenk line, place the 2D materials or substrate in the round bottom flask, evacuate, and flush with N₂ or argon gas.

Prepare two stock solutions in a glovebox. Stock solution 1 should have 5mL of acetone in a septa vial. Stock solution 2 should contain 5~10 mM of bis(benzene) chromium(0). For this stock solution, add about 0.01 g of bis(benzene) chromium(0) to 5mL of anhydrous acetone in a septa capped vial. Inject in 5mL of air-free acetone (kept in a glovebox and completely free from air) to the flask and heat to reflux (48-53°C). The air free acetone can be placed in a septa capped vial and injected with syringe that has been flushed with nitrogen three times from the primary flask to prevent any air getting in. Dropwise, inject the second solution to the flask over the course of 2~3 hours. After injection, wait an additional thirty minutes under reflux. Finally, remove substrates or 2D materials from the solution and rinse with acetone in air.

Adapter to bring in nitrogen (Chemglass AF-0509-B) when vacuum line is unavailable.

How much can be intercalated into Bi₂Se₃ nanoribbons:

C₁₂H₁₂Cr	acetone	time	~ intercalated in Bi₂Se₃
0.01 g	Total = 10 mLs	3.5 hours	6 atm % ± 2%

Relevant Publications:

M. Wang, D. Williams, G. Lahti, S. Teshima, D. Dominguez-Aguilar, K. J. Koski, Chemical intercalation of heavy metal, semimetal, and semiconductor atoms into 2D layered chalcogenides. 2D Materials, 5, 045005 (2018)

Supported by NSF DMR-1658019