Salt-assisted phase transformation of transition metal dichalcogenides
AssigneeCity University of Hong Kong
InventorsHua Zhang, Zhuangchai Lai
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Abstract
A one-step salt-assisted general synthetic methodology for the controlled phase transformation of various types of 2H-phase transition metal dichalcogenides (2H-TMDs), yielding large-scale metastable 1T′-phase transition metal dichalcogenides (1T′-TMDs), including WS2, WSe2, MoS2, and MoSe2 is described. By tuning the reaction conditions, alloyed 1T′-TMDs such as WS2xSe2(1−x) and MoS2xSe2(1−x) are also obtained. Commercially-available metal salts such as K2C2O4·H2O, Na2C2O4, K2CO3, Na2CO3, Cs2CO3, Rb2CO3, KHCO3, and NaHCO3, are demonstrated to be effective for the controlled phase transformation at elevated temperatures in a reducing atmosphere. The technique may be extended to the phase engineering of other materials with various polymorphs.
Claims10
A method for phase transformation of transition metal dichalcogenides from a stable phase to a metastable phase, comprising:
- mixing a phase 2H or 3R transition metal dichalcogenide with an alkali metal salt;
- heating the mixed 2H or 3R transition metal dichalcogenide with alkali metal salt at a temperature of 700-1000° C. in a reducing atmosphere to form a reaction product;
- and
- recovering a 1T or 1T′ metastable phase of the transition metal dichalcogenide from the reaction product.
Dependencies are inferred from the claim text.