Reversible Semimetal-Semiconductor Transition of Unconventional-Phase WS2 Nanosheets

摘要

Phasetransition with band gap modulation of materials has gainedintensive research attention due to its various applications, includingmemories, neuromorphic computing, and transistors. As a powerful strategyto tune the crystal phase of transition-metal dichalcogenides (TMDs),the phase transition of TMDs provides opportunities to prepare newphases of TMDs for exploring their phase-dependent property, function,and application. However, the previously reported phase transitionof TMDs is mainly irreversible. Here, we report a reversible phasetransition in the semimetallic 1T '-WS2 driven byproton intercalation and deintercalation, resulting in a newly discoveredsemiconducting WS2 with a novel unconventional phase, denotedas the 1T '(d) phase. Impressively, an on/off ratioof >10(6) has been achieved during the phase transitionofWS(2) from the semimetallic 1T ' phase to the semiconducting1T '(d) phase. Our work not only provides a uniqueinsight into the phase transition of TMDs via proton intercalationbut also opens up possibilities to tune their physicochemical propertiesfor various applications.